WDIFF

draft-ietf-ngtrans-isatap-18.txt --> draft-ietf-ngtrans-isatap-19.txt

Network Working Group F. Templin
Internet-Draft Nokia
Expires: August 4, 15, 2004 T. Gleeson
Cisco Systems K.K.
M. Talwar
D. Thaler
Microsoft Corporation
February 4, 16, 2004

Internet/Site

Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
draft-ietf-ngtrans-isatap-18.txt
draft-ietf-ngtrans-isatap-19.txt

Status of this Memo

This document is an Internet-Draft and is subject to all provisions
of Section 10 of RFC2026.

Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on August 4, 15, 2004.

Abstract

The Internet/Site Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) connects
IPv6 hosts/routers over IPv4 networks. ISATAP views the IPv4 network
as a link layer for IPv6 and views other nodes on the network as
potential IPv6 hosts/routers. ISATAP supports automatic tunneling and
a tunnel interface management abstraction similar to the Non-
Broadcast, Multiple Access (NBMA) and ATM Permanent/Switched Virtual
Circuit (PVC/SVC) models.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. ISATAP Conceptual Model . . . . . . . . . . . . . . . . . . . 4 5
5. Node Requirements . . . . . . . . . . . . . . . . . . . . . . 5 6
6. Addressing Requirements . . . . . . . . . . . . . . . . . . . 5 7
7. Configuration and Management Requirements . . . . . . . . . . 6 8
8. Automatic Tunneling . . . . . . . . . . . . . . . . . . . . . 10 12
9. Neighbor Discovery for ISATAP Interfaces . . . . . . . . . . . 15 17
10. Other Requirements for Control Plane Signaling . . . . . . . . 18
11. Security considerations . . . . . . . . . . . . . . . . . . . 18
12. 20
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
13. 20
12. IAB Considerations . . . . . . . . . . . . . . . . . . . . . . 19
14. 20
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20 22
A. Major Changes . . . . . . . . . . . . . . . . . . . . . . . . 21 23
B. Example ISATAP Driver API . . . . . . . . . . . . . . . . . . 21
C. The IPv6 Minimum MTU . . . . . . . . . . . . . . . . . . . . . 24
D. 23
C. Modified EUI-64 Addresses in the IANA Ethernet Address Block . 24
E.
D. Proposed ICMPv6 Code Field Types . . . . . . . . . . . . . . . 25
Normative References . . . . . . . . . . . . . . . . . . . . . 25
Informative References . . . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 29 28
Intellectual Property and Copyright Statements . . . . . . . . 30 29

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1. Introduction

This document specifies a simple mechanism called the Internet/Site Intra-Site
Automatic Tunnel Addressing Protocol (ISATAP) that connects IPv6
[RFC2460] hosts/routers over IPv4 [STD0005] [STD5] networks. Dual-stack
(IPv6/IPv4) nodes use ISATAP to automatically tunnel IPv6 packets in
IPv4, i.e., ISATAP views the IPv4 network as a link layer for IPv6
and views other nodes on the network as potential IPv6 hosts/routers.

ISATAP enables automatic tunneling whether global or private IPv4
addresses are used, and supports a tunnel interface management
abstraction similar to the Non-Broadcast, Multiple Access (NBMA)
[RFC2491] and ATM Permanent/Switched Virtual Circuit (PVC/SVC)
[RFC2492] models.

The main objectives of this document are to: 1) describe the ISATAP
conceptual model, 2) specify addressing requirements, 3) discuss
configuration and management requirements, 4) specify automatic
tunneling using ISATAP, 5) specify operational aspects of IPv6
Neighbor Discovery, and 6) discuss IANA and Security considerations.

This document surveys all IETF v6ops WG documents current up to
February 4, 16, 2004.

2. Requirements

The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in [BCP0014]. [BCP14].

This document also makes use of internal conceptual variables to
describe protocol behavior and external variables that an
implementation must allow system administrators to change. The
specific variable names, how their values change, and how their
settings influence protocol behavior are provided to demonstrate
protocol behavior. An implementation is not required to have them in
the exact form described here, so long as its external behavior is
consistent with that described in this document.

3. Terminology

The terminology of [STD0003][RFC2460][RFC2461][RFC3582] [STD3][RFC2460][RFC2461][RFC3582] applies to this
document. The following additional terms are defined:

ISATAP node:
a node that implements the specifications in this document.

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ISATAP daemon:
an ISATAP node's server application that uses an ISATAP driver API for control
plane signaling and tunnel interface configuration/management.

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ISATAP driver:
an ISATAP node's network driver module that provides an API for control
plane signaling and tunnel interface configuration/
management. configuration/management.
Also provides an engine for tunneled a packet
encapsulation, decapsulation encapsulation/decapsulation engine, and forwarding. an
embedded gateway function (see: [STD3], section 3.3.4.2).

logical interface:
an IPv6 address or a configured tunnel interface associated with
an ISATAP interface. interface (see: [STD3], section 3.3.4.1).

ISATAP interface:
an ISATAP node's point-to-multipoint IPv6 interface for automatic
IPv6-in-IPv4 tunneling. Provides that provides a
control plane interface for the ISATAP daemon and a user forwarding
plane nexus for its associated logical interfaces.

ISATAP interface identifier:
an IPv6 interface identifier with an embedded IPv4 address
constructed as specified in section 6.1.

ISATAP address:
an IPv6 unicast address assigned on an ISATAP interface with an
on-link prefix and an ISATAP interface identifier.

locator:
an IPv4 address-to-interface mapping, i.e., a node's IPv4 address
and the index for it's associated interface.

locator set:
a set of locators associated with a tunnel interface, where each
locator in the set belongs to the same site.

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4. ISATAP Conceptual Model

ISATAP nodes typically act as a host on some interfaces and as a
router on other interfaces; the distinction between host and router
is made per are advertising interface.

ISATAP IPv6 interfaces that provide a
point-to-multipoint abstraction for IPv6-in-IPv4 tunneling. They
provide a user forwarding plane nexus (used by the ISATAP driver) for tunneling
packets on behalf of
their associated logical interfaces. They also provide a control
plane interface (used by the ISATAP daemon) for tunnel configuration signaling
between the ISATAP daemon and prospective peers (e.g., via IPv6
Neighbor Discovery messages, DNS queries, etc.).
signaling.

The ISATAP driver sends tunneled encapsulates packets via the node's IPv4 stack for transmission according to the sending interface's encapsulation parameters.
parameters associated with its logical interfaces. It also determines
the correct interface to receive each tunneled packet

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decapsulation, and provides an embedded gateway function.

The ISATAP daemon configures and manages tunnels via an API provided
by the ISATAP driver
API. driver. Each such configured tunnel provides a nexus
for multiple applications using IPv6 addresses as application
identifiers. Each such application identifier provides a nexus for
multiple sessions. In summary, each configured tunnel provides a
point-to-point connection between peers that can support multiple
applications and multiple instances of each application.

