WDIFF

draft-ietf-aaa-diameter-00.txt --> draft-ietf-aaa-diameter-01.txt

AAA Working Group Pat R. Calhoun
Internet-Draft Sun Microsystems, Inc.
Category: Standards Track Allan C. Rubens
<draft-ietf-aaa-diameter-00.txt>
<draft-ietf-aaa-diameter-01.txt> Tut Systems, Inc.
Haseeb Akhtar
Nortel Networks
Erik Guttman
Sun Microsystems, Inc.
February
March 2001

Diameter Base Protocol

Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at:

http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at:

http://www.ietf.org/shadow.html.

Distribution of this memo is unlimited.

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Abstract

The Diameter base protocol is intended to provide a AAA framework for
Mobile-IP, NASREQ and ROAMOPS. This draft specifies the message
format, transport, error reporting and security services to be used
by all Diameter extensions and MUST be supported by all Diameter
implementations.

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Table of Contents

1.0 Introduction
1.1 Requirements language
1.2 Terminology
2.0 Protocol Overview
2.1 Header Format Transport
2.2 Securing Diameter Messages
2.3 Diameter Server Discovery
2.4 Mandatory Accounting Support
3.0 Diameter Header
3.1 Command Code Definitions
2.3 AVP Format
2.3.1
4.0 Diameter AVPs
4.1 AVP Header
2.3.2
4.2 Optional Header Elements
2.3.3
4.3 AVP Data Formats
2.3.4
4.4 Grouped AVP Values
2.3.4.1
4.4.1 Example AVP with a Grouped Data type
2.3.5
4.5 Diameter Base Protocol AVPs
2.4 Mandatory AVPs
2.4.1 Host-Name
5.0 Message Forwarding
5.1 Origin-FQDN AVP
2.5 State Machine
2.6
5.2 Origin-Realm AVP
5.3 Destination-FQDN AVP
6.0 Capabilities Negotiation
6.1 Device-Reboot-Ind (DRI) Command
2.6.1
6.1.1 Vendor-Id AVP
2.6.2
6.1.2 Firmware-Revision AVP
2.6.3
6.1.3 Extension-Id AVP
2.6.4
6.1.4 Host-IP-Address AVP
2.7 Diameter Server Discovery
3.0 "User" Sessions
3.1
7.0 Transport Failure Detection
7.1 Device-Watchdog-Request
7.2 Device-Watchdog-Answer
7.3 Failover/Failback Procedures
8.0 Peer State Machine
3.2 Session-Id AVP
3.3 Authorization-Lifetime AVP
3.4 Session-Timeout AVP
3.5 User-Name
9.0 Per-Hop Error Signaling
9.1 Device-Status-Ind
9.1.1 Device-Error AVP
3.6 Session Termination
3.6.1 Session-Termination-Ind
3.6.2 Session-Termination-Request
3.6.3 Session-Termination-Answer
4.0 Reliable Transport
5.0
9.1.1.1 Informational Events
9.1.1.2 Redirect Event
9.1.1.3 Transient Failure Events
9.1.1.4 Permanent Failure Events
10.0 End-to-End Error Reporting
5.1 Signaling
10.1 Message-Reject-Ind (MRI) Command
5.1.1
10.1.1 Failed-AVP AVP
5.1.2
10.1.2 Failed-Command-Code
10.2 Result-Code AVP
10.2.1 Informational
10.2.2 Success

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5.2 Result-Code AVP
5.2.1 Informational
5.2.2 Success
5.2.3

10.2.3 Redirect Notification
5.2.4
10.2.4 Transient Failures
5.2.5
10.2.5 Permanent Failures
5.2.6 Hop-by-Hop Failures
5.3
10.3 Error-Message AVP
5.4 Error-Reporting-NAI
10.4 Error-Reporting-FQDN AVP
6.0
11.0 "User" Sessions
11.1 Session State Machine
11.2 Session-Id AVP
11.3 Authorization-Lifetime AVP
11.4 Session-Timeout AVP
11.5 User-Name AVP
11.6 Max-Wait-Time AVP
11.7 Session Termination
11.7.1 Session-Termination-Ind
11.7.2 Session-Termination-Request
11.7.3 Session-Termination-Answer
12.0 Message Routing
6.1
12.1 Realm-Based Message Routing
6.2 Behavior of
12.1.1 Realm-Based Routing Table
12.2 Proxy and Redirect Servers
6.2.1 Server handling of requests
12.2.1 Proxy and Redirect Server handling of requests
6.3
12.3 Redirect Server
6.3.1
12.3.1 Redirect-Host AVP
6.3.2
12.3.2 Redirect-Host-Address AVP
6.3.3
12.3.3 Redirect-Host-Port AVP
6.4
12.4 Proxy Server
6.4.1
12.4.1 Proxying Requests
6.4.2
12.4.2 Proxying Responses
6.4.3
12.4.3 Route-Record AVP
6.4.4
12.4.4 Proxy-State AVP
6.4.5
12.4.5 Proxy-Address AVP
6.4.6
12.4.6 Proxy-Info AVP
6.4.7 Routing-Realm
12.4.7 Destination-Realm AVP
6.5
12.5 Applying Local Policies
6.6
12.6 Hiding Network Topology
6.7
12.7 Loop Detection
6.8 Finding a Target NAS within a Domain
6.8.1 Destination-NAI AVP
7.0
13.0 Diameter Message Security
7.1
13.1 Hop-by-Hop Security
7.1.1
13.1.1 Integrity-Check-Value AVP
7.1.1.1
13.1.1.1 Authentication-Transform-Id AVP
7.1.1.2
13.1.1.2 Digest AVP
7.1.2
13.1.2 Encrypted-Payload AVP
7.1.2.1
13.1.2.1 Encryption-Transform-Id AVP
7.1.2.1.1
13.1.2.1.1 MD5 Payload Hiding
7.1.2.2
13.1.2.2 Plaintext-Data-Length AVP
7.1.2.3
13.1.2.3 Encrypted-Data AVP
7.2
13.2 Nonce AVP
7.3
13.3 Timestamp AVP
7.4

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13.4 Key-Id AVP
8.0
14.0 AVP Table
9.0
15.0 IANA Considerations
9.1
15.1 AVP Attributes
9.2
15.2 Command Code AVP Values
9.3
15.3 Extension Identifier Values

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9.4
15.4 Result-Code AVP Values
9.5
15.5 Integrity-Check-Value AVP Transform Values
9.6
15.6 Encryption-Transform-Id AVP Values
9.7
15.7 Message Header Bits
9.8
15.8 AVP Header Bits
10.0
15.9 DSI-Event AVP Values
16.0 Open Issues
11.0
17.0 Diameter protocol related configurable parameters
12.0
18.0 Security Considerations
13.0
19.0 References
14.0
20.0 Acknowledgements
15.0
21.0 Authors' Addresses
16.0
22.0 Full Copyright Statement
Appendix A. Diameter Service Template

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1.0 Introduction

The Diameter protocol allows peers to exchange a variety of messages.
The base protocol provides the following facilities:

- Delivery of AVPs (attribute value pairs)
- Capabilities negotiation, as required in [20]
- Error notification
- Extensibility, through addition of new commands and AVPs, as
required in [21]

All data delivered by the protocol is in the form of an AVP. Some of
these AVP values are used by the Diameter protocol itself, while
others deliver data associated with particular applications which
employ Diameter. AVPs may be added arbitrarily to Diameter messages,
so long as the required AVPs are included and AVPs which are
explicitly excluded are not included. AVPs are used by base Diameter
protocol to support the following required features:

- Transporting of user authentication information, for the
purposes of enabling the Diameter server to authenticate the
user.
- Transporting of service specific authorization information,
between client and servers, allowing the peers to decide whether
a user's access request should be granted.
- Exchanging resource usage information, which MAY be used for
accounting purposes, capacity planning, etc.
- Proxying and Re-directing of Diameter messages through a server
hierarchy.
- Providing application-level security, through the use of the
Integrity-Check-Value (ICV) and Encrypted-Payload AVPs.

The Diameter base protocol provides the minimum requirements needed
for an AAA transport protocol, as required by NASREQ [21], Mobile IP
[22, 23], and ROAMOPS [20]. The base protocol is not intended to be
used by itself, and must be used with an application-specific
extension, such as Mobile IP [10]. The Diameter protocol was heavily
inspired and builds upon the tradition of the RADIUS [1] protocol.

Any node can initiate a request. In that sense, Diameter is a peer to
peer protocol. In this document, a Diameter client is the device that
normally initiates a request for authentication and/or authorization
of a user. A Diameter server is the device that either forwards the
request to another Diameter server (known as a proxy), or one that
performs the actual authentication and/or authorization of the user
based on some profile. Given that the server MAY send unsolicited
messages to clients, it is possible for the server to initiate such
messages. An example of an unsolicited message would be for a request

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that the client issue an accounting update.

Diameter services require sequenced in-order reliable delivery of
data, with congestion control (receiver windowing). Timely detection
of failed or unresponsive peers is also required, allowing for robust
operation. TCP is insufficient for this second requirement.
Diameter SHOULD be transported over SCTP [26].

1.1 Requirements language

In this document, the key words "MAY", "MUST", "MUST NOT",
"optional", "recommended", "SHOULD", and "SHOULD NOT", are to be
interpreted as described in [13].

1.2 Terminology

Refer to [9] for terminology used in this document.

2.0 Protocol Overview

The base Diameter protocol is never used on its own. It is always
extended for a particular application. Four extensions to Diameter
are defined by companion documents: NASREQ [7], Mobile IP [10],
Accounting Extension [15], Strong Security [11]. These options are
introduced in this document but specified elsewhere. Additional
extensions to Diameter may be defined in the future (see Section
9.3).
15.3).

The base Diameter protocol concerns itself with capabilities
negotiation, and how messages are sent and how peers may eventually
be abandoned. The base protocol also defines certain rules which
apply to all exchanges of messages between Diameter peers. It is
important to note that the base protocol provides optional
application-level security AVPs (Integrity-Check-Value) which MAY be
used in absence of an underlying security protocol (e.g. IP
Security).

Communication between Diameter peers begins with one peer sending a
message to another Diameter peer. The set of AVPs included in the
message is determined by a particular application of or extension to
Diameter. We will refer to this as the Diameter extension. One AVP
that is included to reference a user's session is the Session-Id.

The initial request for authentication and/or authorization of a user
would include the Session-Id. The Session-Id is then used in all

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subsequent messages to identify the user's session (see section 3.0 11.0
for more information). The communicating party may accept the
request, or reject it by returning a response with Result-Code AVP
set to indicate an error occurred. The specific behavior of the
diameter server or client receiving a request depends on the Diameter
extension employed.

Session state (associated with a Session-Id) MUST be freed upon
receipt of the Session-Termination-Request, Session-Termination-
Answer, expiration of authorized service time in the Session-Timeout
AVP, and according to rules established in a particular
extension/application of Diameter.

Exchanges of messages are either request/reply oriented, or in some
special cases, do not require replies. All such messages that do not
require replies have names ending with '-Ind' (short for Indication).

The Diameter base protocol provides the Authorization-Lifetime AVP,
which MAY be used by extensions to specify the duration of a specific
authorized session.

2.1 Header Format Transport

The base Diameter protocol is run over SCTP [26] on port TBD of both TCP [27] and
SCTP [26] transport protocols (for interoperability test purposes we will support
port 1812 will be used until April 2001). Implementations MAY send packets from any source port, but Diameter clients [9] MUST be prepared to receive packets on port TBD. When a request is
received, in order
support TCP, but are warned that future versions of this
specification may mandate SCTP support. Diameter servers MUST support
both TCP and SCTP.

A Diameter node MAY sent packets from any source port, but MUST be
prepared to send receive packets on port TBD. When a reply, request is received,
the source and destination destionation ports in the reply are reversed. Note
that the source and destination addresses used in request and replies
MAY be any of the a peer's valid IP addresses.

A given Diameter process SHOULD use the same port number to send all
messages to aid in identifying which process sent a given message.
More than one Diameter process MAY exist within a single host, so the
sender's port number is needed to discriminate them.

A summary of the Diameter data format is shown below.

When no transport connection exists with a peer, an attempt to
connect SHOULD be periodically attempted. The fields are
transmitted in network byte order. recommended connection
interval is 30 seconds.

2.2 Securing Diameter Messages

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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|r r r r r r r r r r E I R| Ver | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Command-Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVPs ...
+-+-+-+-+-+-+-+-+-+-+-+-+-

Flags
The Message Flags field is thirteen bits. The following bits are
assigned:

r(eserved)

All Diameter messages MUST be zero - this flag bit is reserved for
future use.
E(xpected Reply) - The message solicits a response.
I(nterrogation) - The message is a Query or a Reply.
R(esponse) - The message is a response to another message.

These flags secured between peers, and both SSL
[28] and IP Security [37] are set depending on the command code used in a
Diameter message. This enables the type of message supported. Network Access Servers
(NASes) and Foreign Agents, commonly referred to be
interpreted, even if as clients, MUST
support IP Security, while servers MUST support both SSL and IP
Security. The communication between a client and server MUST use IP
Security, while communication between servers MUST use SSL.

All hosts running the specific command code is not recognized.

Command Type Flags Set
Indication - - -
Request E - -
Answer - - R
Query E I -
Reply - I R

A Diameter node protocol MUST NOT set these flags in any other combination.
A have the necessary
security policies to ensure that unauthenticated Diameter node receiving a message in which these flags packets are
not
set appropriately SHOULD NOT reject the message processed.

2.3 Diameter Server Discovery

Allowing for this reason,
but MAY log the event dynamic Diameter server discovery will make it possible
for diagnosis.

Version
This Version field MUST be set simpler and more robust deployment of AAA services. In order to 1
promote interoperable implementations of Diameter server discovery,
the following mechanisms are described. These are based on existing
IETF standards.

There are two cases where Diameter server discovery may be performed.
The first is when a Diameter client needs to indicate discover a first-hop
Diameter Version
1.

Message Length server. The Message Length field second case is two octets and indicates the length when a Diameter server needs to
discover another server - for further handling of
the a Diameter message including
operation. In both cases, the header fields.

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Identifier
The Identifier field following 'search order' is four octets, and aids in matching requests
and replies.
recommended:

1. The sender MUST ensure that the identifier in a
request (*-Request or *-Query) or indication (*-Ind) message is
locally unique (to the sender) at any given time, Diameter implementation consults its list of static
(manual) configured Diameter server locations. These will be
used if they exist and MAY attempt respond.

2. The Diameter implementation uses SLPv2 [28] to ensure that the number is unique across reboots. discover
Diameter services. The sender of
a response (*-Answer or *-Response) MUST ensure Diameter service template [32] is
included in Appendix A. It is recommended that SLPv2 security
be deployed (this requires distributing keys to SLPv2 agents.)
This is discussed further in Appendix A.

SLPv2 will allow Diameter implementations to discover the
Identifier field contains the same Identifier value that was found
location of Diameter servers in the corresponding request. For The identifier is normally a
monotonically increasing number, whose start value was randomly
generated. local site, as well as
their characteristics. Diameter servers should consider a message to be unique
by examining with specific
capabilities (say support for the source address, source port, Session-Id Accounting extension) can be
requested, and
Identifier field of the message.

Command-Code only those will be discovered.

3. The Command-Code field is four octets, and is used in order Diameter implementation uses DNS to
communicate request the command associated with SRV RR [33]
for the message. The 32-bit
address space is managed by IANA (see section 9.2). '_diameter._sctp' and/or '_diameter._tcp' server in a
particular domain. The following
Command Codes are currently defined Diameter implementation has to know in the
advance which domain to look for an Diameter base protocol:

Command-Name Abbrev. Code Reference
--------------------------------------------------------
Device-Reboot-Ind DRI 257 2.6
Message-Reject-Ind MRI 259 5.1
Session-Termination-Ind STI 274 3.6.1
Session-Termination- STR 275 3.6.2
Request
Session-Termination- STA 276 3.6.3
Answer

Vendor-ID
In the event that server in. This
could be deduced, for example, from the Command-Code field contains 'realm' in a vendor
specific command, the four octet Vendor-ID field contains the IANA
assigned "SMI Network Management Private Enterprise Codes" [2]
value. If the Command-Code field contains NAI that

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an IETF standard
Command, Diameter implementation needed to perform an Diameter
operation on.

Diameter allows AAA peers to protect the Vendor-ID field MUST be set integrity and privacy
of communication as well as to zero (0).

AVPs
AVPs are perform end-point
authentication. Still, it is prudent to employ DNS Security as
a method of encapsulating information relevant precaution when using DNS SRV RRs to look up the location of
a Diameter message. See section 2.3 for more information on AVPs.

2.2 Command Code Message Definitions server. [34, 35, 36]

2.4 Mandatory Accounting Support

All Diameter Command Code implementations MUST include a corresponding ABNF
specification, which is used to define support the AVPs Diameter Accounting
Extension [15]. An implementation that MUST, MAY and
MUST does not support [15] does NOT be present. The following format is used in the definition:

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command-def = command-name "::=" diameter-message

diameter-name = ALPHA *(ALPHA / DIGIT / "-")

command-name = diameter-name
; The command-name has to be Command name,
; defined in
comply with the Diameter base or extended protocol.

3.0 Diameter Header

A summary of the Diameter
; specifications.

diameter-message = header [ *fixed] [ *required] [ *optional] [ *fixed] header = "<Diameter-Header:" command-id ">"

fixed = [qual] "<" avp-spec ">"

required = [qual] "{" avp-spec "}"

optional = [qual] "[" avp-name "]"
; format is shown below. The avp-name fields
are transmitted in the 'optional' rule cannot
; evaluate to any AVP Name which network byte order.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|r r r r r r r r r r E I R| Ver | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop-by-Hop Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| End-to-End Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Command-Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVPs ...
+-+-+-+-+-+-+-+-+-+-+-+-+-

Flags
The Message Flags field is included
; in a fixed or required rule.

qual = [min] "*" [max]
; See ABNF conventions, RFC 2234 section 3.6.
; thirteen bits. The absence of any qualifiers implies that one
; and only one such AVP following bits are
assigned:

r(eserved) MUST be present.
;
; NOTE: "[" and "]" have zero - this flag bit is reserved for
future use.
E(xpected Reply) - The message solicits a different meaning
; than response.
I(nterrogation) - The message is a Query or a Reply.
R(esponse) - The message is a response to another message.