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The following example diagram depicts the ISATAP conceptual model:

<-- IPv6-enabled applications -->
+----+ +---------------------------------------------+
|I D| | IPv6 Stack |
|S a| | |
|A e| | <-- IPv6 addresses --> |
|T m| | +--+ +--+ +--+ +--+ +--+ +--+ +--+ +--+ |
|A o| | |v6| |v6| |v6| |v6| |v6| |v6| |v6| ... |v6| |
|P n| | +--+ +-++ ++-+ ++-+ ++++ ++-+ +-++ +-++ |
+-+--+ +---/---/----|----|---/-|--|-\----|--------|--+
| / / | | / | | \ | | <----+
x / / | | / | | \ | | I |
/ / +--++ +++-+ +--++ ++-++ +-+-+ S |
/ / |tun| |tun| |tun| |tun| ... |tun| A |
/ / +-+-+ +--++ +-+-+ ++--+ +-+-+ T |
/ / | \ | / | A |
x / / x | x \ | / x | P |
| / / | | | \ | / | | |
+--+---+---+ +------+---+ +-----+-+-++ +--------+-+ D |
|ISATAP I/F| |ISATAP I/F| |ISATAP I/F| .. |ISATAP I/F| r |
| (site 1) | | (site 1) | | (site 3) | | (site n) | i |
+---+----+++ +-++-----+-+ +-+-----+-++ +------+---+ v |
| | \ / | | | | \ | e |
| | \/ | | | | \ | r |
| | /\ | | | | \ | <----+
+---|----|-/--\-|-----|-----|-----|-----\ -------|---+
| +-+-+ +++-+ +++-+ +-+-+ +-+-+ +-+-+ +--++ +-+-+ |
| |loc| |loc| |loc| |loc| |loc| |loc| |loc| .. |loc| |
| +-+-+ +--++ +---+ +---+ +-+-+ +-+-+ +-+-+ +-+-+ |
| | / / / \ | / / |
| | / / +---+ \ | / / |
| | / / / \ | / / |
| | / / / IPv4 Stack \ | / / |
+-+-+-+--+-+--+--------+--+------+++------+-+------+-+
|IPv4 I/F| |IPv4 I/F| |IPv4 I/F| .... |IPv4 I/F|
|(site 1)| |(site 2)| |(site 3)| |(site n)|
+--------+ +--------+ +--------+ +--------+

5. Node Requirements

ISATAP nodes implement observe the common functionality required by requirements in
[NODEREQ]
as well as and the DNS requirements in ([MECH], section 2.2). They
also implement the additional features specified in this document.

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6. Addressing Requirements

6.1 ISATAP Interface Identifiers

ISATAP interface identifiers are constructed in Modified EUI-64
format ([ADDR], appendix A). They are formed by concatenating the
24-bit IANA OUI (00-00-5E), the 8-bit hexadecimal value 0xFE, and a
32-bit IPv4 address in network byte order ([AUTH], section 3.4). order.

The format for ISATAP interface identifiers is given below (where 'u'
is the IEEE univeral/local bit, 'g' is the IEEE group/individual bit,
and the 'm' bits represent the concatenated IPv4 address):

|0 1|1 3|3 4|4 6|
|0 5|6 1|2 7|8 3|
+----------------+----------------+----------------+----------------+
|000000ug00000000|0101111011111110|mmmmmmmmmmmmmmmm|mmmmmmmmmmmmmmmm|
+----------------+----------------+----------------+----------------+

When the IPv4 address is known to be globally unique, the 'u' bit is
set to 1; otherwise, the 'u' bit is set to 0 ([ADDR], section 2.5.1).
See: Appendix D C for additional non-normative details.

6.2 ISATAP Addresses

Any IPv6 unicast address ([ADDR], section 2.5) that contains an
ISATAP interface identifier constructed as specified in section 6.1
and an on-link prefix on an ISATAP interface is considered an ISATAP
address.

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6.3 Multicast/Anycast

ISATAP interfaces recognize a node's required IPv6 multicast/anycast
addresses ([ADDR], section 2.8).

For IPv6 multicast addresses of interest to local applications,
ISATAP nodes join the corresponding Organization-Local Scope IPv4
multicast groups ([RFC2529], section 6) on each interface that
appears in an ISATAP interface's locator set (see: section 7.2).

IPv6 multicast addresses of interest include a node's required
multicast addresses, and may also include e.g, the
'All_DHCP_Relay_Agents_and_Servers' and 'All_DHCP_Servers' multicast
addresses (i.e., if the node is configured as a DHCPv6 server
[RFC3315][RFC3633]), multicast
addresses discovered via MLD [RFC2710], etc.

Considerations for IPv6 anycast appear in [ANYCAST].

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6.4 Source/Target Link Layer Address Options

Source/Target Link Layer Address Options ([RFC2461], section 4.6.1)
for ISATAP have the following format:

+-------+-------+-------+-------+-------+-------+-------+--------+
| Type |Length | 0 | 0 | IPv4 Address |
+-------+-------+-------+-------+-------+-------+-------+--------+

Type:
1 for Source Link-layer address. 2 for Target Link-layer address.

Length:
1 (in units of 8 octets).

IPv4 Address:
A 32 bit IPv4 address, in network byte order ([AUTH], section
3.4). order.

ISATAP nodes use the specifications in ([MECH], section 3.8) that
pertain to sending and receiving Source/Target Link Layer Address
Options.

7. Configuration and Management Requirements

7.1 Network Management

ISATAP nodes MAY support network management; those that do SHOULD
support the following MIBs: [FTMIB][IPMIB][TUNMIB][TCPMIB][UDPMIB].

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This document defines no new MIB tables, nor extensions to any
existing MIB tables. Objects found in the MIBs listed above [FTMIB][IPMIB][TUNMIB] are
supported as described in the following subsections.

7.2 The ifRcvAddressTable

The ISATAP driver maintains ifRcvAddressTable as a bidirectional
association of locators with tunnel interfaces. Each locator in the
table includes a preferred an IPv4 address-to-interface mapping (i.e., a
preferred an IPv4
ipAddressEntry in the node's ipAddressTable) and a list of associated
tunnel interfaces. Each tunnel interface in the table has a
tunnelIfEntry and a list of associated locators, i.e., a "locator
set".

The ISATAP driver implements the following conceptual functions to
manage and search the ifRcvAddressTable:

7.2.1 RcvTableAdd(locator, tunnel_interface)

Creates a bidirectional association in the

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7.2.1 RcvTableAdd(locator, tunnel_interface)

Creates a bidirectional association in the ifRcvAddressTable between
the locator and tunnel interface, i.e., adds the locator to the
tunnel interface's locator set and adds the tunnel interface to the
locator's association list.

Returns success or failure.

7.2.2 RcvTableDel(locator, tunnel_interface)

Deletes ifRcvAddressTable entries according to the locator and tunnel
interface calling arguments as follows:

- if both arguments are NULL, garbage-collects the entire table.

- if both arguments are non-NULL, deletes the locator from the
tunnel interface's locator set and deletes the tunnel interface
from the locator's association list.

- if the locator is non-NULL and tunnel interface is NULL, deletes
the locator from the locator sets of all tunnel interfaces.

- if the locator is NULL and the tunnel interface is non-NULL,
deletes the tunnel interface from the association lists of all
locators.

Returns success or failure.