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These flags are set depending on the command code used in ABNF (see a
Diameter message. This enables the optional rule, above).
; These braces cannot type of message to be used to express an
; optional fixed rules (such as an optional
; ICV at the end.) To do this,
interpreted, even if the convention
; specific command code is '0*1fixed'.

min = 1*DIGIT
; The minimum number of times the element may
; be present.

max = 1*DIGIT
; The maximum number of times the element may
; be present.

avp-spec = diameter-name
; The avp-spec has to be an AVP Name, defined
; not recognized.

Command Type Flags Set
Indication - - -
Request E - -
Answer - - R
Query E I -
Reply - I R

A Diameter node MUST NOT set these flags in the base or extended any other combination.
A Diameter
; specifications.

avp-name = avp-spec | "AVP"

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; The string "AVP" stands for *any* arbitrary
; AVP Name, node receiving a message in which does these flags are not conflict with
set appropriately SHOULD NOT reject the
; required or fixed position AVPs defined in
; message for this reason,
but MAY log the command code definition. event for diagnosis.

Version
This Version field MUST be set to 1 to indicate Diameter Version
1.

Message Length
The following Message Length field is a definition two octets and indicates the length of a fictitious command code:

Example-Command ::= < Diameter-Header: 9999999 >
{ User-Name }
* { Host-Name }
* [ AVP ]
0*1< Integrity-Check-Vector >

2.3 AVP Format
the Diameter AVPs carry specific authentication, accounting and
authorization information, security information as well as
configuration details for message including the request and reply.

Some AVPs MAY be listed more than once. header fields.

Hop-by-Hop Identifier
The effect of such an AVP Identifier field is
specific, four octets, and is specified aids in each case by the AVP description.

Each AVP of type OctetString matching requests
and replies. The sender MUST be padded to align on ensure that the identifier in a 32 bit
boundary, while other AVP types align naturally. NULL bytes are added
request (*-Request or *-Query) or indication (*-Ind) message is
locally unique (to the sender) at any given time, and MAY attempt
to ensure that the end number is unique across reboots. The sender of
a response (*-Answer or *-Response) MUST ensure that the AVP Data
Identifier field till a word boundary is reached. contains the same Identifier value that was found
in the corresponding request. For The
length identifier is normally a
monotonically increasing number, whose start value was randomly
generated. Diameter servers should consider a message to be unique
by examining the source address, source port, Session-Id and
Identifier field of the padding is not reflected in message.

End-to-End Identifier
Unlike the AVP Length Hop-by-Hop Identifier, the End-to-End Identifier is
used by servers to detect duplicate messages, and proxies MUST NOT
modify this field.

2.3.1 AVP Header The fields in the AVP header sender of a request, query, indication,
answer or response message MUST be sent insert a locally unique value in network byte order.
this field. The
format combination of the header is:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVP Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVP Length | Reserved |P|R|V|R|M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-ID (opt) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+-+-+-+-+

AVP Code
The AVP Code identifies the attribute uniquely. The first 256 Session-Id AVP and this field
is used to detect duplicates.

Command-Code

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numbers are reserved for backward compatibility with RADIUS and
are to be interpreted as per NASREQ [7]. AVP numbers 256

The Command-Code field is four octets, and above
are is used for Diameter, which are allocated in order to
communicate the command associated with the message. The 32-bit
address space is managed by IANA (see section
9.1).

AVP Length
The AVP Length field is two octets, and indicates 15.2).

Vendor-ID
In the length of
this AVP including event that the AVP Code, AVP Length, AVP Flags, Reserved, Command-Code field contains a vendor
specific command, the four octet Vendor-ID field (if present) and contains the AVP data. IANA
assigned "SMI Network Management Private Enterprise Codes" [2]
value. If a message is
received with the Command-Code field contains an invalid attribute length, IETF standard
Command, the message SHOULD be
rejected.

AVP Flags
The AVP Flags Vendor-ID field informs MUST be set to zero (0).

AVPs
AVPs are a method of encapsulating information relevant to the
Diameter host how each attribute
must be handled. Note that subsequent message. See section 4. for more information on AVPs.

3.1 Command Codes

Every Diameter extensions MAY
define bits to be message MUST contain a value in its header's Command-
Code field, which is used within to determine the AVP Header, and an unrecognized
bit should action that is to be considered an error. taken
for a particular message. The 'R' and the reserved bits following Command Codes are unused and should be set to 0 and ignored on receipt, while
the 'P' bit is defined in [11].

The 'M' Bit, known as the Mandatory bit, indicates whether support
of the AVP is required. If an AVP is received by a Home server or
NAS with the 'M' bit enabled and the receiver does not support
the AVP, the message MUST be rejected. If such an AVP is received
by a Proxy or Redirect Server,
the message MUST be forwarded to
its logical destination, and Diameter base protocol:

Command-Name Abbrev. Code Reference
--------------------------------------------------------
Device-Reboot-Ind DRI 257 6.1
Device-Status-Ind DSI 282 9.1
Device-Watchdog-Req DWR 280 7.1
Device-Watchdog-Answer DWA 281 7.2
Message-Reject-Ind MRI 259 10.1
Session-Termination-Ind STI 274 11.7.1
Session-Termination- STR 275 11.7.2
Request
Session-Termination- STA 276 11.7.3
Answer

Every Command Code defined MUST NOT be rejected. It is the
responsibility of the originator of include a message that corresponding ABNF
specification, which is rejected for
this purpose used to correct define the error. AVPs without the 'M' bit
enabled are informational only and a receiver that receives a
message with such an AVP that is not supported MUST, MAY simply ignore
the AVP.

The 'V' bit, known as the Vendor-Specific bit, indicates whether
the optional Vendor-ID field is present in the AVP header. When
set the AVP Code belongs to the specific vendor code address
space.

Unless otherwise noted, AVPs will have the following default AVP
Flags field settings:
The 'M' bit MUST be set. The 'V' bit and
MUST NOT be set.

2.3.2 Optional Header Elements present. The AVP Header contains one optional field. This field following format is only
present if used in the respective bit-flag is enabled.

Vendor-ID

Calhoun definition:

command-def = command-name "::=" diameter-message

diameter-name = ALPHA *(ALPHA / DIGIT / "-")

command-name = diameter-name
; The command-name has to be Command name,
; defined in the base or extended Diameter
; specifications.

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diameter-message = header [ *fixed] [ *required] [ *optional] [ *fixed]

header = "<Diameter-Header:" command-id ">"

fixed = [qual] "<" avp-spec ">"

required = [qual] "{" avp-spec "}"

optional = [qual] "[" avp-name "]"
; The Vendor-ID field is present if the 'V' bit is set avp-name in the AVP
Flags field. The optional four octet Vendor-ID field contains the
IANA assigned "SMI Network Management Private Enterprise Codes"
[2] value, encoded in network byte order. Any vendor wishing 'optional' rule cannot
; evaluate to
implement a Diameter extension MUST use their own Vendor-ID along
with their privately managed AVP address space, guaranteeing that
they will not collide with any other vendor's extensions, nor with
future IETF extensions.

A vendor ID value of zero (0) corresponds to the IETF adopted AVP
values, as managed by the IANA. Since the Name which is included
; in a fixed or required rule.

qual = [min] "*" [max]
; See ABNF conventions, RFC 2234 section 6.6.
; The absence of the vendor ID
field any qualifiers implies that the one
; and only one such AVP MUST be present.
;
; NOTE: "[" and "]" have a different meaning
; than in question is not vendor specific,
implementations SHOULD not use ABNF (see the zero (0) vendor ID.

2.3.3 AVP Data Formats

The Data field is zero or more octets and contains information
specific optional rule, above).
; These braces cannot be used to express an
; optional fixed rules (such as an optional
; ICV at the Attribute. The format and length of end.) To do this, the Data field convention
; is
determined by the AVP Code and AVP Length fields. '0*1fixed'.

min = 1*DIGIT
; The format minimum number of times the
Data field MAY element may
; be one of the following data types. present.

max = 1*DIGIT
; The interpretation of the values depends on the specification maximum number of times the
AVP. For example, an OctetString element may
; be used present.

avp-spec = diameter-name
; The avp-spec has to transmit human
readable string data and Unsigned32 may be used to transmit a time
value. Conventions for these common interpretations are described
below.

OctetString an AVP Name, defined
; in the base or extended Diameter
; specifications.

avp-name = avp-spec | "AVP"
; The data contains string "AVP" stands for *any* arbitrary data of variable length. Unless
otherwise noted, the
; AVP Length field MUST be set to at least 9
(13 if Name, which does not conflict with the 'V' bit is enabled). Data used to transmit (human
readable) character string data uses
; required or fixed position AVPs defined in
; the UTF-8 [24] character
set and is NOT NULL-terminated. command code definition.

The minimum Length field MUST
be 9, but can be set to any value up to 65527 bytes. AVP Values following is a definition of this type that do not align on a 32-bit boundary MUST adding
necessary padding.

Address
32 bit (IPv4) [17] or 128 bit (IPv6) [16] address, most
significant octet first. fictitious command code:

Example-Command ::= < Diameter-Header: 9999999 >
{ User-Name }

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* { Origin-FQDN }
* [ AVP ]
0*1< Integrity-Check-Vector >

4.0 Diameter AVPs

Diameter AVPs carry specific authentication, accounting and
authorization information, security information as well as
configuration details for the request and reply.

Some AVPs MAY be listed more than once. The format effect of the address (IPv4 or
IPv6) is determined by the length. If the attribute value is such an
IPv4 address, the AVP Length field MUST be 12 (16 if 'V' bit is
enabled), otherwise
specific, and is specified in each case by the AVP Length field description.

Each AVP of type OctetString MUST be set padded to 24 (28
if the 'V' bit is enabled) for IPv6 addresses.

Integer32 align on a 32 bit signed value, in network byte order. The
boundary, while other AVP Length

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field MUST be set types align naturally. NULL bytes are added
to 12 (16 if the 'V' bit end of the AVP Data field till a word boundary is enabled).

Integer64
64 bit signed value, in network byte order. reached. The
length of the padding is not reflected in the AVP Length
field field.

4.1 AVP Header

The fields in the AVP header MUST be set to 16 (20 if the 'V' bit is enabled).

Unsigned32
32 bit unsigned value, sent in network byte order. The AVP Length
field MUST be set to 12 (16 if the 'V' bit is enabled).
Unsigned32 values used to transmit time data contains
format of the four
most significant octets returned from NTP [18], in network byte
order.

Unsigned64
32 bit unsigned value, in network byte order. The header is:

Float32
This represents floating point values of single precision as
described by [30]. | Reserved |P|r|V|r|M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-ID (opt) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+-+-+-+-+

AVP Code
The 32 bit value is transmitted in network
byte order. AVP Code identifies the attribute uniquely. The first 256 AVP Length field MUST be set
numbers are reserved for backward compatibility with RADIUS and
are to 12 (16 if the
'V' bit is enabled).

Float64
This represents floating point values of double precision be interpreted as
described per NASREQ [7]. AVP numbers 256 and above
are used for Diameter, which are allocated by [30]. The 64 bit value is transmitted in network
byte order. IANA (see section
15.1).

AVP Length
The AVP Length field MUST be set to 16 (20 if the
'V' bit is enabled).

Float128
This represents floating point values two octets, and indicates the length of quadruple precision as
described by [30]. The 128 bit value is transmitted in network
byte order. The
this AVP Length including the AVP Code, AVP Length, AVP Flags, Reserved,
the Vendor-ID field MUST be set to 24 (28 if (if present) and the
'V' bit AVP data. If a message is enabled).

Grouped

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received with an invalid attribute length, the message SHOULD be
rejected.

AVP Flags
The Data AVP Flags field is specified as a sequence of AVPs. Each of
these AVPs follows - in informs the order in which they are specified -
including their headers Diameter host how each attribute
must be handled. Note that subsequent Diameter extensions MAY
define bits to be used within the AVP Header, and padding. an unrecognized
bit should be considered an error. The AVP Length field is 'r' and the reserved bits
are unused and should be set to 8 (12 if 0 and ignored on receipt, while
the 'V' 'P' bit is enabled) plus defined in [11].

The 'M' Bit, known as the total length Mandatory bit, indicates whether support
of all included AVPs, including their headers.

2.3.4 Grouped the AVP Values

The Diameter protocol allows is required. If an AVP values of type 'Grouped.' This
implies that the Data field is actually received by a well defined sequence of
AVPs. It is possible to include Home server or
NAS with the 'M' bit enabled and the receiver does not support
the AVP, the message MUST be rejected. If such an AVP with is received
by a Grouped type within Proxy or Redirect Server, the message MUST be forwarded to
its logical destination, and MUST NOT be rejected. It is the
responsibility of the originator of a

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Grouped type, message that is, is rejected for
this purpose to nest them. AVPs within an AVP of type
Grouped have correct the same padding requirements as non-Grouped AVPs, error. AVPs without the 'M' bit
enabled are informational only and a receiver that receives a
message with such an AVP that is not supported MAY simply ignore
the AVP.

The 'V' bit, known as
defined the Vendor-Specific bit, indicates whether
the optional Vendor-ID field is present in section 2.3.

Grouped type the AVP specifications include an ABNF grammar [31]
specifying header. When
set the required sequence of AVPs. Grouped AVP values Code belongs to the specific vendor code address
space.

Unless otherwise noted, AVPs will have the following default AVP
Flags field settings:
The 'M' bit MUST be
in the specified sequence and set. The 'V' bit MUST NOT include other AVP values
besides those specified by the Grouped AVP grammar.

2.3.4.1 Example AVP with a Grouped Data type be set.

4.2 Optional Header Elements

The Example AVP (AVP Code 999999) Header contains one optional field. This field is of type Grouped and only
present if the respective bit-flag is used to
clarify how Grouped AVP values work. enabled.

Vendor-ID
The Grouped Data Vendor-ID field has is present if the 'V' bit is set in the
following ABNF grammar:

example-avp-val = Host-Name Host-IP-Address
Host-Name = ; See Section 2.4.1
Host-IP-Address = ; See Section 2.6.4

An Example AVP with
Flags field. The optional four octet Vendor-ID field contains the Grouped Data Host-Name = "example.com",
Host-IP-Address = "10.10.10.10" would be
IANA assigned "SMI Network Management Private Enterprise Codes"
[2] value, encoded as follows:

0 1 2 3 4 5 6 7
+-------+-------+-------+-------+-------+-------+-------+-------+
0 | Example in network byte order. Any vendor wishing to
implement a Diameter extension MUST use their own Vendor-ID along
with their privately managed AVP Header (AVP Code = 999999), Length = 40 |
+-------+-------+-------+-------+-------+-------+-------+-------+
8 | Host-Name AVP Header (AVP Code = 265), Length = 19 |
+-------+-------+-------+-------+-------+-------+-------+-------+
16 | 'e' | 'x' | 'a' | 'm' | 'p' | 'l' | 'e' | '.' |
+-------+-------+-------+-------+-------+-------+-------+-------+
24 | 'c' | 'o' | 'm' |Padding| Host-IP-Addr AVP Header |
+-------+-------+-------+-------+-------+-------+-------+-------+
32 | (AVP Code = 257), Length = 12 | 0x0a | 0x0a | 0x0a | 0x0a |
+-------+-------+-------+-------+-------+-------+-------+-------+

2.3.5 Diameter Base Protocol AVPs

The following table describes the Diameter AVPs defined in the base
protocol, their AVP Code values, types, possible flag values and
whether the AVP MAY be encrypted. address space, guaranteeing that
they will not collide with any other vendor's extensions, nor with
future IETF extensions.

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+---------------------+
|

A vendor ID value of zero (0) corresponds to the IETF adopted AVP Flag rules |
|----+-----+----+-----|----+
values, as managed by the IANA. Since the absence of the vendor ID
field implies that the AVP in question is not vendor specific,
implementations SHOULD not use the zero (0) vendor ID.

4.3 AVP Data Formats

The Data field is zero or more octets and contains information
specific to the Attribute. The format and length of the Data field is
determined by the AVP Section | | |SHLD| MUST|MAY |
Attribute Name Code Defined and AVP Length fields. The format of the
Data Type |MUST| field MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----|
Authentication- 285 7.1.1.1 Unsigned32 | | | | | N |
Transform-Id | | | | | |
Authorization- 291 3.3 Unsigned32 | | | | | N |
Lifetime | | | | | |
Destination-NAI 293 6.8 OctetString| | | | | Y |
Digest 287 7.1.1.2 OctetString| | | | | N |
Encrypted-Data 290 7.1.2.3 OctetString| | | | | N |
Encrypted- 260 7.1.2 Grouped | M | | | | N |
Payload | | | | | |
Encryption- 288 7.1.2.1 be one of the following data types.

The interpretation of the values depends on the specification of the
AVP. For example, an OctetString may be used to transmit human
readable string data and Unsigned32 | | | | | N |
Transform-Id | | | | | |
Error-Message 281 5.3 OctetString| | | | | N |
Error-Reporting- 294 may be used to transmit a time
value. Conventions for these common interpretations are described
below.

OctetString
The data contains arbitrary data of variable length. Unless
otherwise noted, the AVP Length field MUST be set to at least 9
(13 if the 'V' bit is enabled). Data used to transmit (human
readable) character string data uses the UTF-8 [24] character
set and is NOT NULL-terminated. The minimum Length field MUST
be 9, but can be set to any value up to 65527 bytes. AVP Values
of this type that do not align on a 32-bit boundary MUST have
the necessary padding.

Address
32 bit (IPv4) [17] or 128 bit (IPv6) [16] address, most
significant octet first. The format of the address (IPv4 or
IPv6) is determined by the length. If the attribute value is an
IPv4 address, the AVP Length field MUST be 12 (16 if 'V' bit is
enabled), otherwise the AVP Length field MUST be set to 24 (28
if the 'V' bit is enabled) for IPv6 addresses.

Integer32
32 bit signed value, in network byte order. The AVP Length
field MUST be set to 12 (16 if the 'V' bit is enabled).

Integer64
64 bit signed value, in network byte order. The AVP Length
field MUST be set to 16 (20 if the 'V' bit is enabled).

Unsigned32
32 bit unsigned value, in network byte order. The AVP Length
field MUST be set to 12 (16 if the 'V' bit is enabled).

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Unsigned32 values used to transmit time data contains the four
most significant octets returned from NTP [18], in network byte
order.

Unsigned64
32 bit unsigned value, in network byte order. The AVP Length
field MUST be set to 16 (20 if the 'V' bit is enabled).

Float32
This represents floating point values of single precision as
described by [30]. The 32 bit value is transmitted in network
byte order. The AVP Length field MUST be set to 12 (16 if the
'V' bit is enabled).

Float64
This represents floating point values of double precision as
described by [30]. The 64 bit value is transmitted in network
byte order. The AVP Length field MUST be set to 16 (20 if the
'V' bit is enabled).

Float128
This represents floating point values of quadruple precision as
described by [30]. The 128 bit value is transmitted in network
byte order. The AVP Length field MUST be set to 24 (28 if the
'V' bit is enabled).

Grouped
The Data field is specified as a sequence of AVPs. Each of
these AVPs follows - in the order in which they are specified -
including their headers and padding. The AVP Length field is
set to 8 (12 if the 'V' bit is enabled) plus the total length
of all included AVPs, including their headers.

4.4 Grouped AVP Values

The Diameter protocol allows AVP values of type 'Grouped.' This
implies that the Data field is actually a well defined sequence of
AVPs. It is possible to include an AVP with a Grouped type within a
Grouped type, that is, to nest them. AVPs within an AVP of type
Grouped have the same padding requirements as non-Grouped AVPs, as
defined in section 4.0.

Grouped type AVP specifications include an ABNF grammar [31]
specifying the required sequence of AVPs. Grouped AVP values MUST be
in the specified sequence and MUST NOT include other AVP values
besides those specified by the Grouped AVP grammar.

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4.4.1 Example AVP with a Grouped Data type

The Example AVP (AVP Code 999999) is of type Grouped and is used to
clarify how Grouped AVP values work. The Grouped Data field has the
following ABNF grammar:

example-avp-val = Origin-FQDN Host-IP-Address
Origin-FQDN = ; See Section 5.1
Host-IP-Address = ; See Section 6.1.4

An Example AVP with the Grouped Data Origin-FQDN = "example.com",
Host-IP-Address = "10.10.10.10" would be encoded as follows:

0 1 2 3 4 5 6 7
+-------+-------+-------+-------+-------+-------+-------+-------+
0 | Example AVP Header (AVP Code = 999999), Length = 40 |
+-------+-------+-------+-------+-------+-------+-------+-------+
8 | Origin-FQDN AVP Header (AVP Code = 265), Length = 19 |
+-------+-------+-------+-------+-------+-------+-------+-------+
16 | 'e' | 'x' | 'a' | 'm' | 'p' | 'l' | 'e' | '.' |
+-------+-------+-------+-------+-------+-------+-------+-------+
24 | 'c' | 'o' | 'm' |Padding| Host-IP-Addr AVP Header |
+-------+-------+-------+-------+-------+-------+-------+-------+
32 | (AVP Code = 257), Length = 12 | 0x0a | 0x0a | 0x0a | 0x0a |
+-------+-------+-------+-------+-------+-------+-------+-------+

4.5 Diameter Base Protocol AVPs

The following table describes the Diameter AVPs defined in the base
protocol, their AVP Code values, types, possible flag values and
whether the AVP MAY be encrypted.

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+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
AVP Section | | |SHLD| MUST|MAY |
Attribute Name Code Defined Data Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----|
Encrypted-Data 290 13.1.2.3 OctetString| | | | | N |
Encrypted- 260 13.1.2 Grouped | M | | | | N |
Payload | | | | | |
Encryption- 288 13.1.2.1 Unsigned32 | | | | | N |
Transform-Id | | | | | |
Error-Message 281 10.3 OctetString| | | | | N |
Error-Reporting- 294 10.4 OctetString| | | | | Y |
FQDN | | | | | |
Extension-Id 258 6.1.3 Integer32 | M | | | | Y |
Failed-AVP 279 10.1.1 OctetString| | | | | Y |
Failed-Command- 270 10.1.2 Unsigned32 | | | | | Y |
Code | | | | | |
Firmware 267 6.1.2 Unsigned32 | | | | V,M | Y |
-Revision | | | | | |
Host-IP-Address 257 6.1.4 Address | M | | | V | N |
Origin-FQDN 264 5.1 OctetString| M | | | V | N |
Integrity-Check 259 13.1.1 Grouped | M | | | | N |
-Value | | | | | |
Key-Id 286 13.4 Unsigned32 | | | | | N |
Max-Wait-Time 295 11.6 Unsigned32 | M | | | V | N |
Nonce 261 13.2 OctetString| | | | | N |
Origin-Realm 296 5.2 OctetString| M | | | V | N |
Plaintext-Data- 289 13.1.2.2 Unsigned32 | | | | | N |
Length | | | | | |
Proxy-Address 280 12.4.5 Address | M | | | V | N |
Proxy-Info 284 12.4.6 OctetString| M | | | V | N |
Proxy-State 33 12.4.4 Grouped | M | | | V | N |
Redirect-Host 292 12.3.1 Grouped | | | | | Y |
Redirect-Host- 278 12.3.2 Address | | | | | Y |
Address | | | | | |
Redirect-Host- 277 12.3.3 Unsigned32 | | | | | Y |
Port | | | | | |
Result-Code 268 10.2 Unsigned32 | M | | | | N |
Route-Record 282 12.4.3 OctetString| M | | | V | N |
Destination- 283 12.4.7 OctetString| M | | | V | N |
Realm | | | | | |
Session-Id 263 11.2 OctetString| M | | | | Y |
Session-Timeout 27 11.4 Unsigned32 | | | | | Y |
Timestamp 262 13.3 Unsigned32 | | | | | N |
User-Name 1 11.5 OctetString| | | | | Y |
Vendor-Id 266 6.1.1 Unsigned32 | | | | V,M | Y |
-----------------------------------------|----+-----+----+-----|----|

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5.0 Message Forwarding

All Diameter messages MUST include the Origin-FQDN and Origin-Realm
AVPs. These AVPs are used to identify the source of the message.
When responding to a request or query message, the Origin-FQDN and
Origin-Realm AVPs are replaced with the local node's information.

When a Diameter entity receives a Diameter message of type Request,
Query or Indication that includes a Destination-FQDN AVP, and the
host specified in the AVP can be contacted directly, the message MUST
be forwarded to the host in question.

The Destination-FQDN AVP is used when the destination of the message
is fixed, such as:

- Authentication requests that span multiple round trips
- A Diameter message that uses a security mechanism that makes use
of a pre-established session key shared between the source and
the final destination of the message.
- Server initiated messages that MUST be received by a specific
Diameter client (e.g. NAS), such as the Session-Termination-Ind
message, which is used to request that a particular user's
session be terminated.

Proxies receiving messages that contain the Destination-FQDN AVP MUST
verify whether they are able to forward Diameter messages to the host
specified in the AVP, and if so, MUST forward the message to the host
in question. Otherwise, the message routing procedures described in
section 12.0 MUST be followed.

This section defines the Diameter AVPs that MUST be added in all
messages originated by a Diameter node (including nodes creating
Response and Answer messages).

5.1 Origin-FQDN AVP

The Origin-FQDN AVP (AVP Code 264) is of type OctetString, encoded in
the UTF-8 [24] format. This AVP identifies the endpoint which
originated the Diameter message, i.e. the NAS, home server, or
broker. Proxy servers do not modify this AVP. All Diameter messages
MUST include the Origin-FQDN AVP, which contains the host name of the
originator of the Diameter message and MUST follow the NAI [8] naming
conventions.

Note that the Origin-FQDN AVP may resolve to more than one address as
the Diameter peer may support more than one address.

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5.2 Origin-Realm AVP

The Origin-Realm AVP (AVP Code 296) is of type OctetString, encoded
in the UTF-8 [24] format. This AVP contains the Realm of the
originator of any Diameter message.

5.3 OctetString| | | | | Y |
NAI | | | | | | Destination-FQDN AVP

The Destination-FQDN AVP (AVP Code 293) is of type OctetString,
encoded in the UTF-8 [24] format, and contains the Fully Qualified
Domain Name (FQDN) of the intended recipient of the message. This AVP
MUST be present in all unsolicited server initiated messages. The
value of the Destination-FQDN AVP is set to the value of the Origin-
FQDN AVP found in a message from the intended target host.

6.0 Capabilities Exchange

When two Diameter peers establish a transport connection, they MUST
send the Device-Reboot-Ind message. This message has two purposes.
First it allows a peer's identity to be discovered, and allows for
capabilities exchange, such as the supported protocol version number,
and the locally supported extensions.

The receiver uses the extensions advertised in order to determine
whether it SHOULD send certain application-specific Diameter
commands. A Diameter node MUST retain the supported extensions in
order to ensure that unrecognized commands and/or AVPs are not sent
to a peer.

The Device-Reboot-Ind message MUST NOT be proxied, or redirected.

Since the DRI cannot be proxied, it is still possible that a upstream
proxy receives a message for which it has no available peers to
handle the extension that corresponds to the Command-Code. In such
instances, the Device-Status-Ind message is used (see Section 9.1) to
inform the downstream to take action.

With the exception of the Device-Reboot-Ind message, a message of
type Request, Query or Indication that includes the Extension-Id 258 2.6.3 Integer32 | M | | | | Y |
Failed-AVP 279 5.1.1 OctetString| | | | | Y |
Failed-Command- 270 5.1.2 Unsigned32 | | | | | Y |
Code | | | | | |
Firmware 267 2.6.2 Unsigned32 | | | | V,M | Y |
-Revision | | | | | |
Host-IP-Address 257 2.6.4 Address | M | | | V | N |
Host-Name 264 2.4.1 OctetString| M | | | V | N |
Integrity-Check 259 7.1.1 Grouped | M | | | | N |
-Value | | | | | |
Key-Id 286 7.4 Unsigned32 | | | | | N |
Nonce 261 7.2 OctetString| | | | | N |
Plaintext-Data- 289 7.1.2.2 Unsigned32 | | | | | N |
Length | | | | | |
Proxy-Address 280 6.4.5 Address | M | | | V | N |
Proxy-Info 284 6.4.6 OctetString| M | | | V | N |
Proxy-State 33 6.4.4 Grouped | M | | | V | N |
Redirect-Host 292 6.3.1 Grouped | | | | | Y |
Redirect-Host- 278 6.3.2 Address | | | | | Y |
Address | | | | | |
Redirect-Host- 277 6.3.3 Unsigned32 | | | | | Y |
Port | | | | | |
Result-Code 268 5.2 AVP
MAY only be forwarded to a host that has explicitely advertised
support for the extension (or has advertised the Wildcard Extension).

6.1 Device-Reboot-Ind (DRI) Command

The Device-Reboot-Ind (DRI), indicated by the Command-Code set to

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257, is sent to inform a peer that a reboot has, or will, occur.

When Diameter is run over SCTP [26], which allows for connections to
span multiple interfaces, hence multiple IP addresses, the Device-
Reboot-Ind message MUST contain one Host-IP-Address AVP for each
potential IP address that MAY be locally used when transmitting
Diameter messages.

If a Diameter node receives a DRI message that results in an error, a
Message-Reject-Ind message MUST be returned.

Message Format

<Device-Reboot-Ind> ::= < Diameter Header: 257 >
{ Origin-FQDN }
{ Origin-Realm }
1* { Host-IP-Address }
{ Vendor-Id }
* { Extension-Id }
[ Firmware-Revision ]
* [ AVP ]
0*1< Integrity-Check-Value >

6.1.1 Vendor-Id AVP

The Vendor-Id AVP (AVP Code 266) is of type Unsigned32 | M | | | | N |
Route-Record 282 6.4.3 OctetString| M | | | V | N |
Routing-Realm 283 6.4.7 OctetString| M | | | V | N |
Session-Id 263 3.2 OctetString| | | | | Y |
Session-Timeout 27 3.6 and contains
the IANA assigned "SMI Network Management Private Enterprise Codes"
[2] value of the Diameter device.

This MAY be used in order to know which vendor specific attributes
may be sent to the peer. It is also envisioned that the combination
of the Vendor-Name and the Firmware-Revision (section 6.1.2) AVPs MAY
provide very useful debugging information.

6.1.2 Firmware-Revision AVP

The Firmware-Revision AVP (AVP Code 267) is of type Unsigned32 | | | | | Y | and is
used to inform a Diameter peer of the firmware revision of the
issuing device.

For devices that do not have a firmware revision (general purpose
computers running Diameter software modules, for instance), the
revision of the Diameter software module may be reported instead.

6.1.3 Extension-Id AVP

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+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+

The Extension-Id AVP Section | | |SHLD| MUST|MAY |
Attribute Name (AVP Code Defined Data Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----|
Timestamp 262 7.3 Unsigned32 | | | | | N |
User-Name 1 3.5 OctetString| | | | | Y |
Vendor-Id 266 2.6.1 258) is of type Unsigned32 | | | | V,M | Y |
-----------------------------------------|----+-----+----+-----|----|

2.4 Mandatory AVPs and is used
in order to identify a specific Diameter extension. This section defines AVP is used
in the Diameter AVPs that Device-Reboot-Ind message in order to inform the peer what
extensions are locally supported. The Extension-Id MUST also be
present in all messages that are defined in a separate Diameter messages.

2.4.1 Host-Name
specification and have an Extension ID assigned.

Each Diameter extension draft MUST have an IANA assigned extension
Identifier (see section 15.3). The base protocol does not require an
Extension-Id since its support is mandatory.

There MAY be more than one Extension-Id AVP within a Diameter
Device-Reboot-Ind message. The following values are recognized:

NASREQ 1 [7]
Strong Security 2 [11]
Resource Management 3 [29]
Mobile-IP 4 [10]
Accounting 5 [15]
Wildcard Extension 0xffffffff

Servers acting as Redirect or Proxy servers (see Section 12.0) MAY
wish to either advertise all supported extensions, or the wildcard
extension. The receiver of a wildcard extension MUST assume that the
sender supports all extensions.

Proxy servers are responsible for finding a downstream server that
supports the extension of a particular message. If none can be found,
a DSI message is returned with the DSI-Event AVP set to
DIAMETER_UNABLE_TO_DELIVER.

6.1.4 Host-IP-Address AVP

The Host-Name Host-IP-Address AVP (AVP Code 264) [1] 257) is of type OctetString. This AVP
identifies the endpoint which originated the Diameter message, i.e. the
NAS, home server, or broker. Proxy servers do not modify this AVP.
All Diameter messages MUST include the Host-Name AVP, which contains the
host name of the originator of the Diameter message Address and MUST follow
the NAI [8] naming conventions.

Note that the Host-Name AVP may resolve is used
to more than one address
as the inform a Diameter peer may support more than one of the sender's IP address.

2.5 State Machine

This section contains a finite state machine, All source
addresses that MUST be observed
by all Diameter implementations. Each a Diameter node MUST follow the
state machine described below when communicating with each peer.

State Event Action New State
----- ----- ------ ---------
Initial Local request expects to establish SCTP Idle
communication with a Diameter Connect
peer use with which there is no
existing transport level
connection established.

Initial Receive transport level Send DRI Wait-DRI
connection request from SCTP [26] MUST be
advertised in the Device-Reboot-Ind message by including a
Diameter peer.

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Idle Connection Established Send DRI Wait-DRI

Idle Receive DRI Send DRI Open

Wait-DRI Receive DRI None Open

Open Receive other messages Process Open
Message

Open Receive DRI Cleanup Closed

Open Transport level failure Cleanup Closed

Closed Diameter Entity shutdown Close Initial
or close connection with peer connection

The Initial and Idle states MAY Host-IP-
Address AVP for each address. This AVP MUST ONLY be merged if used in the local SCTP
implementation is able to implement
Device-Reboot-Ind message.

7.0 Transport Failure Detection

Given the piggyback nature of data during the
connection phase.

When the Cleanup action Diameter protocol, it is invoked, recommended that
transport failures be detected as soon as possible. Detecting such
failures will minimize the Diameter node SHOULD attempt occurrence of messages sent to forward all pending requests unavailable
servers, resulting in unnecessary delays, and replies, which haven't been
acknowledged, will provide better

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failover performance.

In order to an alternate server (when possible). If pro-actively detect such failures, the final
destination for a specific message is Diameter protocol
defines the host that Device-Watchdog-Request message, which is sent to an
inactive peer. A peer is considered inactive if no longer
accessible, messages were sent
or received from the message in question SHOULD be responded peer within the current watchdog interval period
(see Section 17.0), and no request or query messages are pending with
the
Result-Code AVP set peer.

For implementations that have access to DIAMETER_UNABLE_TO_DELIVER.

2.6 Device-Reboot-Ind (DRI) Command

A Diameter device sends the Device-Reboot-Ind message, by setting the
Command-Code field with a Retransmission Time-Out
(RTO) value of 257, to inform the underlying transport connection, a peer DWR SHOULD be
sent once per RTO of that connection, plus the watchdog interval
period, with a
reboot has just occurred. Since SCTP [26] allows for connections to
span multiple interfaces, hence multiple IP addresses, jiterring of +/- 50%.

If the Device-
Reboot-Ind message DWR is unanswered, the time until the next DWR is sent MUST contain one Host-IP-Address AVP for each
potential IP address that MAY be locally used when transmitting
Diameter messages.

The DRI message is also used for capabilities negotiation, such as
recalculated after exponentially backing off the supported protocol version number, RTO portion. When
the value of the DWR's current watchdog interval period reaches the
maximum watchdog interval (Secton 17.0), backoff is not continued,
and the locally supported
extensions. peer is marked as failed. DWR messages continue to be sent
(jittered) at the final interval for detection for failover. The receiver uses the extensions advertised in order
current watchdog interval is returned to
determine whether it SHOULD send certain application-specific
Diameter commands. A Diameter node MUST retain its starting point when a
DWA is received or the supported
extensions in order to ensure peer resumes activity.

Implementations that unrecognized commands and/or AVPs
are do not sent have access to the RTO SHOULD perform an
Round Trip Time (RTT) measurement for a peer. Note that in given peer when a proxy environment, it Device-
Watchdog-Answer message is still
possible that received for a downstream proxy has no available peer that have
advertised non-backed off DWR. The
fixed RTO base should be replaced by RTT-Multiplier (Section 17.0)
times the extension measured RTT.

An example of the backoff sequence, excluding jitter, would be:
30+RTO , 30+2*RTO , 30+4*RTO , 30+8*RTO, 60, 60, 60

Note that corresponds to exponential backoff MUST be performed before the maximum is
reached.

7.1 Device-Watchdog-Request

The Device-Watchdog-Request (DWR), indicated by the Command-Code, Command-Code set
to 280, is sent to a peer when no traffic has been exchanged between
two peers as defined in Section 7.0, and
therefore no requests are pending with
the request cannot be forwarded any further. The Diameter peer.

Message Format

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base protocol provides this error reporting, via the Result-Code AVP.

Once the transport layer connection has been established, a

<Device-Watchdog-Request> ::= < Diameter
entity MUST issue a DRI message, regardless of whether Header: 280 >
{ Origin-FQDN }
{ Origin-Realm }
0*1< Integrity-Check-Value >

7.2 Device-Watchdog-Answer

The Device-Watchdog-Answer (DWA), indicated by the peer was
statically configured, or dynamically discovered (see Section 2.7 for
more information).