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7.2.3 RcvTableLocate(packet)

Searches the ifRcvAddressTable to locate the correct tunnel interface
to decapsulate a packet. First, determines the locator that matches
the packet's IPv4 destination address and ifIndex for the interface
the packet arrived on. Next, checks each tunnel interface in the
locator's association list for an exact match matches of tunnelIfEncapsMethod
with the packet's encapsulation type and an exact match of tunnelIfRemoteInetAddress
with the packet's IPv4 source address.

If there is no match on the packet's IPv4 source address, a tunnel
interface with a matching tunnelIfEncapsMethod and with
tunnelIfRemoteInetAddress set to 0.0.0.0 is selected. If there are
multiple matches, a tunnel interface with tunnelIfLocalInetAddress
that matches the packet's IPv4 destination address is preferred.

Returns a pointer to a tunnel interface if a match is found; else
NULL.

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7.3 ISATAP Driver API

The ISATAP driver implements an API for calling processes, used by, e.g., the ISATAP daemons, daemon,
startup scripts, manual command line entry, kernel processes, etc.
Access MUST be restricted to privileged users and applications. The API provides primitives for sending/receiving
control plane messages as well as creating, deleting, modifying,
ISATAP nodes implement the basic and
otherwise managing tunnel interfaces. An example (i.e., non-
normative) API is given in Appendix B. advanced APIs for IPv6
[RFC3493][RFC3542].

7.4 ISATAP Interface Creation/Configuration

ISATAP interfaces are created via the tunnelIfConfigTable, which
results in simultaneous creation of a tunnelIfEntry and a companion
ipv6InterfaceEntry. Each ISATAP interface configures a locator set,
where each locator in the set represents an IPv4 address-to-
interface address-to-interface
mapping for the same site (or, represents a mapping that is routable
on the global Internet). An ISATAP interface interfaces MUST NOT configure a
locator set that spans multiple sites.

ISATAP interfaces configure the following values for objects in
tunnelIfEntry:

- tunnelIfEncapsMethod is set to an IANATunnelType for "isatap".

- tunnelIfLocalInetAddress is set to an IPv4 address from the
interface's locator set.

- tunnelIfRemoteInetAddress is set to 0.0.0.0 to denote wildcard
match for remote tunnel endpoints.

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- other read-write objects in the tunnelIfEntry are configured as
for any tunnel interface.

ISATAP interfaces also configure are configured as advertising IPv6 interfaces and
set the following values for objects in ipv6InterfaceEntry:

- ipv6InterfaceType is set to "tunnel".

- ipv6InterfacePhysicalAddress is set to an octet string of zero
length to indicate that this IPv6 interface does not have a
physical address.

- ipv6InterfaceForwarding and, if necessary, and ip6Forwarding for the node are set to
"forwarding".

- other read-write objects in ipv6InterfaceEntry are configured as
for any IPv6 interface.

Finally,

ISATAP interfaces create an ipv6RouterAdvertEntry for the ISATAP interface is created
in ipv6RouterAdvertTable and set its

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ipv6RouterAdvertIfIndex object is
set to the same value as
ipv6InterfaceIfIndex. Other objects in ipv6RouterAdvertEntry are
configured as for any IPv6 router.

IPv6 address selection rules for ISATAP interfaces are specified in
[RFC3484].

7.5 Dynamic Creation of Configured Tunnels Tunnel Creation/Configuration

Configured tunnels are normally created by the ISATAP daemon in
dynamic response to a tunnel creation request. Configured tunnel
interfaces are configured request as for an ISATAP interfaces (see: section
7.4), except that
interface's associated logical interface; they inherit the locator
set of their associated ISATAP interface. Configured tunnels set the
following values for objects in tunnelIfEntry:

- tunnelIfEncapsMethod is set to an appropriate IANATunnelType
value.

- tunnelIfLocalInetAddress is set to an IPv4 address from the
interface's locator set.

- tunnelIfRemoteInetAddress is normally set to a
specific an IPv4 address for a remote the node
at the far end of the tunnel,
i.e., configured tunnels tunnel.

- other read-write objects in the tunnelIfEntry are normally configured as point-to-point.
Also, tunnelIfEncapsMethod
for the new entry any tunnel interface.

Configured tunnels set values for objects in ipv6InterfaceEntry as
follows:

- ipv6InterfaceType is set to an
IANATunnelType appropriate for the method of encapsulation.

Configured tunnels MAY be "bound" "tunnel".

- ipv6InterfacePhysicalAddress is set to an ISATAP interface such that
they inherit the ISATAP interface's locator set, e.g., for ease octet string of
management and zero
length to avoid misconfigurations.

Configured tunnels MAY also be created indicate that this IPv6 interface does not have a
physical address.

- other read-write objects in ipv6InterfaceEntry are configured as independent entities and
configure their own locator set, but (as
for ISATAP interfaces) they
MUST NOT configure a locator set that spans multiple sites. any IPv6 interface.

IPv6 address selection rules for configured tunnel interfaces are
specified in [RFC3484].

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7.6 Reconfigurations Due to IPv4 Address Changes

When a locator becomes deprecated (e.g., when an IPv4 address is removed from an IPv4 interface) the interface, its corresponding
locator SHOULD be removed from all tunnel interface associations locator sets via
RcvTableDel(locator, NULL).
Also, all tunnel interfaces NULL); tunnelIfEntrys that used the deprecated IPv4 address
as tunnelIfLocalInetAddress SHOULD also configure a different local
IPv4 address from their remaining locator set.

When a new IPv4 address is added to an IPv4 interface, the node MAY
add the corresponding new locator to the a tunnel interface's locator set for one or more
tunnel interfaces
via RcvTableAdd(locator, tunnel_interface), and MAY also set
tunnelIfLocalInetAddress for tunnel interfaces referenced by the
updated forwarding entries its tunnelIfEntry to the new address.

Methods for triggering the above changes, and for communicating IPv4
address changes to remote nodes, are out of scope.

8. Automatic Tunneling

ISATAP nodes use the basic tunneling mechanisms specified in [MECH].
The following additional specifications are also used:

8.1 Encapsulation

The ISATAP driver encapsulates IPv6 packets in IPv4 using various
encapsulation methods, including ip-protocol-41 (e.g., 6over4
[RFC2529], 6to4 [RFC3056], IPv6-in-IPv4 configured tunnels [MECH],
isatap, etc.), UDP [STD0006] [STD6] port 3544, and others.

AH [RFC2402] and/or ESP [RFC2406]

Security processing (e.g., [RFC2402][RFC2406], etc.), upper layer
fragmentation [RFC3542] and header compression for the packet's inner
headers are performed prior to encapsulation.

8.1.1 NAT Traversal

Native IPv6 and/or ip-protocol-41 encapsulation provides sufficient
functionality to support peer-to-peer communications when both between peers that reside
within the same site (i.e., the same enterprise network). When the
remote peer resides within is in a different site, NAT traversal via UDP/IPv4
encapsulation MAY be necessary.

When an ISATAP node determines that NAT traversal is necessary to
reach a particular peer, it encapsulates IPv6 packets using UDP/IPv4
encapsulation with a UDP destination
port of 3544. 3544 encapsulation. This determination may come through, e.g.,
first attempting communications via ip-
protocol-41 ip-protocol-41 then failing over
to UDP/IPv4 port 3544 encapsulation, administrative knowledge that a
NAT traversal will occur along is on the path, etc.