If a peer Command-Code set
to 281, is no longer reachable, sent as a Diameter device SHOULD
periodically attempt response to establish a transport level connection with the peer and send a DRI Device-Watchdog-Request message. This message does not require a
reply. If a Diameter node receives a DRI message that results
A receiver of the DWA SHOULD perform RTT calculation in an
error, a Message-Reject-Ind message MUST be returned. the event
that the transport RTO information is not available.

Message Format

<Device-Reboot-Ind>

<Device-Watchdog-Answer> ::= < Diameter Header: 257 281 >
{ Host-Name }
1* { Host-IP-Address Result-Code }
{ Vendor-Id Origin-FQDN }
*
{ Extension-Id Origin-Realm }
[ Firmware-Revision ]
* [ AVP ]
0*1< Integrity-Check-Value >

2.6.1 Vendor-Id AVP

The Vendor-Id AVP (AVP Code 266)

7.3 Failover/Failback Procedures

In the event that a transport failure is of type Unsigned32 detected with a peer, it is
necessary for all pending request, query and contains
the IANA assigned "SMI Network Management Private Enterprise Codes"
[2] value of the Diameter device.

This MAY be used in order indication messages to know which vendor specific attributes
may
be sent forwarded to an alternate server, if possible. This is commonly
referred to as failover.

In order for a Diameter node to perform failover procedures, it is
necessary for the node to maintain a pending message queue for a
given peer. It When a response is also envisioned that the combination
of received, the Vendor-Name and message is removed from
the Firmware-Revision (section 2.6.2) AVPs MAY
provide very useful debugging information.

2.6.2 Firmware-Revision AVP queue. The Firmware-Revision AVP (AVP Code 267) Hop-by-Hop Identifier field MAY be used to match the
corresponding response with the queued response.

When a transport failure is detected, all messages in the queue are
sent to an alternate server, if possible. An example of type Unsigned32 and a case where
it is
used not possible for forward the message to inform an alternate server is
when the message has a Diameter peer of fixed destination, and the firmware revision of unavailable peer is
the
issuing device.

For devices message's final destination (see Destination-FQDN AVP). Such an
error requires that do not have a firmware revision (general purpose
computers running Diameter software modules, for instance), the
revision of server return an DSI with the DSI-Event AVP
set to DIAMETER_UNABLE_TO_DELIVER.

As described in section 2.1, a connection request should be
periodically attempted with the failed peer in order to re-establish
the Diameter software module may transport connection. Once a connection has been successfully
established, messages can once again be reported instead. forwarded to the peer. This
is commonly referred to as failback.

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2.6.3 Extension-Id AVP

The Extension-Id AVP (AVP Code 258) is of type Unsigned32 and is used
in order to identify a specific Diameter extension.

8.0 Peer State Machine

This AVP is used
in the Device-Reboot-Ind message in order to inform the peer what
extensions are locally supported. The Extension-Id section contains a finite state machine, that MUST also be
present in observed
by all messages that are defined in a separate Diameter
specification and have an Extension ID assigned. implementations. Each Diameter extension draft node MUST have an IANA assigned extension
Identifier (see section 9.3). The base protocol does not require an
Extension-Id since its support is mandatory.

There MAY be more than one Extension-Id AVP within a Diameter
Device-Reboot-Ind message. The following values are recognized:

NASREQ 1 [7]
Strong Security 2 [11]
Resource Management 3 [29]
Mobile-IP 4 [10]
Accounting 5 [15]

Furthermore, servers acting as Redirect or Proxy servers (see Section
6.0) MAY wish to advertise support for ALL possible extensions. Such
servers are then responsible for finding a downstream server that
supports the extension of a particular message. This is done by
including follow the Extension-Id AVP with a value of zero (0).

2.6.4 Host-IP-Address AVP

The Host-IP-Address AVP (AVP Code 257) [1] is of type Address and is
used
state machine described below when communicating with each peer.

State Event Action New State
----- ----- ------ ---------
Initial Local request to inform establish SCTP/TCP Idle
communication with a Diameter Connect
peer of the sender's IP address. All
source addresses that a Diameter node expects to use with SCTP [26]
MUST be advertised in the Device-Reboot-Ind message by including which there is no
existing transport level
connection established.

Initial Receive transport level Send DRI Wait-DRI
connection request from a
Host-IP-Address AVP for each address. This AVP MUST ONLY be used in
the Device-Reboot-Ind message.

2.7
Diameter Server Discovery

Allowing for dynamic peer.

Idle Connection Established Send DRI Wait-DRI

Idle Receive DRI Send DRI + Open
Reset Watchdog
Timer

Wait-DRI Receive DRI Reset Watchdog Open
Timer

Open Receive other messages Process Open
Message +
Reset Watchdog
Timer

Open Idle link, and no pending Send DWR Open
requests

Open Receive DWR Send DWA Open

Open Receive DWA Calculate RTT Open

Open Receive DRI Cleanup Closed

Open Transport level failure Cleanup Closed

Closed Diameter server discovery will make it possible
for simpler Entity shutdown or Close Initial
close connection with peer connection

The Initial and more robust deployment of AAA services. In order Idle states MAY be merged if the local SCTP
implementation is able to
promote interoperable implementations implement the piggyback of Diameter server discovery, data during the following mechanisms are described. These are based on existing
IETF standards.

There are two cases where Diameter server discovery may be performed.

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The first is when a Diameter client needs to discover a first-hop
Diameter server. The second case

connection phase.

When the Cleanup action is when invoked, the failover procedures are
executed (see Section 7.3 for more information).

9.0 Per-Hop Error Signaling

There are many instances where error conditions occur on a Diameter server
node, that needs to
discover another server - for further handling be signalled to the downstream server, and not
necessarily to the Diameter client. Examples of such error conditions
are invalid time synchronization, inability to forward a Diameter
operation. message to a
particular domain, etc. In both these cases, returning the error back to
the following 'search order' is
recommended:

1. The Diameter implementation consults its list of static
(manual) configured Diameter server locations. These client will be
used if they exist only cause delay, and respond.

2. The Diameter implementation uses SLPv2 [28] to discover
Diameter services. The Diameter service template [32] is
included perhaps confusion in Appendix A. It is recommended that SLPv2 security
be deployed (this requires distributing keys to SLPv2 agents.)
This
roaming networks.

Therefore, when such errors occur, it is discussed further in Appendix A.

SLPv2 will allow Diameter implementations to discover the
location of Diameter servers in the local site, as well as
their characteristics. Diameter servers with specific
capabilities (say support necessary for the Accounting extension) can error to
be
requested, handled by the downstream next hop, and only those will some local action be discovered.

3. The Diameter implementation uses DNS taken
to request rectify the SRV RR [33]
for the '_diameter._sctp' server in a particular domain. The
Diameter implementation has to know in advance which domain problem, such as forwarding to
look for an Diameter server in. This could be deduced, for
example, from the 'realm' in a NAI that an Diameter
implementation needed to perform an Diameter operation on.

Diameter allows AAA peers different next hop.

Request +--------+ Link Broken
+-------------------------->|Diameter|----///----+
| +---------------------| | v
+-----+---+ | DSI | Server | +--------+
|Diameter |<-+ (Unable to protect the integrity and privacy Forward) +--------+ |Diameter|
|Client or| | |
| Server |--+ +--------+ | Server |
+---------+ | Request |Diameter| +--------+
+-------------------->| | ^
| Server |-----------+
+--------+
Figure 1 - Example of communication as well as Per-Hop Error Condition

9.1 Device-Status-Ind

The Device-Status-Ind (DSI), indicated by the Command-Code set to perform end-point
authentication. Still, it
282, is prudent sent to employ DNS Security as inform a precaution when using DNS SRV RRs to look up the location of peer that an event has occurred.

When a Diameter server. [34, 35, 36]

3.0 "User" Sessions

When node issues a user requests access DSI message downstream, the target peer
MUST attempt to rectify the network, problem, or issue a Diameter client issues
an authentication and authorization request to its local server. similar message
downstream. The
request contains a Session-Id AVP, which Device-Status-Ind message MUST NOT be proxied, but
MAY be forwarded, as long as the Origin-FQDN AVP is used in subsequent
messages (e.g. subsequent authorization, accounting, etc) relating replaced to
include the user's session. local node's identity.

Message Format

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<Device-Status-Ind> ::= < Diameter Header: 282 >
{ Origin-FQDN }
{ Origin-Realm }
[ DSI-Event ]
* [ AVP ]
0*1< Integrity-Check-Value >

9.1.1 DSI-Event AVP

The Session-Id Result-Code AVP (AVP Code 297) is a means for the client of type Unsigned32 and
servers to correlate
indicates that an event occurred which requires attention from a
Diameter message with a user session.

When a peer. The DSI-Event contains an IANA-managed 32-bit address
space representing events (see section 15.9). Diameter server authorizes provides four
different classes of event notification, all identified by the
thousands digit:
- 1xxx (Informational Events)
- 3xxx (Redirect Notification)
- 4xxx (Transient Failure Events)
- 5xxx (Permanent Failure Events)

A non-recognize class (one whose first digit is not defined in this
section) MUST be handled as a user to use network resources, it
SHOULD add permanent failure.

9.1.1.1 Informational Events

Events that fall within the Authorization-Lifetime AVP Informational category are used to the response. The
Authorization-Lifetime AVP defines the maximum amount of time inform
a peer that a user

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MAY make use of the resources before another authorization request is
to cannot be transmitted to immediately satisfied, and a further
response will be issued in the server. If near future.

DIAMETER_STILL_WORKING 1001
A request's Max-Wait-Time has expired, and the server does not receive
another authorization request before is still
being serviced. This event MAY be sent prior to the timeout occurs, it SHOULD
release any state information related Max-Wait-
Time expiration, to inform the user's session. Note peer that the Authorization-Lifetime AVP implies how long the Diameter
server request is willing not
expected to pay for be serviced in the services rendered, therefore a
Diameter client SHOULD NOT expect payment for services rendered past alloted time, but the session expiration time.

The base protocol does not include any authorization request
messages, since these are largely application-specific and are
defined in a Diameter protocol extension document. However, the base
protocol does define a set of messages is
not being abandoned.

9.1.1.2 Redirect Event

Errors that fall within the Redirect Notification category are used
to terminate
user sessions. These are used to allow servers that maintain state
information to free resources.

3.1 State Machine

This section contains inform a finite state machine, representing peer that the life
cycle of Diameter sessions, request cannot be satisfied locally and MUST
should instead be observed by all Diameter
implementations. The term Service-Specific below refers forwarded to a message
defined in a Diameter extension (e.g. Mobile IP, NASREQ).

State Event Action New State
----- ----- ------ ---------
Idle Client another server.

DIAMETER_REDIRECT_INDICATION 3001
A proxy or Device Requests send serv. Pending
access specific
auth req

Idle Service-Specific authorization send serv. Open redirect server has determined that the request received,
could not be satisfied locally and specific
successfully processed response

Pending Successful Service-Specific Grant Open
Authorization response Access
received

Open Authorization-Lifetime expires send serv. Open
specific
auth req

Open Successful Service-Specific Extend Open
Authorization response Access
received

Open Failed Service-Specific Discon. Closed
Authorization response user/device the initiator of the request

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received.

Open Session-Timeout Expires on send STR Discon
NAS

Open STI Received send STR Discon

Open Session-Timeout Expires on send STI Discon
home AAA server

Discon STI Received ignore Discon

Discon STR Received Discon. Closed
user/device

Discon STA Received Discon. Closed
user/device

Closed Transition

should direct the request directly to state Cleanup

When the Cleanup action is invoked, server, whose contact
information has been added to the Diameter node response.

9.1.1.3 Transient Failure Events

Errors that fall within the transient failures category are used to
inform a peer that the request could not be satisfied at the time it
was received, but MAY attempt be able to
release all resources satisfy the request is the error is
corrected.

DIAMETER_TIME_INVALID 4001
The originator of the Device-Status-Ind message detected a time
synchronization error, and a request for time synchronization
is being requested.

DIAMETER_UNSUPPORTED_TRANSFORM 4002
A message was received that included an Integrity-Check-Value
or CMS-Data AVP [11] that made use of an unsupported transform.

DIAMETER_INVALID_ICV 4003
The Request did not contain a valid Integrity-Check-Value AVP.

9.1.1.4 Permanent Failure Events

Errors that fall within the permanent failures category are used to
inform the peer that the particular session. Any event not
listed above MUST be considered as an error condition, request failed, and a
response, if applicable, MUST cannot be returned to satified by
the originator of the
message.

3.2 Session-Id AVP Device-Status-Ind. The Session-Id AVP (AVP Code 263) is receiver of type OctetString and is used
to identify a specific session (see section 3.0). The Session-Id data
uses DSI
message with the UTF-8 [24] character set. All messages pertaining DSI-Event set to a
specific session MUST include only value that falls within this
event class SHOULD forward the message to an alternate peer, if one Session-Id
is available.

DIAMETER_INVALID_RECORD_ROUTE 5001
The last Record-Route AVP and in the same
value MUST be used throughout message is not set to the life
identity of a session. When present, the Session-Id SHOULD appear immediately following sender of the Diameter
Header (see section 2.1).

For messages message. See Section 12.0 for
more information.

DIAMETER_COMMAND_UNSUPPORTED 5002
The Request contained a Command-Code that do the receiver did not pertain to a specific session, multiple
Session-Id AVPs MAY be present as long as they are encapsulated
within
recognize or support. The Device-Status-Ind message MUST also
contain an Failed-Command-Code AVP of type Grouped. containing the unrecognized
Command-Code.

DIAMETER_UNABLE_TO_DELIVER 5003
The Session-Id MUST request could not be globally unique delivered to a host that handles the
realm, and extension, requested at any given time this time.

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DIAMETER_REALM_NOT_SERVED 5004
The originator of the DSI message could not deliver the message
since it the realm requested is unknown.

DIAMETER_ERROR_TOO_BUSY 5005
When returned, a Diameter node SHOULD attempt to sent the
message to an alternate peer.

DIAMETER_CANNOT_PROCESS_IN_TIME 5006
The time limit in a request's Max-Wait-Time AVP has expired,
and no response is available. This value MAY also be used by to
inform a peer that the server request is not expected to identify be processed
within the session (or flow). The format Max-Wait-Time value.

10.0 End-to-End Error Signaling

There are five different types of
the session identifier SHOULD be as follows:

<Sender's Host-Name><sender's port number> <monotonically increasing
32 bit value><optional value>

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within Diameter.

The monotonically increasing 32 bit value SHOULD NOT start at zero
upon reboot, but rather start at first occurs when a random value. Diameter message is poorly formatted, and
unrecognizable, indicated in the figure below as "Bad Message". This will minimize
error condition applies if a received message is less than the possibility length
of overlapping Session-Ids after the Diameter header. Messages that generate such an error are
ignored.

A second case occurs when a reboot.
Alternatively, Command-Code field is set to an implementation MAY keep track of the increasing
value in non-volatile memory. The optional value
unsupported value, which is implementation
specific but may include a modem's device Id, shown as "Unknown Command" in the figure.
Such errors generate a layer 2 address,
timestamp, etc.

The session Id Device-Status-Ind message, and require per-hop
behavior.

A third case occurs when an AVP is created received, marked as Mandatory ('M'
bit is set), and is unknown by the Diameter device initiating the
session, which in most cases receiver. This error condition is done by
labelled as "Unknown AVP" in the client. Note figure below, and causes a Message-
Reject-Ind message to be sent.

The fourth case occurs when a message is received that contains an
AVP with either an unknown or illegal value. This is labelled as "Bad
AVP Value", and requires that a
Session-Id MAY Message-Reject-Ind message be used by more than one extension (e.g.
authentication for sent.

The last two cases require that a specific service and accounting, Message-Reject-Ind message be
generated to ensure that such errors are identified in both of which
have separate extensions).

3.3 Authorization-Lifetime AVP request
and response messages.

The Authorization-Lifetime AVP (AVP Code 291) last error condition occurs when an extension specific error is
identified in a request or response message. In a message of type Unsigned32
and contains
request or query, the maximum number of seconds of service to natural corresponding answer or response
message MUST be provided used. However, if an error occurs while processing an

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indication, answer or response message, a Message-Reject-Ind is used
to inform the user before peer that an error occurred while processing the user
message.

Error Type Ignore Send Send Send
Message MRI DSI Response
Bad Message X
Unknown Command X
Unknown AVP X
Bad AVP Value X
Request,Query Error X
Answer,Response,Ind Error X

"Ignore Message" indicates that the message is simply dropped. "Send
MRI" means that a Message-Reject-Ind message is sent to be re-authenticated and/or re-
authorized. Great care should be taken when report the Authorization-
Lifetime value
error condition, while "Send DSI" requires that a Device-Status-Ind
message is determined, since sent (see Section 9.1). "Send Response" means that the
response message for a low value could create
significant Diameter traffic, which could congest both request or query message is returned.

10.1 Message-Reject-Ind (MRI) Command

The Message-Reject-Ind (MRI), indicated by the network Command-Code set to
259, provides a generic means of completing transactions by
indicating errors in the messages that initiated them. The Message-
Reject-Ind command is sent in response:

1. An error is found in a message of type Ind, Answer and the servers.

This Response
2. A Unknown AVP, marked as Mandatory, is received
3. An AVP MAY be provided by was received with an unknown, or illegal, value.

The Message-Reject-Ind message MUST contain the client same Hop-by-Hop
Identifier value in the header as a hint of the maximum
duration message that it is willing to accept. However, caused the server DOES NOT
have to observe error
condition. If the hint, and MAY return a value that is smaller than Session-Id AVP was present in the hint. A value of zero means that no re-authorization is required.

3.4 Session-Timeout original message,
the same AVP

The Session-Timeout MUST be present in the MRI.

Message Format

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<Message-Reject-Ind message> ::= < Diameter Header: 259 >
[ Session-Id ]
{ Result-Code }
{ Origin-FQDN }
{ Origin-Realm }
{ Error-Reporting-FQDN }
[ Failed-Command-Code ]
[ Failed-AVP ]
* [ AVP (AVP Code 27) [1] is of type Unsigned32 and
contains ]
* [ Proxy-State ]
* [ Route-Record ]
* [ Destination-Realm ]
0*1< Integrity-Check-Value >

where the maximum number of seconds of service to be provided to Result-Code AVP indicate the user before termination nature of the session. A value of zero means
that this session has an unlimited number of seconds before
termination.

This error causing
rejection, and the Failed-AVP AVP MAY be provided provides some minimal debugging
data by the client as indicating a hint of specific AVP type which caused the maximum
duration that it is willing to accept. However, problem.
See the server DOES NOT
have to observe description of the hint, and MAY return a value that is smaller than Result-Code AVP for indication of when
the hint.

3.5 User-Name Failed-AVP AVP MUST be present in the message. See [25] for
more information.

10.1.1 Failed-AVP AVP

The User-Name Failed-AVP AVP (AVP Code 1) [1] 279) is of type OctetString, which

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contains the User-Name. The value is represented as a UTF-8
character encoded string in a format consistent with the NAI
specification [8].

3.6 Session Termination

The Diameter Base Protocol OctetString and provides
debugging information in cases where a set of messages that MAY be
used by any peer to explicitly request that a previously
authenticated and/or authorized session be terminated. Since the
Session-Id is typically tied rejected or not
fully processed due to erroneous information in a particular service (i.e. Mobile IP,
NASREQ, etc), the session termination messages are used to request
that specific AVP. The
value of the service tied to Result-Code AVP will provide information on the Session Id be terminated.

3.6.1 Session-Termination-Ind

The Session-Termination-Ind (STI), indicated by reason
for the Command-Code set
to 274, MAY be sent by any Failed-AVP AVP.

A Diameter entity to the access device to
request that a particular session be terminated. This message MAY be
used when contain one or more Failed-AVP AVPs, each
containing a server detects complete AVP that a session MUST could not be terminated, which
is typically done as processed successfully.
The possible reasons for this AVP are the presence of an improperly
constructed AVP, an unsupported or unrecognized AVP, an invalid AVP
value; or the omission of a policy decision (e.g. local resources have
been expended, etc). required AVP.

10.1.2 Failed-Command-Code

The Destination-NAI Failed-Command-Code AVP MUST be present, and
contain the NAI (AVP Code 270) is of type Unsigned32 and
contains the access device offending Command-Code that initiated the session (see
section 3.0).

Upon receipt of the STI message, resulted in sending the access device SHOULD issue a
Session-Terminate-Request
Message-Reject-Ind message.

Message Format

<Session-Termination-Ind> ::= < Diameter Header: 274 >
< Session-Id >
{ Host-Name }
{ User-Name }
{ Destination-NAI }
* [

10.2 Result-Code AVP ]
* [ Proxy-State ]
* [ Route-Record ]
* [ Routing-Realm ]
0*1< Integrity-Check-Value >

3.6.2 Session-Termination-Request

The Session-Termination-Request (STR), indicated by the Command-Code
set to 275, is sent by the access device to inform the Diameter
Server that an authenticated and/or authorized session Result-Code AVP (AVP Code 268) is being
terminated. of type Unsigned32 and
indicates whether a particular request was completed successfully or

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Upon receipt of the STR, the

whether an error occurred. All Diameter Server SHOULD release all
resources for the session indicated by messages of type *-Response
or *-Answer MUST include one Result-Code AVP, while messages of type
-Ind MAY include the Session-Id Result-Code AVP. Any
intermediate server in the Proxy-Chain MAY also release any
resources, if necessary.

Message Format

<Session-Termination-Request> ::= < Diameter Header: 275 >
< Session-Id >
{ Host-Name }
{ User-Name }
* [ A non-successful Result-Code
AVP ]
* [ Proxy-State ]
* [ Route-Record ]
* [ Routing-Realm ]
0*1< Integrity-Check-Value >

3.6.3 Session-Termination-Answer (one containing a non 2001 value) MUST include the Error-
Reporting-FQDN AVP.

The Session-Termination-Answer (STA), indicated Result-Code data field contains an IANA-managed 32-bit address
space representing errors (see section 15.4). Diameter provides four
different classes of errors, all identified by the Command-Code
set to 276, thousands digit:
- 1xxx (Informational)
- 2xxx (Success)
- 4xxx (Transient Failures)
- 5xxx (Permanent Failure)

A non-recognize class (one whose first digit is sent by not defined in this
section) MUST be handled as a permanent failure.

10.2.1 Informational

Errors that fall within the Diameter Server Informational category are used to acknowledge inform
a requester that the
session has been terminated. The Result-Code AVP MUST request cannot be present, immediately satisfied and
MAY contain an indication a
further response will be issued in the near future. There are
currently no errors that an error occurred while servicing fall within this class.

10.2.2 Success

Errors that fall within the
STR.

Message Format

<Session-Termination-Answer> ::= < Diameter Header: 276 >
< Session-Id >
{ Result-Code }
{ Host-Name }
{ User-Name }
* [ AVP ]
* [ Proxy-State ]
* [ Route-Record ]
* [ Routing-Realm ]
0*1< Integrity-Check-Value >

4.0 Reliable Transport

In order Success category are used to provide rapid discovery of inform a
peer that a request has been successfully completed.

DIAMETER_SUCCESS 2001
The Request was successfully completed.

10.2.4 Transient Failures

Errors that fall within the failure of transient failures category are used to
inform a communicating
peer, aggressive retransmission and rapid transactions, Diameter
peers MUST peer that the request could not be satisfied at the time it
was received, but MAY be able to send and receive messages over SCTP [26]. A
Diameter peer MAY use TCP [27], as TCP does provide reliable
transport, though it does not have satisfy the request in the future.

DIAMETER_AUTHENTICATION_REJECTED 4001
The authentication process for the user failed, most likely due
to an invalid password used by the user. Further attempts MUST
only be tried after prompting the properties listed above. user for a new password.

DIAMETER_NO_END_2_END_SECURITY 4002
A proxy has detected that end-to-end security has been applied

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5.0 Error Reporting

There are five different types

to portions of errors within Diameter. The first
being where a the Diameter message is poorly formatted message, and
unrecognizable, indicated below by "Bad Message". This error
condition applies if a received message creates a fatal error (e.g.
fails transport level authentication, cannot be parsed, etc).

The second case involves receiving a Command-Code that is the proxy does not
supported, which is shown below by "Unknown Command". The third case
is where an AVP is received, marked mandatory and is unknown by
allow this security mode since it needs to alter the
receiver, which is labeled below as "Unknown AVP".

This fourth case involves receiving a message with a known AVP, yet by
applying some local policies.

10.2.5 Permanent Failures

Errors that fall within the value is either unknown or illegal, which is shown below as "Bad
AVP Value". The last case occurs when an error occurs while
processing a specific extension command, which is not related permanent failures category are used to
inform the
message format and is labeled "Extension Error" below.

Error Type Ignore Message Send Extension
Message-Reject-Ind Response +
Result-Code
Bad Message X
Unknown Command X
Unknown AVP X
Bad AVP Value X
Extension Error X

"Ignore Message" indicates peer that the message request failed, and should not be attempted
again.

DIAMETER_USER_UNKNOWN 5001
A request was received for a user that is simply dropped. unknown, therefore
authentication and/or authorization failed.

DIAMETER_AVP_UNSUPPORTED 5002
The
"Message-Reject-Ind" indicates peer received a message that contained an AVP that a Message-Reject-Ind is not
recognized or supported and was marked with the Mandatory bit.
A Diameter message with this error MUST
be sent to contain one or more
Failed-AVP AVP containing the peer as described in AVPs that caused the appropriate section. failure.

DIAMETER_UNKNOWN_SESSION_ID 5003
The
"Extension Response + Result-Code" error has request or response contained an extension-specific
command code, and indicates that unknown Session-Id.

DIAMETER_AUTHORIZATION_REJECTED 5004
A request was received for which the appropriate Response user could not be
authorized. This error could occur if the service requested is
not permitted to the user.

DIAMETER_INVALID_AVP_VALUE 5005
The request contained an AVP with an invalid value in its data
portion. A Diameter message indicating this error MUST be sent with include
the Result-Code AVP set to offending AVPs within a value Failed-AVP AVP.

DIAMETER_MISSING_AVP 5006
The request did not contain an AVP that
enables is required by the peer to understand
Command Code definition. If this value is sent in the nature of Result-
Code AVP, a Failed-AVP AVP SHOULD be included in the problem.

5.1 Message-Reject-Ind (MRI) Command message.
The Message-Reject-Ind (MRI), indicated by data portion of the Command-Code set to
259, provides a generic means Failed-AVP MUST only contain the AVP
Code of completing transactions by
indicating errors in the messages that initiated them. missing AVP.

DIAMETER_INVALID_CMS_DATA 5007
The Message-
Reject-Ind command is sent in response:

1. An error is found in Request did not contain a message of type Ind, Answer and Response
2. A message that contains an unrecognized command code
3. valid CMS-Data [11] AVP.

DIAMETER_LOOP_DETECTED 5008
A Proxy or Redirect server detected a loop while trying to get
the message was received that cannot pass to the Home Diameter server. Further attempts
should not be attempted until the base protocol error
checking. loop has been fixed.

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In the event that a

DIAMETER_AUTHORIZATION_FAILED 5009
A request is was received that causes an error defined
in a Diameter extension, the appropriate response with for which the Result-
Code AVP SHOULD user could not be sent.

The Message-Reject-Ind message MUST contain the same identification
in the header and include the Session-Id if it was present in the
original message that it is responding to, even if
authorized at this time. This error could occur when the identification user
has already expended allowed resources, or is erroneous.

Message Format only permitted to
access services within a time period.

DIAMETER_CONTRADICTING_AVPS 5010
The structure of the Message-Reject-Ind message is defined as
follows:

<Message-Reject-Ind message> ::= < Home Diameter Header: 259 >
[ Session-Id ]
{ Result-Code }
{ Host-Name }
{ Error-Reporting-NAI }
[ Failed-Command-Code ]
[ Failed-AVP ]
* [ AVP ]
* [ Proxy-State ]
* [ Route-Record ]
* [ Routing-Realm ]
0*1< Integrity-Check-Value >

where the Identifier value server has detected AVPs in the message header request that
contradicted each other, and optionally is not willing to provide service
to the Session-Id AVP are copied from user. One or more Failed-AVP AVPs MUST be present,
containing the message being rejected. AVPs that contradicted each other.

10.3 Error-Message AVP

The
Result-Code Error-Message AVP indicate the nature (AVP Code 281) is of the error causing
rejection, and the Failed-AVP AVP provides some minimal debugging
data by indicating a specific AVP type which caused the problem.
See the description of the OctetString. It is a
human readable UTF-8 character encoded string. It MAY accompany a
Result-Code AVP for indication of when
the Failed-AVP as a human readable error message. The Error-Message
AVP MUST is not intended to be present useful in the message. See [25] for
more information.

5.1.1 Failed-AVP real-time, and SHOULD NOT be
expected to be parsed by network entities.

10.4 Error-Reporting-FQDN AVP

The Failed-AVP Error-Reporting-FQDN AVP (AVP Code 279) 294) is of type OctetString and provides
debugging information OctetString,
encoded in cases where a request is rejected or not
fully processed due the UTF-8 [24] format. This AVP contains the Network
Access Identifier of the Diameter host that set the Result-Code AVP
to erroneous information in a specific AVP. The value of other than 2001 (Success). This AVP is intended to be used
for troubleshooting purposes, and MUST be set when the Result-Code
AVP will provide information on indicates a failure.

11.0 "User" Sessions

When a user requests access to the reason network, a Diameter client issues
an authentication and authorization request to its local server. The
request contains a Session-Id AVP, which is used in subsequent
messages (e.g. subsequent authorization, accounting, etc) relating to
the user's session. The Session-Id AVP is a means for the Failed-AVP AVP.

A client and
servers to correlate a Diameter message MAY contain one or more Failed-AVP AVPs, each
containing with a complete user session.

When a Diameter server authorizes a user to use network resources, it
SHOULD add the Authorization-Lifetime AVP that could not be processed successfully. to the response. The possible reasons for this
Authorization-Lifetime AVP are defines the maximum amount of time a user
MAY make use of the resources before another authorization request is
to be transmitted to the server. If the server does not receive
another authorization request before the timeout occurs, it SHOULD
release any state information related to the presence of an improperly user's session. Note

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constructed AVP, an unsupported or unrecognized AVP, an invalid AVP
value; or the omission of a required AVP.

5.1.2 Failed-Command-Code

The Failed-Command-Code AVP (AVP Code 270) is of type Unsigned32 and
contains the offending Command-Code

that resulted in sending the
Message-Reject-Ind message.

5.2 Result-Code AVP

The Result-Code Authorization-Lifetime AVP (AVP Code 268) is of type Unsigned32 and
indicates whether a particular request was completed successfully or
whether an error occurred. All implies how long the Diameter messages of type *-Response
or *-Answer MUST include one Result-Code AVP, while messages of type
-Ind MAY include
server is willing to pay for the Result-Code AVP. A non-successful Result-Code
AVP (one containing services rendered, therefore a non 2001 value) MUST include the Error-
Reporting-NAI AVP.

The Result Code field contains an IANA-managed 32-bit address space
representing errors (see section 9.4).
Diameter provides five
different classes of errors, all identified by client SHOULD NOT expect payment for services rendered past
the thousands digit:
- 1xxx (Informational)
- 2xxx (Success)
- 3xxx (Redirect Notification)
- 4xxx (Transient Failures)
- 5xxx (Permanent Failure)
- 6xxx (Hop-by-Hop Failure)

A non-recognize class (one whose first digit is session expiration time.

The base protocol does not include any authorization request
messages, since these are largely application-specific and are
defined in this
section) MUST be handled as a permanent failure.

5.2.1 Informational

Errors that fall within Diameter protocol extension document. However, the Informational category base
protocol does define a set of messages that are used to terminate
user sessions. These are used to inform allow servers that maintain state
information to free resources.

11.1 Session State Machine

This section contains a requester that finite state machine, representing the request cannot be immediately satisfied life
cycle of Diameter sessions, and a
further response will MUST be issued in the near future.

DIAMETER_BE_PATIENT 1001 observed by all Diameter
implementations. The term Service-Specific below refers to a message
defined in a Diameter server responsible for authentication and/or
authorizing the user cannot satisfy the extension (e.g. Mobile IP, NASREQ).

State Event Action New State
----- ----- ------ ---------
Idle Client or Device Requests send serv. Pending
access specific
auth req

Idle Service-Specific authorization send serv. Open
request at the moment, received, and will respond within the next 3 seconds.

5.2.2 Success specific
successfully processed response

Pending Successful Service-Specific Grant Open
Authorization response Access
received

Open Authorization-Lifetime expires send serv. Open
specific
auth req

Open Successful Service-Specific Extend Open
Authorization response Access
received

Open Failed Service-Specific Discon. Closed
Authorization response user/device
received.

Open Session-Timeout Expires on send STR Discon
NAS

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Errors that fall within the Success category are used to inform a
peer that a request has been successfully completed.

DIAMETER_SUCCESS March 2001
The Request was successfully completed.

5.2.3 Redirect Notification

Errors that fall within the Redirect Notification category are used

Open STI Received send STR Discon

Open Session-Timeout Expires on send STI Discon
home AAA server

Discon STI Received ignore Discon

Discon STR Received Discon. Closed
user/device

Discon STA Received Discon. Closed
user/device

Closed Transition to inform a peer that state Cleanup

When the request cannot be satisfied locally and
should instead be forwarded Cleanup action is invoked, the Diameter node MAY attempt to another server.

DIAMETER_REDIRECT_INDICATION 3001
A proxy or redirect server has determined that
release all resources for the request
could particular session. Any event not
listed above MUST be satisfied locally considered as an error condition, and the initiator of the request
should direct the request directly a
response, if applicable, MUST be returned to the server, whose contact
information has been added to originator of the response. This error code
MUST NOT be sent in a Message-Reject-Ind
message.

5.2.4 Transient Failures

Errors that fall within the transient failures category are

11.2 Session-Id AVP

The Session-Id AVP (AVP Code 263) is of type OctetString and is used
to
inform identify a peer that the request could not be satisfied at the time it
was received, but MAY be able to satisfy the request in the future.

DIAMETER_AUTHENTICATION_REJECTED 4001 specific session (see section 11.0). The authentication process for Session-Id
data uses the user failed, most likely due UTF-8 [24] character set. All messages pertaining to an invalid password used by the user. Further attempts a
specific session MUST include only one Session-Id AVP and the same
value MUST be tried after prompting used throughout the user for a new password.

DIAMETER_NO_END_2_END_SECURITY 4002
A proxy has detected that end-to-end security has been applied
to portions life of a session. When present,
the Diameter message, and Session-Id SHOULD appear immediately following the proxy does Diameter
Header (see section 3.0).

For messages that do not
allow this security mode pertain to a specific session, multiple
Session-Id AVPs MAY be present as long as they are encapsulated
within an AVP of type Grouped.

The Session-Id MUST be globally unique at any given time since it needs to alter the message is
used by
applying some local policies.

5.2.5 Permanent Failures

Errors that fall within the permanent failures category are used server to
inform identify the peer that session (or flow). The format of
the request failed, and should not session identifier SHOULD be attempted
again.

DIAMETER_USER_UNKNOWN 5001
A request was received for as follows:

<Sender's Origin-FQDN><sender's port number> <monotonically
increasing 32 bit value><optional value>

The monotonically increasing 32 bit value SHOULD NOT start at zero
upon reboot, but rather start at a user that random value. This will minimize
the possibility of overlapping Session-Ids after a reboot.
Alternatively, an implementation MAY keep track of the increasing
value in non-volatile memory. The optional value is unknown, therefore
authentication and/or authorization failed. implementation

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DIAMETER_AVP_UNSUPPORTED 5002
The peer received

specific but may include a message that contained an AVP that modem's device Id, a layer 2 address,
timestamp, etc.

The session Id is not
recognized or supported and was marked with created by the Mandatory bit.
A Diameter message with this error MUST contain one or more
Failed-AVP AVP containing device initiating the AVPs that caused
session, which in most cases is done by the failure.

DIAMETER_UNKNOWN_SESSION_ID 5003
The request or response contained an unknown Session-Id.

DIAMETER_AUTHORIZATION_REJECTED 5004
A request was received client. Note that a
Session-Id MAY be used by more than one extension (e.g.
authentication for a specific service and accounting, both of which
have separate extensions).

11.3 Authorization-Lifetime AVP

The Authorization-Lifetime AVP (AVP Code 291) is of type Unsigned32
and contains the maximum number of seconds of service to be provided
to the user could not be
authorized. This error could occur if before the service requested user is
not permitted to be re-authenticated and/or re-
authorized. Great care should be taken when the user.

DIAMETER_INVALID_AVP_VALUE 5005
The request contained an AVP with an invalid Authorization-
Lifetime value in its data
portion. A is determined, since a low value could create
significant Diameter message with this result code MUST include traffic, which could congest both the offending AVPs within a Failed-AVP AVP.