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When UDP/IPv4 port 3544 encapsulation is used, the specifications in
this document apply the same as for any form of encapsulation
supported by ISATAP.

8.1.2 Multicast

ISATAP interfaces encapsulate packets with IPv6 multicast destination
addresses using a mapped Organization-Local Scope IPv4 multicast
address ([RFC2529], section 6) as the destination address in the
encapsulating IPv4 header.

8.2 Tunnel MTU and Fragmentation

Encapsulated packets sent by the ISATAP driver may incur require host-based
IPv4 fragmentation, fragmentation in order to satisfy the 1280 byte IPv6 minimum
MTU, e.g., when the underlying physical link has a small IPv4 MTU [BCP0048]. In
such cases, host-based IPv4 [BCP48].
While this intentional fragmentation is required to satisfy the
1280 byte IPv6 minimum MTU, and is not considered harmful [FRAG]. On
the other hand, harmful,
unmitigated IPv4 fragmentation caused by the network can cause poor performance.
performance [FRAG]. For example, since the minimum IPv4 fragment
size is only 8 bytes [STD0005], network middleboxes could
shred [STD5], a single 1280 byte tunneled encapsulated packet
could be shredded by the network into as many as 160 IPv4 fragments. fragments
with obvious negative performance implications.

ISATAP uses the MTU and fragmentation specifications in ([MECH],
section 3.2) and the Maximum Reassembly Unit (MRU) specifications in
([MECH], section 3.6), which provide sufficient measures for avoiding
excessive IPv4 fragmentation in certain controlled environments
(e.g., 3GPP operator networks, enterprise networks, etc). To minimize
IPv4 fragmentation and improve performance in general use case
scenarios, ISATAP nodes SHOULD add the following simple
instrumentation to the IPv4 reassembly cache:

When the initial fragment of an encapsulated packet arrives, the
packet's IPv4 reassembly timer is set to 1 second (i.e., the worst
case store-and-forward delay budget for a 1280 byte packet). If an
encapsulated packet's IPv4 reassembly timer expires:

- If enough contiguous leading bytes of the packet have arrived
(see: section 8.6), reassemble the packet from all fragments
received. (Otherwise, garbage-collect the reassembly buffer and
return from processing.) During reassembly, copy using zero-filled or, or
heuristically-chosen replacement data bytes in place of any
missing fragments. (Otherwise, garbage-collect the reassembly
buffer and return from processing.)

- Mark the packet as "INCOMPLETE", and also mark it with a
"TOTAL_BYTES" an
"ACTUAL_BYTES" length that encodes the total actual number of data bytes
in fragments that arrived.

- Deliver the packet to the ISATAP driver as though reassembly had

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succeeded.

- Do driver, and do not send an ICMPv4
"time exceeded" message [STD0005]. [STD5].

Appendix C B provides informative text on the derivation of the 1280
byte IPv6 minimum MTU.

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8.3 Handling ICMPv4 Errors

ISATAP interfaces SHOULD process ARP failures and persistent ICMPv4
errors as link-specific information indicating that a path to a
neighbor may have failed ([RFC2461], section 7.3.3).

8.4 Link-Local Addresses

ISATAP interfaces use link local addresses constructed as specified
in section 6.1 of this document.

8.5 Neighbor Discovery over Tunnels

The specification in ([MECH], section 3.8) is used; the additional
specification for neighbor discovery in section 9 of this document
are also used.

8.6 Decapsulation/Filtering

ISATAP nodes typically arrange for the ISATAP driver to receive all
IPv4-encapsulated IPv6 packets that are addressed to one of the
node's IPv4 addresses. Examples include ip-protocol-41 (e.g., 6to4,
6over4, configured tunnels, isatap, etc.), UDP/IPv4 port 3544, and
others. The ISATAP driver uses the decapsulation and filtering
specifications in ([MECH], section 3.6), and processes each packet
according to the following steps:

1. Locate the correct tunnel interface to receive the packet (see:
section 7.2.3). If not found, silently discard the packet and
return from processing.

2. If the tunnel uses header compression, reconstitute headers. If
header reconstitution fails, silently discard the packet and
return from processing.

3. Verify that the packet's IPv4 source address is correct for the
encapsulated IPv6 source address. For packets received on a
configured tunnel interface, verification is exactly as specified
in ([MECH], section 3.6).

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For packets received on an ISATAP interface, the IPv4 source
address is correct if:

- the IPv6 source address is an ISATAP address that embeds the
IPv4 source address in its interface identifier, or:

- the IPv6 source address is the address of an IPv6 neighbor on
an ISATAP interface associated with the locator that matched

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the packet (see: section 7.2.3), or:

- the IPv4 source address is a member of the Potential Router
List (see: section 9.1).

If the IPv4 source address is incorrect, silently discard the
packet and return from processing.

4. Perform IPv4 ingress filtering (optional; disabled by default)
then decapsulate the packet. packet but do not discard encapsulating
headers. If the IPv6 source address is invalid (see: [MECH],
section 3.6), silently discard the packet and return from
processing.

For UDP port 3544 packets received on an ISATAP interface, if the
IPv6 source address is an ISATAP link local address with the 'u'
bit set to 0 and an embedded IPv4 address that does not match the
IPv4 source address (see: section 6), rewrite the IPv6 source
address to inform upper layers of the sender's mapped UDP port
number and IPv4 source address. Specific rules for rewriting the
IPv6 source address are established during ISATAP interface
configuration.

Next, discard encapsulating headers and continue processing the
encapsulated IPv6 packet.

5. Perform ingress filtering on the IPv6 source address (see:
[MECH], section 3.6). Next, determine the correct transport
protocol listener [FLOW] if the packet is destined to the
localhost; otherwise, perform an IPv6 forwarding table lookup and
site border/firewall filtering (see: [UNIQUE], section 6).

If the packet cannot be delivered, the driver SHOULD send an
ICMPv6 Destination Unreachable message ([RFC2463], section 3.2)
to the packet's source. The message SHOULD select as its source
address an IPv6 address from the outgoing interface (if the
packet was destined to the localhost) or an ingress-wise correct
IPv6 address from the interface that would have forwarded the
packet had it not been filtered.

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The Code field of the message is set as follows:

- if there is no route to the destination, the Code field is set
to 0 (see: [RFC2463], section 3.1).

- if communication with the destination is administratively
prohibited, the Code field is set to 1 ([RFC2463], section
3.1).

- if the packet is destined to the localhost, but the transport
protocol has no listener, the Code field is set to 4

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([RFC2463], section 3.1).

- if the packet's destination is beyond the scope of the source
address, the Code field is set to 2 (see: IANA
Considerations).

- if the packet was dropped due to ingress filtering policies,
the Code field is set to 5 (see: IANA Considerations).

- if the packet is dropped due to a reject route, the Code field
is set to 6 (see: IANA Considerations).

- if the packet was received on a point-to-point link and
destined to an address within a subnet assigned to that same
link, or if the reason for the failure to deliver cannot be
mapped to any of the specific conditions listed above, the
Code field is set to 3 ([RFC2463], section 3.2).

After sending the ICMPv6 Destination Unreachable message, discard
the packet and return from processing.