DIAMETER_MISSING_AVP 5006
The request did not contain an network
and the servers.

This AVP MAY be provided by the client as a hint of the maximum
duration that it is required by willing to accept. However, the
Command Code definition. If this server DOES NOT
have to observe the hint, and MAY return a value that is sent in smaller than
the Result-
Code AVP, a Failed-AVP hint. A value of zero means that no re-authorization is required.

11.4 Session-Timeout AVP SHOULD be included in the message.

The data portion of the Failed-AVP MUST have its Session-Timeout AVP (AVP Code set
to the Data field 27) [1] is of type Unsigned32 and
contains the missing AVP.

DIAMETER_INVALID_CMS_DATA 5007
The Request did not contain a valid CMS-Data [11] AVP.

DIAMETER_LOOP_DETECTED 5008
A Proxy or Redirect server detected a loop while trying maximum number of seconds of service to get
the message be provided to
the Home Diameter server. Further attempts
should not be attempted until user before termination of the loop has been fixed.

DIAMETER_AUTHORIZATION_FAILED 5009 session. A request was received for which the user could not be
authorized at value of zero means
that this time. session has an unlimited number of seconds before
termination.

This error could occur when AVP MAY be provided by the user
has already expended allowed resources, or is only permitted to
access services within client as a time period.

DIAMETER_CONTRADICTING_AVPS 5010
The Home Diameter server has detected AVPs in hint of the request maximum
duration that
contradicted each other, and it is not willing to provide service
to accept. However, the user. One or more Failed-AVP AVPs MUST be present,
containing server DOES NOT
have to observe the AVPs hint, and MAY return a value that contradicted each other.

5.2.6 Hop-by-Hop Failures is smaller than
the hint.

11.5 User-Name AVP

The User-Name AVP (AVP Code 1) [1] is of type OctetString, which
contains the User-Name. The value is represented as a UTF-8
character encoded string in a format consistent with the NAI
specification [8].

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Proxies receiving messages with the Result-Code

11.6 Max-Wait-Time AVP set to an error
within the Hop-by-Hop failure category SHOULD attempt to take some
local action to correct the error. If no local action can be taken to
correct the problem, the error MUST be forwarded towards the
originator of the message.

DIAMETER_INVALID_RECORD_ROUTE 6001

The last Record-Route Max-Wait-Time AVP in the message (AVP Code 295) is not set to the
identity of type Unsigned32, and
contains the sender maximum amount of time the message. See Section 6.0 downstream server is willing
to wait for more
information.

DIAMETER_COMMAND_UNSUPPORTED 6002
The Request contained a Command-Code response. A server that determines that it cannot
satisfy a request within the receiver did not
recognize or support. The Message-Reject-Ind message requested time MUST also
contain an Failed-Command-Code AVP containing issue a DSI message
with the unrecognized
Command-Code.

DIAMETER_TIME_INVALID 6003
This Result-Code value is return DSI-Event set to inform DIAMETER_STILL_WORKING or
DIAMETER_CANNOT_PROCESS_IN_TIME.

11.7 Session Termination

The Diameter Base Protocol provides a peer set of messages that the
message received contained an invalid timestamp value (in
Timestamp AVP).

DIAMETER_UNABLE_TO_DELIVER 6004
The request could not MUST be delivered
used by any peer to a host explicitly request that handles a previously
authenticated and/or authorized session be terminated. Since the
realm requested at this time.

DIAMETER_REALM_NOT_SERVED 6005
A proxy or redirect server has determined that it
Session-Id is unable typically tied to
forward a particular service (i.e. Mobile IP,
NASREQ, etc), the session termination messages are used to request or provide redirect information since
that the
realm portion of service tied to the NAI requested is unknown.

DIAMETER_UNSUPPORTED_TRANSFORM 6006
A message was received that included an Integrity-Check-Value
or CMS-Data AVP [11] that made use of an unsupported transform.

DIAMETER_INVALID_ICV 6007 Session Id be terminated.

11.7.1 Session-Termination-Ind

The Request did not contain a valid Integrity-Check-Value AVP.

DIAMETER_ERROR_TOO_BUSY 6008
When returned, a Diameter node SHOULD attempt Session-Termination-Ind (STI), indicated by the Command-Code set
to 274, MAY be sent by any Diameter entity to the
message access device to an alternate peer.

5.3 Error-Message AVP
request that a particular session be terminated. This message MAY be
used when a server detects that a session MUST be terminated, which
is typically done as a policy decision (e.g. local resources have
been expended, etc). The Error-Message Destination-FQDN AVP (AVP Code 281) is MUST be present, and
contain the NAI of type OctetString. It is a
human readable UTF-8 character encoded string. It MAY accompany the access device that initiated the session (see
section 11.0).

Upon receipt of the STI message, the access device SHOULD issue a
Result-Code
Session-Terminate-Request message.

Message Format

<Session-Termination-Ind> ::= < Diameter Header: 274 >
< Session-Id >
{ Origin-FQDN }
{ Origin-Realm }
{ User-Name }
{ Destination-Realm }
{ Destination-FQDN }
* [ AVP as a human readable error message. The Error-Message ]
* [ Proxy-State ]
0*1< Integrity-Check-Value >

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AVP is not intended to be useful in real-time, and SHOULD NOT be
expected

11.7.2 Session-Termination-Request

The Session-Termination-Request (STR), indicated by the Command-Code
set to be parsed 275, is sent by network entities.

5.4 Error-Reporting-NAI AVP

The Error-Reporting-NAI AVP (AVP Code 294) the access device to inform the Diameter
Server that an authenticated and/or authorized session is of type OctetString.
This being
terminated.

Message Format

<Session-Termination-Request> ::= < Diameter Header: 275 >
< Session-Id >
{ Origin-FQDN }
{ Origin-Realm }
{ User-Name }
{ Destination-Realm }
* [ AVP contains ]
* [ Proxy-State ]
* [ Route-Record ]
0*1< Integrity-Check-Value >

11.7.3 Session-Termination-Answer

The Session-Termination-Answer (STA), indicated by the Network Access Identifier of Command-Code
set to 276, is sent by the Diameter host Server to acknowledge that set the
session has been terminated. The Result-Code AVP to a value other than 2001 (Success).
This AVP is intended to MUST be used for troubleshooting purposes, present, and
MAY contain an indication that an error occurred while servicing the
STR.

Upon sending or receipt of the STA, the Diameter Server MUST be set when release
all resources for the session indicated by the Session-Id AVP. Any
intermediate server in the Proxy-Chain MAY also release any
resources, if necessary.

Message Format

<Session-Termination-Answer> ::= < Diameter Header: 276 >
< Session-Id >
{ Result-Code }
{ Origin-FQDN }
{ Origin-Realm }
{ Destination-FQDN }
{ User-Name }
{ Destination-Realm }
* [ AVP indicates a failure.

6.0 ]
* [ Proxy-State ]
* [ Route-Record ]
0*1< Integrity-Check-Value >

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12.0 Message Routing

This section describes the expected behavior of a Diameter server
acting as a proxy or redirect server.

6.1

12.1 Realm-Based Message Routing

Diameter Message request, query and indication message routing is done
through the use of the realm portion of the Network Access Identifier
(NAI), and an associated realm routing table (see section 11.0). 12.1.1).
The NAI has a format of user@realm, and Diameter servers have a list
of locally supported realms, and MAY have a list of externally
supported realms. When a request, query or indication message is
received that includes a realm that is not locally supported, the
message is proxied to the Diameter entity configured in the "route"
table.

There are instances where the User-Name AVP is not present in
authorization requests. This is typically true in networks where a
request is sent to the network before the call was even answered.
However, such requests MAY need to be proxied. In such cases, the
first hop Diameter proxy MAY append the Routing-Realm AVP to the
Diameter message, by using a DNIS or ANI to Routing-Realm association
table, if it is known. If the message is forwarded to a downstream
proxy, the proxy MAY add the missing Routing-Realm AVP (or replace an
existing Routing-Realm AVP), if the realm associated with the DNIS or
ANI is known.

Figure 1 2 depicts an example where DIA1 receives a request to
authenticate user "joe@abc.com". DIA1 looks up "abc.com" in its local
realm route table and determines that the message must be proxied to
DIA2. DIA2 does the same check, and proxies the message to DIA3. DIA3
checks its realm route table, and determines that the realm is
locally supported, and processes the authentication request, and
returns the response. How the response actually makes it back to the

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sender of the original request is described in the next section.

(Request) (Request)
(User-Name=joe@abc.com) (User-Name=joe@abc.com)
+------+ ------> +------+ ------> +------+
| | | | | |
| DIA1 +-------------------+ DIA2 +-------------------+ DIA3 |
| | | | | |
+------+ <------ +------+ <------ +------+
(Response) (Response)
(User-Name=joe@abc.com) (User-Name=joe@abc.com)

mno.net xyz.com abc.com
Figure 1: Realm-Based Routing

6.2 Behavior of Proxy and Redirect Servers

This section describes the behavior of Diameter proxy and redirect
servers in detail. In both cases, determining the next hop for a
Diameter message is done via the Routing-Realm or the User-Name AVP
[1], whose syntax must comply with the Network Access Identifier
(NAI) [12] specification. When present, the Routing-Realm takes
precedence over the User-Name AVP for routing decisions. The
Routing-Realm AVP, or the realm portion of the User-Name AVP is used
to identify the next hop server the message must be forwarded to. next section.

(Origin-FQDN=dia1.mno.net) (Origin-FQDN=dia1.mno.net)
(Origin-Realm=mno.net) (Origin-Realm=mno.net)
(Destination-Realm=abc.com) (Destination-Realm=abc.com)
(Record-Route=dia2.xyz.com)
+------+ ------> +------+ ------> +------+
| | (Request) | | (Request) | |
| DIA1 +-------------------+ DIA2 +-------------------+ DIA3 |
| | | | | |
+------+ <------ +------+ <------ +------+
mno.net (Response) xyz.com (Response) abc.com
(Destination-Realm=mno.net) (Destination-Realm=abc.net)
(Origin-Realm=abc.com) (Origin-Realm=abc.com)
(Destination-FQDN=dia1.mno.net) (Destination-FQDN=dia1.mno.net)
(Record-Route=dia2.xyz.com)
Figure 2: Realm-Based Routing

Note the processing rules contained in this section are intended to
be used as general guidelines to Diameter developers. Certain
implementations MAY use different methods than the ones described
here, and still be in compliance with the protocol specification.

6.2.1 Proxy and Redirect Server handling of requests

Any request received by a Diameter server MUST perform a next hop
lookup. Lookups

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12.1.1 Realm-Based Routing Table

All Realm-Based routing lookups are performed against what is
commonly known as the Domain Routing Table (see section 11.0). 17.0). A
Domain Routing Table Entry contains the following fields:
- Domain Name. The Domain Name is analogous to the realm portion
of the NAI. This is the field that is typically used as a
primary key in the routing table lookups. Note that some
implementations perform their lookups based on longest-match-
from-the-right on the realm rather than requiring an exact
match.
- Extension Id. It is possible for a routing entry to have a
different destination based on the extension identifier of the
message. This field is typically used as a secondary key field

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in routing table lookups.
- Local Action. The Local Action field is used to identify how a
message should be treated. The following actions are supported:
1. LOCAL - Diameter messages that resolve to a routing entry
with the Local Action set to Local can be satisfied
locally, and do not need to be forwarded to another
server.
2. PROXY - All Diameter messages that fall within this
category MUST be forwarded to a next hop server. The local
server MAY apply its local policies to the message by
including new AVPs to the message prior to forwarding.
See section 6.4 12.4 for more information.
3. REDIRECT - Diameter messages that fall within this
category MUST have the identity of the home Diameter
server(s) appended, and returned to the sender of the
message. See section 6.3 12.3 for more information.
- Server Identifier - One or more servers the message is to be
forwarded to. When the Local Action is set to PROXY, this field
contains the identities of the server(s) server(s) the message must be
forwarded to. When the Local Action field is set to REDIRECT,
this field contains the Home Diameter server(s) for the realm.

It is important to note that Diameter servers MUST support at least
one of the PROXY, REDIRECT, or LOCAL modes of operation. Servers do
not need to support all modes of operation in order to conform with
the protocol specification. Servers MUST NOT reorder AVPs with the
same AVP Code.

When a message is being proxied, the servers in a given domain
routing entry MUST have advertised the Extension Identifier (see
section 6.1.3) for the given message, or have advertised the Wildcard
Extension.

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12.2 Proxy and Redirect Server handling of requests

When a message of type request, query or indication is received by a
proxy or redirect server, and it is determined that the request
cannot be locally handled, the next hop for the request is determined
in the following order:
1. If the Destination-FQDN AVP is present, and the message must host specified
in the AVP can be
forwarded to. When directly contacted, the Local Action field message is set forwarded
to REDIRECT,
this field contains the Home Diameter server(s) host (see section 8.1 for more information), or
2. If the realm.

It Destination-Realm AVP is important to note that Diameter servers MUST support at least
one of present, a routing table lookup
is performed using the PROXY, REDIRECT, or LOCAL modes of operation. Servers do domain specific in the AVP.

A message that does not need to support all modes contain any of operation in order to conform with the protocol specification. Servers above AVPs MUST NOT reorder AVPs be
routed. If the message in question cannot be handled locally, a
Message-Reject-Ind is sent with the
same Result-Code AVP Code.

6.3 set to an
appropriate error condition.

12.3 Redirect Server

A Redirect Server is one that provides NAI Realm to Diameter Home
Server address resolution. When a message is received by a peer, the
Routing-Realm or the realm portion of the User-Name AVP
Destination-Realm is extracted from the message, and the realm portion is used to
perform a lookup in the domain routing table. Implementations MAY
also use the Extension Id as a secondary key in the domain routing
table lookup.

Successful routing table lookups will return one or more home
Diameter servers that could satisfy the message. The home servers are
encoded in one or more Redirect-Host-Address AVPs. If Redirect-Host AVPs, and the Redirect-
Host-Port Command-Code field
is set to be included (meaning that the host is not listening
on the standard Diameter port), it MUST be encapsulated within the
Redirect-Host AVP along with its corresponding Redirect-Host-Address
AVP.

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+------------------+
| Diameter |
| Redirect Server |
+------------------+
^ |
Request | | Response DSI +
joe@xyz.com | | Result Code DSI-Event = Redirect +
| | Redirect Redirect-Host AVP(s)
| v
+----------+ Request +----------+
| abc.net |------------->| xyz.net |
| Diameter | | Diameter |
| Server |<-------------| Server |
+----------+ Response +----------+
Figure 2: 3: Diameter Redirect Server

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Lastly, the Result-Code DSI-Event AVP is added with the Data field of the AVP set
to DIAMETER_REDIRECT_INDICATION [1], DIAMETER_REDIRECT_INDICATION, and the message is returned to the
sender of the request. Redirect servers MAY also include the
certificate of the Home server(s). These certificates are
encapsulated in a CMS-Data AVP [11]. When this occurs, the server
forwarding the request directly to the Home Diameter server SHOULD
include its own certificate in the message.

6.3.1

12.3.1 Redirect-Host AVP

The Redirect-Host AVP (AVP Code 292) is of type Grouped and is found
in responses Device-Status-Ind messages that include the Result-Code DSI-Event AVP set to
DIAMETER_REDIRECT_REQUEST. This AVP only needs to be used if the host
the message is to be redirected to is not listening on the standard
Diameter port. Its Data field has the following ABNF grammar:

Redirect-Host = Redirect-Host-Address Redirect-Host-Port
Redirect-Host-Address = ; See Section 6.3.2 12.3.2
Redirect-Host-Port = ; See Section 6.3.3 12.3.3

The Redirect-Host-Address AVP Data field contains the IP Address of
the Diameter host to which the request MUST be redirected. The
Redirect-Host-Port contains the port number to which the request
should be sent. Upon receipt of such a Result Code, event, and this AVP, the
receiving host SHOULD send the request directly to the host
identified by the Redirect-Host-Address AVP.

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+---------------------------------------------------------------+
| AVP Header (AVP Code = 292) |
+---------------------------------------------------------------+
| Redirect-Host-Address AVP |
+---------------------------------------------------------------+
| Redirect-Host-Port AVP |
+---------------------------------------------------------------+

6.3.2

12.3.2 Redirect-Host-Address AVP

The Redirect-Host-Address AVP (AVP Code 278) is of type Address. Its
use is described in Section 6.3.1.

6.3.3 12.3.1.

12.3.3 Redirect-Host-Port AVP

The Redirect-Host-Port AVP (AVP Code 277) is of type Unsigned32. Its
use is described in Section 6.3.1.

6.4 12.3.1.

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12.4 Proxy Server

This section outlines the processing rules for Diameter proxy
servers. A proxy server can either be stateful or stateless. A Proxy
server MAY act in a stateful manner for some requests, and be
stateless for others. There are two types of states that servers MAY
wish to maintain; transaction and session.

Maintaining transaction state implies that a server keeps a copy of a
request, which is then used when the corresponding response is
received. This could be done to apply local policies to the message,
or simply for auditing purposes. Maintaining session state implies
that a server keeps track of all "active" users. An active user is
one that has been authorized for a particular service, and the server
has not received any indication that the user has relinquished
access.

A stateless proxy is one that does not maintain transaction, nor
session state. It frees the messages sent once acknowledgements are
received by the transport layer.

A stateful proxy can be viewed as a Diameter Server upon receiving a
request, and as a Client when forwarding the message. For all intents
and purposes, stateful servers terminate an upstream "session", and
initiates a downstream "session" (see Figure 3), 4), and MAY provide the
following features:
- Protocol translation (e.g. RADIUS <-> Diameter)
- Limiting resources authorized to a particular user

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- Per user or transaction auditing

+--------+ +-----------------+ +--------+
| Client | --------> | Server | Client | -------> | Server |
+--------+ +-----------------+ +--------+
Figure 3 4 - Example of Stateful Proxy

A stateful proxy that maintains transaction state SHOULD release
transaction information after a request's corresponding response has
been forwarded towards the recipient, and has been acknowledged by
the underlying transport.

A stateful proxy that maintains session state SHOULD release the
session state once it is informed that a user and/or device has
relinquished access.

Home servers processing requests that include the Route-Record and/or
the Proxy-State AVPs MUST return these AVPs in the same order same order in the
corresponding response.

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12.4.1 Proxying Requests

In addition to the rules defined in section 12.2, the
corresponding response.

6.4.1 Proxying Requests following
procedures MUST be handled by proxy servers handling messages of type
request, query or indication.

A proxy server MUST check for forwarding loops before proxying a
message of type Request, Query or Indication. Such as message has
been looped if the server finds its own address in a Route-Record
AVP.