6. If the packet is "INCOMPLETE" (see section 8.2) send prepare an
authenticated, unsolicited Router Advertisement message
([RFC2461], section 6.2.4) with an MTU option that encodes the
maximum of "ACTUAL_BYTES" and (68 bytes minus the size of
encapsulating headers.)

The IPv6 destination address in the Router Advertisement message
is set to the packet's IPv6 source address
with an address, and the message is
reverse-encapsulated and returned to the node that sent the
"INCOMPLETE" packet, i.e., it is NOT presented to the native IPv6
stack for transmission.

The 68 byte minimum MTU option is due to the requirement that encodes "TOTAL_BYTES". every
Internet module must be able to forward a datagram of 68 octets
without further fragmentation ([STD5], Internet Protocol, section
3.2).

7. Discard encapsulating headers. If the packet was destined to a
remote host, forward the packet and return from processing.
Otherwise, apply AH [RFC2402] or ESP
[RFC2406] security processing (if necessary), (e.g., [RFC2402][RFC2406],
etc.), and deliver place the decapsulated packet by placing it in a buffer for upper layers. The
buffer may be, e.g., the IPv6 reassembly cache, an application's
mapped data buffer [RFC3542], etc.

If there is clear evidence that upper layer reassembly has
stalled, an ICMPv6 Packet Too Big message [RFC1981] MAY be sent
to the packet's source address with an MTU value indicating a
size that is likely to incur successful reassembly. Some

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successful reassembly. Some applications may realize greater
efficiency by accepting partial information from "INCOMPLETE"
packets (see: section 8.2) and requesting selective
retransmission of missing portions.

9. Neighbor Discovery for ISATAP Interfaces

ISATAP nodes use the neighbor discovery mechanisms specified in
[RFC2461] along with securing mechanisms (e.g., [SEND]) to create/
change neighbor cache entries and to provide control plane signaling
for automatic tunnel configuration. ISATAP interfaces also implement
the following specifications:

9.1 Conceptual Model Of A Host

To the list of Conceptual Data Structures ([RFC2461], section 5.1),
ISATAP interfaces add:

Potential Router List
A set of entries about potential routers; used to support the
mechanisms specified in section 9.2.2.1. Each entry ("PRL(i)")
has an associated timer ("TIMER(i)"), and an IPv4 address
("V4ADDR(i)") that represents a router's advertising ISATAP
interface.

9.2 Router and Prefix Discovery

9.2.1 Router Specification

As permitted by

The Router Specification in ([RFC2461], section 6.2.6), the ISATAP daemon SHOULD
send unicast Router Advertisement messages to the soliciting node's
address when the solicitation's source address 6.2) is not the unspecified
address. (Router used. Router
Advertisements sent on ISATAP interfaces MAY include information
delegated via DHCPv6 [RFC3633]).

Routers Router Advertisements sent on ISATAP
interfaces MUST NOT send include a prefix options option containing a preferred
lifetime greater than the valid lifetime.

9.2.2 Host Specification

The Host Specification in ([RFC2461], section 6.3) is used. ISATAP
interfaces add the following specifications:

9.2.2.1 Host Variables

To the list of host variables ([RFC2461], section 6.3.2), ISATAP
interfaces add:

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PrlRefreshInterval
Time in seconds between successive refreshments of the PRL after
initialization. It SHOULD be no less than 3600 seconds. The designated value of all 1's (0xffffffff)
represents infinity.
Default: 3600 seconds

MinRouterSolicitInterval
Minimum time in seconds between successive solicitations of the
same advertising ISATAP interface. The designated value of all 1's
(0xffffffff) represents infinity.
Default: 900 seconds

9.2.2.2 Potential Router List Initialization

ISATAP nodes provision an ISATAP interface's PRL with IPv4 addresses
discovered via manual configuration, a DNS fully-qualified domain name (FQDN) [STD0013], [STD13],
manual configuration, a DHCPv4 option, a DHCPv4 vendor-specific
option, or an unspecified alternate method.

FQDNs are established via manual configuration or an unspecified
alternate method. FQDNs are resolved into IPv4 addresses through
lookup in a static host file,
querying the DNS service, querying a site-specific name service,
static host file lookup, or an unspecified alternate method.

When the node provisions an ISATAP interface's PRL with IPv4
addresses, it sets a timer for the interface (e.g.,
PrlRefreshIntervalTimer) to PrlRefreshInterval seconds. The node re-
initializes the PRL as specified above when PrlRefreshIntervalTimer
expires, or when an asynchronous re-initialization event occurs. When
the node re-initializes the PRL, it resets PrlRefreshIntervalTimer to
PrlRefreshInterval seconds.

9.2.2.3 Processing Received Router Advertisements

The

To the list of checks for validating Router Advertisement messages
([RFC2461], section 6.1.1), ISATAP daemon processes interfaces add:

- IP Source Address is an ISATAP link-local address that embeds
V4ADDR(i) for some PRL(i).

Valid Router Advertisements (RAs) received on an ISATAP interface are
processed exactly as specified in ([RFC2461], section 6.3.4). The DHCPv6 specification
[RFC3315] is the stateful mechanism associated with the M and O bits.

When the ISATAP daemon receives a 6.3.4) except
that, for unicast Router Advertisement with Advertisements that include an MTU
option from a router at option,
the far end of a tunnel, it records MTU value does not alter the ISATAP interface LinkMTU. Instead,
the
advertised MTU value, value is recorded, e.g., in the node's IPv6 routing forwarding table. If the
MTU value
IPv6 destination address is less than the MTU one of the tunnel interface, node's own unicast addresses,
the MTU value is recorded in such a way that the node will perform upper layer fragmentation (i.e., above the IPv4 link layer)
[RFC3542] will be used to reduce the size of the IPv4 encapsulated packets it sends
sent via the router. The recorded value is aged as for IPv6 path MTU information [RFC1981].

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For Router Advertisement messages that include prefix options, Route

information options [DEFLT] and/or non-zero values in the Router
Lifetime, the ISATAP daemon resets TIMER(i) to schedule the next
solicitation event (see: section 9.2.2.4). Let "MIN_LIFETIME" be the
minimum value in the Router Lifetime or the lifetime(s) encoded in
options included in the RA message. Then, TIMER(i) is reset as
follows:

TIMER(i) = MAX((0.5 * MIN_LIFETIME), MinRouterSolicitInterval) [RFC1981].

9.2.2.4 Sending Router Solicitations

To the list of events after which RSs Router Solicitation messages may be
sent ([RFC2461], section
6.3.2), 6.3.7), ISATAP interfaces add:

- TIMER(i) for some PRL(i) expires.

Since unsolicited Router Solicitations MAY Advertisements may be sent to an ISATAP link-local address that
embeds V4ADDR(i) for some PRL(i) instead of the All-Routers incomplete (and, since
multicast
address.

9.3 Address Resolution and Neighbor Unreachability Detection

9.3.1 Address Resolution

The specification in ([RFC2461], unsolicited Router Advertisements may not arrive) ISATAP
nodes schedule periodic events to solicit Router Advertisements from
certain PRL(i)'s. When this periodic solicitation is used, after
sending the initial solicitation and receiving a valid Router
Advertisement message from PRL(i) with a non-zero Router Lifetime the
node sets TIMER(i) to schedule the first periodic event.

The TIMER(i) value SHOULD be set such that the next periodic event
will trigger a solicited Router Advertisement message before the
expiration of remaining lifetimes stored for this PRL(i), including
the Router Lifetime, Valid Lifetimes received in Prefix Information
Options, and Route Lifetimes received in Route Information Options
[DEFLT]. The TIMER(i) value MUST be set to no less than
MinRouterSolicitInterval seconds, where MinRouterSolicitInterval is
configurable for the node with a conservative default value.

When TIMER(i) expires, the node sends Router Solicitation messages as
specified in ([RFC2461], section 6.3.7) except that the messages use
an ISATAP link-local address that embeds V4ADDR(i) as the IPv6
destination address (i.e., instead of the All-Routers multicast
address). If remaining lifetimes for this PRL(i) have not yet expired
and the PRL(i) is still in use, TIMER(i) is reset as described above.

9.3 Address Resolution and Neighbor Unreachability Detection

9.3.1 Address Resolution

The specification in ([RFC2461], section 7.2) is used. ISATAP
addresses for which the neighbor/router's neighbor's link-layer address cannot
otherwise be determined (e.g., from a neighbor cache entry) are
resolved to link-layer addresses by a static computation, i.e., the
last four octets are treated as an IPv4 address.

Hosts SHOULD perform an initial reachability confirmation by sending
Neighbor Solicitation message(s) and receiving a Neighbor
Advertisement message (NS messages are sent to the target's unicast
address). message. Routers MAY perform this initial reachability
confirmation, but this might not scale in all environments.

All nodes MUST send solicited Neighbor Advertisements on

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interfaces ([RFC2461], section 7.2.4). February 2004

9.3.2 Neighbor Unreachability Detection

Hosts SHOULD perform Neighbor Unreachability Detection ([RFC2461],
section 7.3). Routers MAY perform neighbor unreachability detection,
but this might not scale in all environments.

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10. Other Requirements for Control Plane Signaling

10.1 Domain Name System (DNS)

The specifications in ([MECH], section 2.2) are used. Additional Security considerations

Security considerations are found in [DNSOPV6].

10.2 Linklocal Multicast Name Resolution (LLMNR) the normative references apply. Also:

- ISATAP nodes SHOULD implement Link Local Multicast Name Resolution
[LLMNR], since they will commonly be deployed observe the security considerations outlined in environments
[SENDPS]; use of (e.g.,
home networks, ad-hoc networks, [RFC2402][RFC2406], etc.) with no DNS service.

10.3 Node Information Queries

ISATAP nodes MAY implement Node Information Queries as specified in
[NIQUERY], since they may help the querier discover some subset of
the responder's addresses.

11. Security considerations

The security considerations in the normative references apply; also: is not always
feasible.

- site border routers SHOULD install a black hole reject route for the IPv6
prefix FC00::/7 to insure that packets with local IPv6 destination
addresses will not be forwarded outside of the site via a default
route.

- administrators MUST ensure that lists of IPv4 addresses
representing the advertising ISATAP interfaces of PRL members are
well maintained.

12.

11. IANA Considerations

The IANA is instructed to specify the format for Modified EUI-64
address construction ([ADDR], Appendix A) in the IANA Ethernet
Address Block. The text in Appendix D C of this document is offered as
an example specification. The current version of the IANA registry
for Ether Types can be accessed at at:
http://www.iana.org/assignments/ethernet-numbers.

The IANA is instructed to assign the new ICMPv6 code field types
found in Appendix E D of this document for the ICMPv6 Destination
Unreachable message. The policy for assigning new ICMPv6 code field
types is First Come First Served, as defined in [RFC2434]. [BCP26]. The current
version of the IANA registry for ICMPv6 type numbers can be accessed at
at:
http://www.iana.org/assignments/icmpv6-parameters.

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13.

12. IAB Considerations

[RFC3424] ("IAB Considerations for UNilateral Self-Address Fixing
(UNSAF) Across Network Address Translation") section 4 requires that
any proposal supporting NAT traversal must explicitly address the
following considerations:

13.1

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12.1 Problem Definition

The specific problem being solved is enabling IPv6 connectivity for
ISATAP nodes that are unable to communicate via ip-protocol-41 or
native IPv6.

13.2

12.2 Exit Strategy

ISATAP nodes use UDP/IPv4 encapsulation for NAT traversal as a last
resort. As soon as native IPv6 or ip-protocol-41 support becomes
available, ISATAP nodes will naturally cease using UDP/IPv4
encapsulation.

13.3

12.3 Brittleness

UDP/IPv4 encapsulation with ISATAP introduces brittleness into the
system in several ways: the discovery process assumes a certain
classification of devices based on their treatment of UDP; the
mappings need to be continuously refreshed, and addressing structure
may cause some hosts located beyond a common NAT to be unreachable
from each other.

ISATAP assumes a certain classification of devices based on their
treatment of UDP. There could be devices that would not fit into one
of these molds, and hence would be improperly classified by ISATAP.

The bindings allocated from the NAT need to be continuously
refreshed. Since the timeouts for these bindings is very
implementation specific, the refresh interval cannot easily be
determined. When the binding is not being actively used to receive
traffic, but to wait for an incoming message, the binding refresh
will needlessly consume network bandwidth.

13.4

12.4 Requirements for a Long Term Solution

The devices that implement the IPv4 NAT service should in the future
also become IPv6 routers.

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14.

13. Acknowledgments

The ideas in this document are not original, and the authors
acknowledge the original architects. Portions of this work were
sponsored through SRI International internal projects and government
contracts. Government sponsors include Monica Farah-Stapleton and
Russell Langan (U.S. Army CECOM ASEO), and Dr. Allen Moshfegh (U.S.
Office of Naval Research). SRI International sponsors include Dr.
Mike Frankel, J. Peter Marcotullio, Lou Rodriguez, and Dr. Ambatipudi
Sastry.

The following are acknowledged for providing peer review input: Jim
Bound, Rich Draves, Cyndi Jung, Ambatipudi Sastry, Aaron Schrader,
Ole Troan, Vlad Yasevich.

The following are acknowledged for their significant contributions:
Alain Durand, Hannu Flinck, Jason Goldschmidt, Nathan Lutchansky,
Karen Nielsen, Mohan Parthasarathy, Chirayu Patel, Art Shelest, Pekka
Savola, Margaret Wasserman, Brian Zill.

The authors acknowledge the work of Quang Nguyen on "Virtual
Ethernet" under the guidance of Dr. Lixia Zhang that proposed very
similar ideas to those that appear in this document. This work was
first brought to the authors' attention on September 20, 2002.

IAB considerations are the same as for Teredo. The diagram in section
4 was inspired by a similar diagram in RFC 3371.

The following individuals are acknowledged for their helpful insights
on path MTU discovery: Jari Arkko, Iljitsch van Beijnum, Jim Bound,
Ralph Droms, Alain Durand, Jun-ichiro itojun Hagino, Brian Haberman,
Bob Hinden, Christian Huitema, Kevin Lahey, Hakgoo Lee, Matt Mathis,
Jeff Mogul, Erik Nordmark, Soohong Daniel Park, Chirayu Patel,
Michael Richardson, Pekka Savola, Hesham Soliman, Mark Smith, Dave
Thaler, Michael Welzl, Lixia Zhang and the members of the Nokia NRC/
COM Mountain View team.