A Diameter server that proxies a message or type Request, Query or
Indication MUST append a Route-Record AVP, which includes its
identity. Diameter Servers that receive messages MUST validate the
last Route-Record AVP in the message and ensure that the host
identified in the AVP is the same as the sender of the message.

A Proxy Server MAY also include the Proxy-State AVP in a message of
type Request or Query, which is used to encode local state
information. The Proxy-State AVP is guaranteed to be present in the
corresponding response.

The message is then forwarded to the downstream Diameter server, as
identified in the Domain Routing Table.

Proxy Server MUST save the Hop-by-Hop Identifier in request messages, and update
if the value of the header field is changed, with a locally unique value.
The saved identifier MAY be encoded in the Proxy-State AVP, and will
be required in the processing of the corresponding response.

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6.4.2

12.4.2 Proxying Responses

A proxy server MUST only process messges of type Response or Answer
whose last Route-Record AVP matches one of its addresses. Any
responses that do not conform to this rule MUST be dropped. The last
Route-Record AVP MUST be removed from the message before it is
forwarded to the next hop, which is identified by the second to last
Route-Record AVP.

If the last Proxy-State AVP in the message is targeted to the local
Diameter server, the AVP MUST be removed.

If a proxy server receives a response with a Result-Code AVP
indicating a failure, it MUST NOT modify the contents of the AVP. Any
additional local errors detected SHOULD be logged, but not reflected
in the Result-Code AVP.

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Prior to forwarding the response, proxy servers MUST restore the
original value of the Diameter header's Hop-by-Hop Identifier field.

6.4.3

12.4.3 Route-Record AVP

The Route-Record AVP (AVP Code 282) is of type OctetString, encoded
in the UTF-8 [24] format, and contains the Fully Qualified Domain
Name of the Proxy appending this AVP to a Diameter message.

6.4.4

12.4.4 Proxy-State AVP

The Proxy-State AVP (AVP Code = 33) is of type Grouped. The Grouped
Data field has the following ABNF grammar:

Proxy-State = Proxy-Address Proxy-Info
Proxy-Address = ; See Section 6.4.5 12.4.5
Proxy-Info = ; See Section 6.4.6 12.4.6

The Proxy-Address AVP Data field contains one of the IP addresses of
the system that created the AVP. This assists hosts in determining
whether a Proxy-State AVP is intended for the local host. The Proxy-
Info AVP contains state information, and MUST be treated as opaque
data.

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+---------------------------------------------------------------+
| AVP Header (AVP Code = 33) |
+---------------------------------------------------------------+
| Proxy-Address AVP |
+---------------------------------------------------------------+
| Proxy-Info AVP |
+---------------------------------------------------------------+

6.4.5

12.4.5 Proxy-Address AVP

The Proxy-Address AVP (AVP Code = 280) is of type Address. Its use
is described in Section 6.4.4.

6.4.6 12.4.4.

12.4.6 Proxy-Info AVP

The Proxy-Info AVP (AVP Code = 284) is of type OctetString. Its use
is described in Section 6.4.4.

6.4.7 Routing-Realm 12.4.4.

12.4.7 Destination-Realm AVP

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The Routing-Realm Destination-Realm AVP (AVP Code 283) is of type OctetString OctetString,
encoded in the UTF-8 [24] format, and contains the realm the message
is to be routed to. Diameter Clients insert the realm portion of the Network Access Identifier.
User-Name AVP, while home servers insert the value of the Origin-
Realm AVP into this AVP. When present, the Routing-Realm Destination-Realm AVP MAY be is
used to perform any message routing decisions.

6.5

12.5 Applying Local Policies

Proxies MAY apply local access policies to Diameter requests, or
responses, by adding, changing or deleting AVPs in the messages.
Proxies that apply local policies MUST NOT allow end-to-end security
on any messages that traverse through it, unless security is
terminated locally.

A proxy wishing to modify a Diameter message to enforce some local
policy that detects that end-to-end security has been applied to the
message MUST return a response to the originator with the Result-Code
set to DIAMETER_NO_END_2_END_SECURITY. The originator of the request
MAY re-issue the request with no end-to-end security if it falls
within its local policy.

In the event that the Home Diameter server receives a request with
contradictory information (possibly due to some proxy adding a local
policy), it MAY accept the latest AVP, or MAY return the response
with the Result Code Result-Code AVP set to DIAMETER_CONTRADICTING_AVPS. However,

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a NAS receiving a response that contains contradictory information
SHOULD reject service to the user.

6.6

12.6 Hiding Network Topology

Stateful proxies forwarding requests to servers outside of their
administrative domain MAY hide the internal network topology. Servers
perform this by removing all Route-Record AVPs in the message, and
maintains the Route-Record AVPs to add to the corresponding response.
Such stateful servers MUST still add their own Route-Record AVP to
the request prior to forwarding.

6.7

12.7 Loop Detection

When a Diameter Proxy or Redirect server receives a message of type
Request, Query or Indication, it MUST examine all Route-Record AVPs
in the message to determine whether such an AVP already exists with
the local server's identity. If an AVP with the local host's identity
is found in the request, it is an indication that the message is
being looped through the same set of proxies. When such an event
occurs, the Diameter server that detects the loop returns a response
with the Result-Code AVP set to DIAMETER_LOOP_DETECTED.

6.8 Finding a Target NAS within a Domain

The Diameter protocol supports unsolicited server initiated messages.
However, when such messages are transmitted, they have a specific
target Network Access Server (NAS) in mind. Unsolicited server
initiated messages are unique in that they contain the Destination-
NAI AVP. Routing of such messages follow the same set of guidelines
described in section 6.0, with one exception. When a proxy server has
determined that a message, which includes the Destination-NAI AVP,
has reached its target realm, the Destination-NAI AVP local host's identity
is used to
identify found in the actual NAS request, it is an indication that the message should be forwarded to.

6.8.1 Destination-NAI AVP

The Destination-NAI AVP (AVP Code 293) [1] is of type OctetString,
and contains the NAI [8] of the intended recipient of the message.
This AVP MUST be present in all unsolicited server initiated
messages.

7.0 Diameter Message Security

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being looped through the same set of proxies. When such an event
occurs, the Diameter server that detects the loop returns a response
with the Result-Code AVP set to DIAMETER_LOOP_DETECTED.

13.0 Diameter Message Security

The Diameter Base protocol MAY be secured in one of three ways. The
first method does not involve any security mechanisms in the Diameter
protocol, but relies on an underlying security mechanism, such as IP
Security. The second method is hop-by-hop security, which SHOULD be
supported by all Diameter implementations. The third method is
optional and requires a Public Key Infrastructure [14], and is
documented in [11].

7.1

13.1 Hop-by-Hop Security

Diameter Hop-by-Hop security provides message integrity and per AVP
encryption, and requires that the communicating entities have a pre-
configured shared secret. Hop-by-Hop security is very difficult to
deploy and administer in large scale networks and involves symmetric
trust, unlike security based on a public key infrastructure (PKI).
PKI is used for Diameter End-to-End security, and is defined in [11].
Hop-by-Hop security may be desirable in environments where symmetric
cryptography is sufficient or when a PKI is not available.

Figure 4 5 below provides an example of hop-by-hop security in a proxy
chain. Assuming that the packet was received by DIA2 from DIA1, and
was to be proxied to DIA3, the following steps would be taken:

1. Validating the message's integrity using the shared secret with
DIA1, and removing the authenticated security AVPs.

2. Decrypting any encrypted AVPs using the secret shared with DIA1.

3. Re-encrypting AVPs using the secret shared with DIA3.

4. Computing the message hash using the secret shared with DIA3,
and adding it to the ICV AVP in the Diameter message.

(Shared-Secret-1) (Shared-Secret-2)
+------+ -----> +------+ ------> +------+
| | |1 3| | |
| DIA1 +------------------>+ DIA2 +------------------>+ DIA3 |
| | |2 4| | |
+------+ +------+ +------+
Figure 4: 5: Hop-by-Hop Security in Proxy Environments

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The above steps that each proxy MUST perform in a proxy chain clearly
describes the security issues associated with hop-by-hop security in
a proxy environment. Since the message integrity is re-computed at
each node in the chain, it is not possible to detect if a proxy
modified information in the message (e.g. session time). Furthermore,
any sensitive information would be known to all proxies in the chain,

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since each node must decrypt AVPs. Therefore, Any AVPs that contain
data that MUST NOT be seen by intermediate Diameter nodes MUST be
protected via the mechanism described in the strong security
extension [11].

It is highly recommended that the size of the shared secrets used be
sufficiently long (e.g. 128 bits), and that different shared secrets
be used for both authentication and encryption.

7.1.1

13.1.1 Integrity-Check-Value AVP

The Integrity-Check-Value AVP (AVP Code 259) is of type Grouped and
is used for hop-by-hop message authentication and integrity.

The Diameter header as well as all AVPs (including padding) up to the
Digest AVP is protected by the Integrity-Check-Value AVP. Note that
the Message Length field in the Diameter header MUST be set to zero
(0) prior to the ICV calculation. The Timestamp AVP provides replay
protection and the Nonce AVP provides randomness. If present, any
AVPs in a message that is not succeeded by the Integrity-Check-Value
AVP MUST be ignored.

All Diameter implementations SHOULD support this AVP.

The Integrity-Check-Value AVP (AVP Code = 259) is of type Grouped.
The grammar for the grouped Data field is defined is:

Integrity-Check-Value = Nonce Time Auth-Trans-Id Key-ID Digest
Nonce = ; Nonce, See Section 7.2 13.2
Timestamp = ; Timestamp, See Section 7.3 13.3
Auth-Trans-Id = ; Authentication-Transform-Id, /
; See Section 7.1.1.1 13.1.1.1
Key-ID = ; Key-ID, See Section 7.4 13.4
Digest = ; Digest, See Section 7.1.1.2 13.1.1.2

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+---------------------------------------------------------------+
| AVP Header (AVP Code = 259) |
+---------------------------------------------------------------+
| Nonce AVP |
+---------------------------------------------------------------+
| Timestamp AVP |
+---------------------------------------------------------------+
| Authentication-Transform-Id AVP |
+---------------------------------------------------------------+
| Key-ID AVP |
+---------------------------------------------------------------+
| Digest AVP |
+---------------------------------------------------------------+

7.1.1.1

13.1.1.1 Authentication-Transform-Id AVP

The Transform-Id AVP (AVP Code = 285) is of type Unsigned32. This
value identifies the transform that was used to compute the ICV. The
following values are defined in this document:

HMAC-MD5-96[6] 1
The ICV is computed using the HMAC-MD5 algorithm, and the first
12 bytes of the hash output is included in the Digest AVP. All
Diameter implementations supporting this AVP MUST support this
transform. Using the example code provided in [6], the
following call would be used to generate the Digest AVP:

hmac_md5(DiameterMessage, MessageLength, Secret,
Secretlength, Output)

where the DiameterMessage is the complete message up to the
Digest AVP.

7.1.1.2

13.1.1.2 Digest AVP

The Digest AVP (AVP Code = 287) is of type OctetString. This value
contains the output from the hashing algorithm, covering all AVPs in
the message, including all AVPs in the Integrity-Check-Value AVP up
to, but not including, the Digest AVP.

7.1.2

13.1.2 Encrypted-Payload AVP

The Encrypted-Payload AVP (AVP Code 260) is of type Grouped and is
used to encapsulate encrypted AVPs for privacy during transmission.

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Hop-by-Hop confidentiality is achieved by encapsulating all AVPs
which are to be encrypted into an Encrypted-Payload AVP. This
feature SHOULD be supported by Diameter implementations.

The grammar for the grouped Data field is defined is:

Encrypted-Payload = Enc-Trans-Id Key-ID ptextlen data
Enc-Trans-Id = ; Encryption-Transform-Id, /
; See Section 7.1.2.1 13.1.2.1
Key-ID = ; See Section 7.4 13.4
ptextlen = ; Plaintext-Data-Length, See Section 7.1.2.2 13.1.2.2
data = ; Encrypted-Data, See Section 7.1.2.3 13.1.2.3

+---------------------------------------------------------------+
| AVP Header (AVP Code = 260) |
+---------------------------------------------------------------+
| Encryption-Transform-Id AVP |
+---------------------------------------------------------------+
| Key-ID AVP |
+---------------------------------------------------------------+
| Plaintext-Data-Length AVP |
+---------------------------------------------------------------+
| Encrypted-Data AVP |
+---------------------------------------------------------------+

7.1.2.1

13.1.2.1 Encryption-Transform-Id AVP

The Encryption-Transform-Id AVP (AVP Code = 288) is of type
Unsigned32. This AVP identifies the transform that was used to
encrypt the data contained in the Encrypted-Data AVP. The following
values are defined in this document:

MD5 1
See section 7.1.2.4 13.1.2.1.1 for more information.

7.1.2.1.1

13.1.2.1.1 MD5 Payload Hiding

The plain text (which is a buffer containing one or more AVPs) is
first padded to a sixteen (16) byte boundary with 0 bytes. Since the
encapsulated AVPs have length fields, it is possible to detect their
boundaries, whether or not padding has been done.

One or more Nonce AVPs MUST precede an Encrypted-Payload AVP. An MD5
hash is performed on the:

- last Nonce AVP which precedes the Encrypted-Payload AVP

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- the shared authentication secret

This MD5 hash value is then XORed with the first 16 octet segment of
the buffer to encrypt. The resulting 16 octet result is saved as the
first 16 octets of the encrypted buffer. The result is also used to
calculate a new value using MD5:

- the shared authentication secret
- the 16 byte result of the previous XOR

This value is then XORed with the next 16 bytes. This is done for
each 16 bytes successively in the buffer to encrypt, producing an
equal sized encrypted buffer.

The receiver of a Diameter message with an Encrypted-Payload AVP MUST
first check the integrity of the message, either through the ICV, or
the CMS-Data AVP [11] if it protects the Encrypted-Payload AVP. Then
the Encrypted-Payload AVP is decrypted, by reversing the above
procedure, which applied to the buffer will reproduce the plain text
version. The decapsulated AVPs are then used to process the Diameter
message in the normal manner.

7.1.2.2

13.1.2.2 Plaintext-Data-Length AVP

The Plaintext-Data-Length AVP (AVP Code = 289) is of type Unsigned32,
and contains the length of the plaintext data. This AVP is necessary
in order to not treat any possible padded data, added as part of the
encryption transform, as part of the plaintext.

7.1.2.3

13.1.2.3 Encrypted-Data AVP

The Encrypted-Data AVP (AVP Code = 290) is of type OctetString. This
AVP contains the encrypted AVPs.

7.2

13.2 Nonce AVP

The Nonce AVP (AVP Code 261) is of type OctetString and is present in
the Integrity-Check-Value AVP and is used to ensure randomness within
a message. The content of this AVP MUST be a random value of at least
128 bits.

7.3

13.3 Timestamp AVP

The Timestamp AVP (AVP Code 262) is of type Unsigned32 and is used to

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add replay protection to the Diameter protocol. The Data field of
this AVP is the most significant four octets returned from an NTP
[18] server that indicates the number of seconds expired since Jan.
1, 1900.

Messages that are older than a configurable maximum age SHOULD be
rejected (see section 11.0) 17.0) and a response SHOULD be returned with
the Result-Code AVP Data field set to DIAMETER_TIMEOUT. Note that the
larger the configurable value, the more susceptible one is to a
replay attack. However, one does have to take into account the
possibility for clock drift, and the latency involved in the
transmission of the message over the network. The timestamp AVP
SHOULD be updated prior to retransmission.

A Diameter node that receives a message with the Result-Code AVP set
to Diameter-TIMEOUT DIAMETER-TIMEOUT MAY use the time found in the Timestamp AVP
within the reply in order to synchronize its clock with its peer.
When time synchronization is done, the sender MUST NOT change its
local time, but SHOULD adjust the time delta for all outgoing
messages to the peer, and require that its local time be used in
received messages.

Implementations must be prepared to wrap at the epochal 2038 where
Time values are used, and 0,1,... MUST be considered greater than
2^32-1 at that time.

7.4

13.4 Key-Id AVP

The Key-Id AVP (AVP Code = 286) is of type Unsigned32. This value
contains a key identifier, which is used to identify the keying
information used to generate the Digest AVP or the Encrypted-Data
AVP.

8.0

14.0 AVP Table

The following table presents the AVPs defined in this document, and
specifies in which Diameter messages they MAY, or MAY NOT be present.
Note that AVPs that can only be present within a Grouped AVP are not
represented in this table.

The table uses the following symbols:
0 The AVP MUST NOT be present in the message.
0+ Zero or more instances of the AVP MAY be present in the
message.
0-1 Zero or one instance of the AVP MAY be present in the
message.

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1 One instance of the AVP MUST be present in the message.

+-----------------------------+
| Command-Code |
|-----+-----+-----+-----+-----+
Attribute Name | DRI | MRI | STI | STR | STA |
------------------------------|-----+-----+-----+-----+-----|
Authorization-Lifetime | 0 | 0 | 0 | 0 | 0 |
Destination-NAI | 0 | 0 | 1 | 0 | 0 |
Encrypted-Payload | 0 | 0 | 0 | 0 | 0 |
Error-Message | 0 | 0 | 0 | 0 | 0 |
Error-Reporting-NAI | 0 | 1 | 0 | 0 | 0 |
Extension-Id | 1+ | 0 | 0 | 0 | 0 |
Failed-AVP | 0 | 0-1 AVP MUST be present in the message.