"...and I'm one step ahead of the shoe shine,
Two steps away from the county line,
Just trying to keep my customers satisfied,
Satisfi-i-ied!" - Paul Simon, 1969

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Appendix A. Major Changes

Major changes from earlier versions to version 17:

- changed first words in title from "Intra-site" to "Internet/site"
to more accurately represent the functionality.

- new section on configuration/management.

- new appendices on tunnel driver API; IANA considerations.

- expanded section on MTU and fragmentation.

- expanded sections on encapsulation/decapsulation.

- specified relation to IPv6 Node Requirements.

- introduced distinction between control; user planes.

- specified multicast mappings.

- revised neighbor discovery, address autoconfiguration, IANA
considerations and security considerations sections.

Appendix B. Example ISATAP Driver API

An ISATAP driver API should include primitives for sending and
receiving control plane messages as well as primitives for tunnel
configuration/management such as the following non-normative
examples:

B.1 ISATAP_SEND, ISATAP_RECEIVE Primitives

Description:
Sends/Receives control plane messages via the
ISATAP driver (e.g., via a routing socket, etc.)

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B.2 ISATAP_CREATE Primitive

Description:
Creates a new tunnel interface and an associated IP
interface by creating a row in tunnelIfConfigTable.
Also optionally configures read-write objects for the
tunnel interface and adds locators to the receive address
table via RcvTableAdd(locator, tunnel_interface).
Required parameter:
- tunnelIfEncapsMethod.
Optional parameters:
- attributes for configuring read-write objects.
- list of locators to associate with tunnel interface.
Returns:
- ifIndex for the new tunnel interface, or a failure code.

B.3 ISATAP_DELETE Primitive

Description:
Deletes an existing tunnel interface by deleting the
corresponding row in tunnelIfConfigTable. Also frees
its locators via RcvTableDel(NULL, tunnel_interface).
Required parameter:
- ifIndex.
Returns:
- success or a failure code.

B.4 ISATAP_CONFIG Primitive

Description:
Configures attributes for an existing tunnel interface.
Also adds new locators via RcvTableAdd(locator,
tunnel_interface) and deletes old locators via
RcvTableDel(locator, tunnel_interface).
Required parameter:
- ifIndex.
Optional parameters:
- read-write objects for the tunnel interface.
- list of locators to associate with tunnel interface.
- list of locators to delete from association.
Returns:
- success or a failure code.

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B.5 ISATAP_BIND Primitive

Description:
Binds (or, creates then binds) a configured tunnel interface
to an ISATAP interface. The configured tunnel interface
inherits the ISATAP interface's locator set and the ISATAP
interface uses the encapsulation parameters associated with
the bound configured tunnel interface.
Required parameter:
- ifIndex for the ISATAP interface.
- ifIndex for the configured tunnel interface, or NULL.
Conditional parameter:
- if ifIndex for the configured tunnel is NULL,
tunnelIfEncapsMethod.
Optional parameters:
- attributes for configuring read-write objects for the
configured tunnel interface.
Returns:
- ifIndex for the configured tunnel, or a failure code.

B.6 ISATAP_GET Primitive

Description:
Copies configuration attributes from system table entries
associated with the specified tunnel interface into a
calling process' buffer.
Required parameter:
- ifIndex
- address of a buffer in calling process's memory.
- number Welzl, Lixia Zhang and the members of bytes available in the user's buffer.
Returns:
- Number Nokia NRC/
COM Mountain View team.

"...and I'm one step ahead of bytes written into the calling process'
buffer, or a failure code. shoe shine,
Two steps away from the county line,
Just trying to keep my customers satisfied,
Satisfi-i-ied!" - Paul Simon, 1969

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Appendix C. A. Major Changes

Major changes from earlier versions to version 17:

- new section on configuration/management.

- new appendices on IPv6 minimum MTU; IANA considerations.

- expanded section on MTU and fragmentation.

- expanded sections on encapsulation/decapsulation.

- specified relation to IPv6 Node Requirements.

- introduced distinction between control; forwarding planes.

- specified multicast mappings.

- revised neighbor discovery, address autoconfiguration, IANA
considerations and security considerations sections.

Appendix B. The IPv6 minimum MTU

The 1280 byte IPv6 minimum MTU was proposed by Steve Deering and
agreed through working group consensus in November 1997 discussions
on the IPv6 mailing list. The size was chosen to allow extra room for
link layer encapsulations without exceeding the Ethernet MTU of 1500
bytes, i.e., the practical physical cell size of the Internet. The
1280 byte MTU also provides a fixed upper bound for the size of IPv6
packets/fragments with a maximum store-and-forward delay budget of ~1
second assuming worst-case link speeds of ~10Kbps [BCP0048], [BCP48], thus
providing a convenient value for use in reassembly buffer timer
settings. Finally, the 1280 byte MTU allows transport connections
(e.g., TCP) to configure a large-enough maximum segment size for
improved performance even if the IPv4 interface that will send the
tunneled packets uses a smaller MTU.

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Appendix D. C. Modified EUI-64 Addresses in the IANA Ethernet Address Block

Modified EUI-64 addresses ([ADDR], Appendix A) in the IANA Ethernet
Address Block are formed as the concatenation of the 24-bit IANA OUI
(00-00-5E) with a 40-bit extension identifier. They have the
following appearance in memory (bits transmitted right-to-left within
octets, octets transmitted left-to-right):

0 23 63
| OUI | extension identifier |
000000ug00000000 01011110xxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx

When the first two octets of the extension identifier encode the
hexadecimal value 0xFFFE, the remainder of the extension identifier
encodes a 24-bit vendor-supplied id as follows:

0 23 39 63
| OUI | 0xFFFE | vendor-supplied id |
000000ug00000000 0101111011111111 11111110xxxxxxxx xxxxxxxxxxxxxxxx

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When the first octet of the extension identifier encodes the
hexadecimal value 0xFE, the remainder of the extension identifier
encodes a 32-bit IPv4 address, as specified in ([ISATAP], section
6.1) and address as follows:

0 23 31 63
| OUI | 0xFE | IPv4 address |
000000ug00000000 0101111011111110 xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx

Modified EUI-64 format interface identifiers are formed by inverting
the "u" bit, i.e., the "u" bit is set to one (1) to indicate
universal scope and it is set to zero (0) to indicate local scope
([ADDR], section 2.5.1).

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Appendix E. D. Proposed ICMPv6 Code Field Types

Three new ICMPv6 Code Field Type definitions are proposed for the
ICMPv6 Destination Unreachable message. The first proposes a new
definition for a currently-unassigned code type (2) in the ICMPv6
Type Numbers registry; the others propose new definitions for code
types (5) and (6). The code type field definition proposals appear
below:

Type Name Reference
---- ------------------------- ---------
1 Destination Unreachable [RFC2463]
Code 2 - beyond the scope of source address
5 - source address failed ingress policy
6 - reject route to destination

Normative References

[STD0003]

[BCP14] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.

[BCP26] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.