+-------------------------------+
| 0 Command-Code | 0
|---+---+---+---+---+---+---+---+
Attribute Name |DRI|DSI|DWR|DWA|MRI|STI|STR|STA|
------------------------------|---+---+---+---+---+---+---+---|
Authorization-Lifetime |0 |0 |0 |0 |0 |0 |0 |0 |
Destination-FQDN |0 |0 |0 |1 |0+ |1 |0+ |1 | 0
Destination-Realm |1 |1 |1 |1 |1 |1 |1 |1 |
Failed-Command-Code
DSI-Event |0 |1 |0 |0 |0 |0 |0 |0 | 0
Encrypted-Payload |0 |0 |0 |0 |0 |0 |0 |0 | 0-1
Error-Message |0 |0 |0 |0 |0 |0 |0 |0 |
Error-Reporting-FQDN |0 |0 |0 |0 |1 |0 |0 |0 | 0
Extension-Id |1+ |0 |0 |0 |0 |0 |0 |0 | 0
Failed-AVP |0 |0 |0 |0 |0-1|0 |0 |0 | 0
Failed-Command-Code |0 |0 |0 |0 |0-1|0 |0 |0 |
Firmware-Revision | 0-1 | 0 | 0 | 0 | 0 |0-1|0 |0 |0 |0 |0 |0 |0 |
Host-IP-Address | 1+ | 0 | 0 | 0 | 0 |
Host-Name | 1 | 1 | 1 | 1 | 1 |1+ |0 |0 |0 |0 |0 |0 |0 |
Integrity-Check-Value |0-1|0-1|0-1|0-1|0-1|0-1|0-1|0-1|
Max-Time-Wait |0 |0 |0 |0 |0 |0 |0 |0 | 0-1 | 0-1 | 0-1 | 0-1
Origin-FQDN |1 |1 |1 |1 |1 |1 |1 |1 | 0-1
Origin-Realm |1 |1 |1 |1 |1 |1 |1 |1 |
Proxy-State | 0 | 0+ | 0+ | 0+ | 0+ |0 |0 |0 |0 |0+ |0+ |0+ |0+ |
Redirect-Host | 0 | 0 | 0 | 0 | 0 |0 |0 |0 |0 |0 |0 |0 |0 |
Result-Code | 0 | 1 | 0 | 0 | 1 |0 |0 |0 |1 |1 |0 |0 |1 |
Route-Record | 0 | 0+ | 0+ | 0+ | 0+ |
Routing-Realm | 0 | 0+ | 0+ | 0+ | 0+ |0 |0 |0 |0 |0+ |0+ |0+ |0+ |
Session-Id | 0 | 0-1 | 1 | 1 | 1 |0 |0 |0 |0 |0-1|1 |1 |1 |
Session-Timeout | 0 | 0 | 0 | 0 | 0 |0 |0 |0 |0 |0 |0 |0 |0 |
Timestamp | 0 | 0 | 0 | 0 | 0 |0 |0 |0 |0 |0 |0 |0 |0 |
User-Name | 0 | 0 | 1 | 1 | 1 |0 |0 |0 |0 |0 |1 |1 |1 |
Vendor-Id |1 |0 |0 |0 |0 |0 |0 |0 | 1 | 0 | 0 | 0 | 0 |
------------------------------|-----+-----+-----+-----+-----|

9.0
------------------------------|---+---+---+---+---+---+---+---|

15.0 IANA Considerations

This document defines a number of assigned numbers to be maintained
by the IANA. This section explains the criteria to be used by the
IANA to assign additional numbers in each of these lists. The
following subsections describe the assignment policy for the
namespaces defined elsewhere in this document.

9.1

15.1 AVP Attributes

As defined in section 2.3, 4.0, AVPs contain vendor ID, attribute and Data
fields. For vendor ID value of 0, IANA will maintain a registry of

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assigned AVP codes and in some case also values. Attribute 0-254 are
assigned from the RADIUS protocol [1], whose attributes are also
maintained through IANA. AVP Codes 256-280 are assigned within this

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document. The remaining values are available for assignment through
Designated Expert [12].

9.2

15.2 Command Code Values

As defined in section 2.1, 3.0, the Command Code field has an associated
value maintained by IANA. Values 0-255 are reserved for backward
RADIUS compatibility, and values 257, 259, 274, 275 and 276 are
defined in this specification. The remaining values are available for
assignment via Designated Expert [12].

9.3

15.3 Extension Identifier Values

As defined in section 2.6.5, 6.1.3, the Extension Identifier is used to
identify a specific Diameter Extension. All values, other than zero
(0) are available for assignment via Standards Action [12].

Note that the Diameter protocol is not inteded to be extended for any
purpose. Any extensions added to the protocol MUST ensure that they
fit within the existing framework, and that no changes to the base
protocol are required.

9.4

15.4 Result-Code AVP Values

As defined in Section 5.2, 10.2, the Result Code Result-Code AVP (AVP Code 268)
defines the values 1001, 2001, 3001, 4001-4002, 5001-5010 4001-4002 and 6001-6008. 5001-5010. All remaining
values are available for assignment via IETF Consensus [12].

9.5

15.5 Authentication-Transform-Id AVP Values

Section 7.1.1.1 13.1.1.1 defines the Authentication-Transform-Id AVP (AVP
Code 285) which is used to identify the authentication algorithm used
to generate the contents of the Digest AVP. This document reserves
the value 1. All remaining values are available for assignment via
Designated Expert [12].

9.6

15.6 Encryption-Transform-Id AVP Values

Section 7.1.2.1 13.1.2.1 defines the Encryption-Transform-Id AVP (AVP Code
288) which is used to identify the encryption algorithm used to

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generate the contents of the Encrypted-Data AVP. This document
reserves the value 1. All remaining values are available for

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assignment via Designated Expert [12].

9.7

15.7 Message Header Bits

There are thirteen bits in the Flags field of the Diameter header.
This document assigns bit 1 ('R'esponse), bit 2 ('I'nterrogation) and
bit 3 ('E'xpected Reply). Bits 4 through 13 should only be assigned
via a Standards Action [12].

9.8

15.8 AVP Header Bits

There are 16 bits in the Flags field of the AVP Header. Header, defined in
section 4.0. This document assigns bit 1 ('M'andatory), bit 3
('V'endor Specific) and bit 5 ('P'rotected). The remaining bits
should only be assigned via a Standards Action [12].

10.0

15.9 DSI-Event AVP Values

As defined in Section 9.1.1, the DSI-Event AVP (AVP Code 297) defines
the values 1001, 3001, 4001-4003 and 5001-5006. All remaining values
are available for assignment via IETF Consensus [12].

16.0 Open Issues

The following are the open issues that SHOULD be addressed in future
versions of the Diameter protocol:

- AVPs with time values are represented by Unsigned32 type data.
This value is a timestamp consistent with NTP [18]. This field
is expected to expire sometime in 2038. Future investigation
SHOULD be done to determine if a 64 bit time format could be
used.

- The fact that the Sender's IP Address is used in the
construction of the Session-Id means that the introduction of
Network Address Translation MAY cause two hosts to represent the
same Session Identifier. This area needs to be investigated
further to be able to support Diameter hosts on a private
network.

11.0

17.0 Diameter protocol related configurable parameters

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This section contains the configurable parameters that are found
throughout this document:

Diameter Peer
A Diameter entity MAY communicate with peers that are
statically configured. A statically configured Diameter peer
would require that either the IP address or the fully qualified
domain name (FQDN) be supplied, which would then be used to

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resolve through DNS.

Realm Routing Table
A Diameter Proxy server routes messages based on the realm
portion of a Network Access Identifier (NAI). The server MUST
have a table of Realms Names, and the address of the peer to
which the message must be forwarded to. The routing table MAY
also include a "default route", which is typically used for all
messages that cannot be locally processed.

Maximum Age of an outstanding message
Messages older than the maximum age SHOULD be rejected, as
described in section 7.3. 13.3. The recommended value is 4 seconds.

RTT-Multiplier
The Round Trip Time Multiplier is used to determine when a DWR
message is to be sent to an inactive peer. The recommended
valus is 4.

Shared Secret
The shared secret is a value that is known by two communicating
peers, and is used to generate the Integrity-Check-Value and
the Encryption-Payload AVP. There is no default.

11.0

Watchdog Interval Period
The Watchdog Interval Period is the frequency at which DWR
messages are sent to inactive peers. The recommended value is
30 seconds.

18.0 Security Considerations

The Diameter base protocol requires that two communicating peers
exchange messages in a secure fashion. This document describes two
security methods that can be used. The first requires no security at
the application layer, but rather relies on an underlying security
mechanism, such as IP Security.

When IP Security is not available, or desirable, the Diameter
protocol MAY use hop-by-hop security, which requires communicating

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peers to negotiate a symmetric key through some out of band
mechanism. Hop-by-Hop security provides replay protection by
requiring that the communicating peers share a time source, such as
an NTP server. Information of a sensitive nature, which MUST NOT be
seen by any intermediate Diameter node MUST NOT be encrypted using
hop-by-hop encryption.

When the Diameter protocol is used in an inter-domain network, strong
application level security MAY be required, such as non-repudiation.
When the communicating peers do require this level of security either
for legal or business purposes, the extension defined in [11] MAY be
used. This security model provides AVP-level authentication, and the
encryption mechanism is designed such that only the target host has
the keying information required to decrypt the information.

12.0

19.0 References

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[1] Rigney, et alia, "RADIUS", RFC-2138, April 1997 1997.

[2] Reynolds, Postel, "Assigned Numbers", RFC 1700, October 1994.

[3] Postel, "User Datagram Protocol", RFC 768, August 1980.

[4] Rivest, "The MD5 Message-Digest Algorithm", RFC 1321, April
1992.

[5] Kaufman, Perlman, Speciner, "Network Security: Private Communi-
cations in a Public World", Prentice Hall, March 1995, ISBN 0-
13-061466-1.

[6] Krawczyk, Bellare, Canetti, "HMAC: Keyed-Hashing for Message
Authentication", RFC 2104, January 1997.

[7] P. Calhoun, W. Bulley, A. Rubens, J. Haag, "Diameter NASREQ
Extension", draft-ietf-aaa-diameter-nasreq-00.txt, draft-ietf-aaa-diameter-nasreq-01.txt, IETF work in
progress, February March 2001.

[8] Aboba, Beadles "The Network Access Identifier." RFC 2486. Janu-
ary 1999.

[9] Calhoun, Zorn, Pan, Akhtar, "Diameter Framework", draft-ietf-
aaa-diameter-framework-00.txt,
aaa-diameter-framework-01.txt, IETF work in progress, February March
2001.

[10] P. Calhoun, C. Perkins, "Diameter Mobile IP Extensions", draft-
ietf-aaa-diameter-mobileip-00.txt,
ietf-aaa-diameter-mobileip-01.txt, IETF work in progress, Febru-
ary March

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2001.

[11] P. Calhoun, W. Bulley, S. Farrell, "Diameter Strong Security
Extension", draft-calhoun-diameter-strong-crypto-06.txt (work in
progress), February 2001.

[12] Narten, Alvestrand,"Guidelines for Writing an IANA Considera-
tions Section in RFCs", BCP 26, RFC 2434, October 1998

[13] S. Bradner, "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.

[14] Myers, Ankney, Malpani, Galperin, Adams, "X.509 Internet Public
Key Infrastructure Online Certificate Status Protocol (OCSP)",
RFC 2560, June 1999.

[15] Arkko, Calhoun, Patel, Zorn, "Diameter Accounting Extension",
draft-ietf-aaa-diameter-accounting-00.txt,
draft-ietf-aaa-diameter-accounting-01.txt, IETF work in pro-
gress, February March 2001.

Calhoun et al. expires July 2001 [Page 52]

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[16] Hinden, Deering, "IP Version 6 Addressing Architecture", RFC
2373, July 1998.

[17] ISI, "Internet Protocol", RFC 791, September 1981.

[18] Mills, "Simple Network Time Protocol (SNTP) Version 4 for IPv4,
IPv6 and OSI, RFC 2030, October 1996.

[19] Housley, Ford, Polk, Solo, "Internet X.509 Public Key Infras-
tructure Certificate and CRL Profile", RFC 2459, January 1999.

[20] B. Aboba, G. Zorn, "Criteria for Evaluating Roaming Protocols",
RFC 2477, January 1999.

[21] M. Beadles, D. Mitton, "Criteria for Evaluating Network Access
Server Protocols", draft-ietf-nasreq-criteria-05.txt, IETF work
in progress, June 2000.

[22] T. Hiller and al, "CDMA2000 Wireless Data Requirements for AAA",
draft-hiller-cdma2000-aaa-02.txt, IETF work in progress, Sep-
tember 2000.

[23] S. Glass, S. Jacobs, C. Perkins, "Mobile IP Authentication,
Authorization, and Accounting Requirements". RFC 2977. October
2000.

[24] F. Yergeau, "UTF-8, a transformation format of ISO 10646", RFC
2279, January 1998.

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[25] P. Calhoun, A. Rubens, H. Akhtar, E. Guttman, W. Bulley, J.
Haag, "Diameter Implementation Guidelines", draft-ietf-aaa-
diameter-impl-guide-00.txt, IETF work in progress, June 2000.

[26] R. Stewart et al., "Stream Control Transmission Protocol". RFC
2960. October 2000.

[27] Postel, J. "Transmission Control Protocol", RFC 793, January
1981.

[28] E. Guttman, C. Perkins, J. Veizades, M. Day. "Service Location
Protocol, Version 2", RFC 2165, June 1999.

[29] P. Calhoun, "Diameter Resource Management", draft-calhoun-
diameter-res-mgmt-06.txt, IETF Work in Progress, February 2001.

[30] Institute of Electrical and Electronics Engineers, "IEEE Stan-
dard for Binary Floating-Point Arithmetic", ANSI/IEEE Standard
754-1985, August 1985.

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[31] D. Crocker, P. Overell, "Augmented BNF for Syntax Specifica-
tions: ABNF", RFC 2234, November 1997.

[32] E. Guttman, C. Perkins, J. Kempf, "Service Templates and Ser-
vice: Schemes", RFC 2609, June 1999.

[33] A. Gulbrandsen, P. Vixie, L. Esibov, "A DNS RR for specifying
the location of services (DNS SRV)", RFC 2782, February 2000.

[34] D. Eastlake, "Domain Name System Security Extensions", RFC 2535,
March 1999.

[35] D. Eastlake, "DNS Security Operational Considerations", RFC
2541, March 1999.

[36] D. Eastlake, "DNS Request and Transaction Signatures ( SIG(0)s
)", RFC 2931, September 2000.

13.0

[37] S. Kent, R. Atkinson, "Security Architecture for the Internet
Protocol", RFC 2401, November 1998.

[38] A. Frier, P. Karlton, and P. Kocher, "The SSL 3.0 Protocol",
Netscape Communications Corp., Nov 18, 1996.

[39] "The Communications of the ACM" Vol.33, No.6 (June 1990), pp.
677-680.

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20.0 Acknowledgements

The authors would like to thank Nenad Trifunovic, Tony Johansson and
Pankaj Patel for their participation in the Document Reading Party.
Allison Mankin's assistance was invaluable in working out transport
issues, and similarly with Steven Bellovin's help in the security
area.

The authors would also like to acknowledge the following people for
their contribution in the development of the Diameter protocol:

Bernard Aboba, Jari Arkko, William Bulley, Daniel C. Fox, Lol Grant,
Ignacio Goyret, Nancy Greene, Peter Heitman, Paul Krumviede, Fergal
Ladley, Ryan Moats, Victor Muslin, Kenneth Peirce, Stephen Farrell,
Sumit Vakil, John R. Vollbrecht, Jeff Weisberg, Jon Wood and Glen
Zorn

14.0

21.0 Authors' Addresses

Questions about this memo can be directed to:

Pat R. Calhoun
Network and Security Research Center, Sun Laboratories
Sun Microsystems, Inc.
15 Network Circle
Menlo Park, California, 94025
USA

Phone: +1 650-786-7733
Fax: +1 650-786-6445
E-mail: pcalhoun@eng.sun.com

Calhoun et al. expires July 2001 [Page 54]

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Allan C. Rubens
Tut Systems, Inc.
220 E. Huron, Suite 260
Ann Arbor, MI 48104
USA

Phone: +1 734-995-1697
E-Mail: arubens@tutsys.com

Haseeb Akhtar
Wireless Technology Labs
Nortel Networks
2221 Lakeside Blvd.

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Richardson, TX 75082-4399
USA

Phone: +1 972-684-8850
E-Mail: haseeb@nortelnetworks.com

Erik Guttman
Solaris Advanced Development
Sun Microsystems, Inc.
Eichhoelzelstr. 7
74915 Waibstadt
Germany

Phone: +49-7263-911-701
E-mail: erik.guttman@germany.sun.com

15.0

22.0 Full Copyright Statement

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this docu-
ment itself may not be modified in any way, such as by removing the
copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of develop-
ing Internet standards in which case the procedures for copyrights
defined in the Internet Standards process must be followed, or as
required to translate it into languages other than English. The

Calhoun et al. expires July 2001 [Page 55]

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limited lim-
ited permissions granted above are perpetual and will not be revoked
by the Internet Society or its successors or assigns. This document
and the information contained herein is provided on an "AS IS" basis
and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS DIS-
CLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.

16.0

23.0 Expiration Date

This memo is filed as <draft-ietf-aaa-diameter-00.txt> <draft-ietf-aaa-diameter-01.txt> and expires in
July
August 2001.

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Appendix A. Diameter Service Template

The following service template describes the attributes used by Diam-
eter servers to advertise themselves. This simplifies the process of
selecting an appropriate server to communicate with. A Diameter
client can request specific Diameter servers based on characteristics
of the Diameter service desired (for example, an AAA server to use
for accounting.)

Name of submitter: "Erik Guttman" <Erik.Guttman@sun.com>
Language of service template: en

Security Considerations:
Diameter clients and servers use various cryptographic mechanisms
to protect communication integrity, confidentiality as well as
perform end-point authentication. It would thus be difficult if
not impossible for an attacker to advertise itself using SLPv2 and
pose as a legitimate Diameter peer without proper preconfigured
secrets or cryptographic keys. Still, as Diameter services are
vital for network operation it is important to use SLPv2 authenti-
cation to prevent an attacker from modifying or eliminating ser-
vice advertisements for legitimate Diameter servers.

Template text:
-------------------------template begins here-----------------------
template-type=service:diameter

template-version=0.0

template-description=
The Diameter protocol is defined by draft-ietf-aaa-diameter-00.txt

template-url-syntax=
url-path= ; The standard service URL syntax is used.
; For example: 'service:diameter://aaa.example.com:1812

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supported-extensions= string L M
# This attribute lists the Diameter extensions supported by the
# AAA implementation. The extensions currently defined are:
# Extension Name Defined by
# --------------- -----------------------------------
# NASREQ draft-ietf-aaa-diameter-nasreq-00.txt
# MobileIP draft-ietf-aaa-diameter-mobileip-00.txt
# Accounting draft-ietf-aaa-diameter-accounting-00.txt
# Strong Security draft-calhoun-diameter-strong-crypto-05.txt
# Resource Management draft-calhoun-diameter-res-mgmt-06.txt
#
# Notes:
# . Diameter implementations support one or more extensions.
# . Additional extensions may be defined in the future.
# An updated service template will be created at that time.
#
NASREQ,MobileIP,Accounting,Strong Security,Resource Management

supported-transports= string L M
SCTP
# This attribute lists the supported transports that the Diameter
# implementation accepts. Note that a compliant Diameter
# implementation MUST support SCTP, though it MAY support other
# transports, too.
SCTP,TCP

-------------------------template ends here-----------------------

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----