[STD3] Braden, R., "Requirements for Internet Hosts - Communication
Layers", STD 3, RFC 1122, October 1989.

[STD0005]

[STD5] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981.

[STD0006]

[STD6] Postel, J., "User Datagram Protocol", STD 6, RFC 768, August
1980.

[RFC1981] McCann, J., Deering, S. and J. Mogul, "Path MTU Discovery for
IP version 6", RFC 1981, August 1996.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

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[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26,
IP version 6", RFC 2434, October 1998. 1981, August 1996.

[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.

[RFC2461] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery
for IP Version 6 (IPv6)", RFC 2461, December 1998.

[RFC2463] Conta, A., and S. Deering, "Internet Control Message Protocol
(ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification",
RFC 2463, December 1998.

[RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4
Domains without Explicit Tunnels", RFC 2529, March 1999.

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[RFC3424] Daigle, L. and IAB, "IAB Considerations for UNilateral Self-
Address Fixing (UNSAF) Across Network Address Translation", RFC 3424,
November 2002.

[RFC3484] Draves, R., "Default Address Selection for Internet Protocol
version 6 (IPv6)", RFC 3484, February 2003.

[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
Stevens, "Basic Socket Interface Extensions for IPv6", RFC 3493,
February 2003.

[RFC3542] Stevens, W., Thomas, M., Nordmark, E. and T. Jinmei,
"Advanced Sockets Application Program Interface (API) for IPv6", RFC
3542, May 2003.

[RFC3582] Abley, J., Black, B. and V. Gill, "Goals for IPv6 Site-
Multihoming Architectures", RFC 3582, August 2003.

[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host
Configuration Protocol (DHCP) version 6", RFC 3633, December 2003.

[ADDR] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", draft-ietf-ipv6-addr-arch-v4 (work draft-ietf-ipv6-addr-arch-v4, Work in progress), Progress,
October 2003.

[AUTH] Reynolds, J. and R. Braden, "Instructions to Request for
Comments (RFC) Authors", draft-rfc-editor-rfc2223bis (work in
progress), August 2003.

[DEFLT] Draves, R. and D. Thaler, "Default Router Preferences and
More-Specific Routes", draft-ietf-ipv6-router-selection (work draft-ietf-ipv6-router-selection, Work in
progress),
Progress, December 2003.

[ISATAP] Templin, F., Gleeson, T., Talwar, M. and D. Thaler,
"Internet/Site Automatic Tunnel Addressing Protocol", draft-ietf-
ngtrans-isatap (work in progress), February 2004.

[LLMNR] Esibov, L., Aboba, B. and D. Thaler, "Linklocal Multicast
Name Resolution", draft-ietf-dnsext-mdns (work in progress), January

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2004.

[MECH] Gilligan, R. and E. Nordmark, "Basic Transition Mechanisms
for IPv6 Hosts and Routers", draft-ietf-v6ops-mech-v2 (work draft-ietf-v6ops-mech-v2, Work in
progress),
Progress, February 2003.

[NODEREQ] Loughney, J., "IPv6 Node Requirements", draft-ietf-ipv6-node-
requirements (work
requirements, Work in progress), Progress, October 2003.

[UNIQUE] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", draft-ietf-ipv6-unique-local-addr (work draft-ietf-ipv6-unique-local-addr, Work in progress), Progress,
January 2004.

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Informative References

[BCP0048]

[BCP48] Dawkins, S., Montenegro, G., Kojo, M. and V. Magret, "End-
to-end "End-to-
end Performance Implications of Slow Links", BCP 48, RFC 3150, July
2001.

[STD0013]

[STD13] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.

[RFC2402] Kent, S. and R. Atkinson, "IP Authentication Header", RFC
2402, November 1998.

[RFC2406] Kent, S. and R. Atkinson, "IP Encapsulating Security Payload
(ESP)", RFC 2406, November 1998.

[RFC2491] Armitage, G., Schulter, P., Jork, M. and G. Harter, "IPv6
over Non-Broadcast Multiple Access (NBMA) networks", RFC 2491,
January 1999.

[RFC2492] Armitage, G., Schulter, P. and M. Jork, "IPv6 over ATM
Networks", RFC 2492, January 1999.

[RFC2710] Deering, S., Fenner, W. and B. Haberman, "Multicast Listener
Discovery (MLD) for IPv6", RFC 2710, October 1999.

[RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via
IPv4 Clouds", RFC 3056, February 2001.

[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M.
Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC
3315, July 2003.

[ANYCAST] Hagino, J. and K. Ettikan, "An Analysis of IPv6 Anycast",
draft-ietf-ipngwg-ipv6-anycast-analysis (work
draft-ietf-ipngwg-ipv6-anycast-analysis, Work in progress), Progress, June

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Internet-Draft ISATAP February 2004 2003.

[DNSOPV6] Durand, A., Ihren, J., and Savola P., "Operational
Considerations and Issues with IPv6 DNS", draft-ietf-dnsop-ipv6-dns-
issues, work-in-progress, January 2004.

[FLOW] Rajahalme, J., Conta, A., Carpenter, B. and S. Deering,
"IPv6 Flow Label Specification", draft-ietf-ipv6-flow-label (work draft-ietf-ipv6-flow-label, Work in
progress),
Progress, December 2003.

[FRAG] Mogul, J. and C. Kent, "Fragmentation Considered Harmful", In
Proc. SIGCOMM '87 Workshop on Frontiers in Computer Communications
Technology. August, 1987.

[FTMIB] Haberman, B. and M. Wasserman, "IP Forwarding Table MIB",
draft-ietf-ipv6-rfc2096-update (work
draft-ietf-ipv6-rfc2096-update, Work in progress), Progress, August 2003.

[IPMIB] Routhier, S., "Management Information Base for the Internet
Protocol (IP)", draft-ietf-ipv6-rfc2011-update (work draft-ietf-ipv6-rfc2011-update, Work in progress), Progress,
September 2003.

[NIQUERY] Crawford, M., "IPv6 Node Information Queries", draft-ietf-
ipngwg-icmp-name-lookups (work in progress), June 2003.

[SEND] Arkko, J., Kempf, J., Sommerfield, B., Zill, B. and P.

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Nikander, "Secure Neighbor Discovery (SEND)", draft-ietf-send-ndopt
(work draft-ietf-send-ndopt,
Work in progress), Progress, October 2003.

[TCPMIB] Raghunarayan, R., "Management Information Base for the
Transmission Control Protocol (TCP)", draft-ietf-ipv6-rfc2012-update
(work

[SENDPS] Nikander, P., Kempf, J. and E. Nordmark, "IPv6 Neighbor
Discovery Trust Models and Threats", draft-ietf-send-psreq, Work in progress), November
Progress, October 2003.

[TUNMIB] Thaler, D., "IP Tunnel MIB", draft-ietf-ipv6-inet-tunnel-mib
(work draft-ietf-ipv6-inet-tunnel-mib,
Work in progress), Progress, January 2004.

[UDPMIB] Raghunarayan, R., "Management Information Base for the
Transmission Control Protocol (TCP)", draft-ietf-ipv6-rfc2012-update
(work in progress), November 2003.

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Authors' Addresses

Fred L. Templin
Nokia
313 Fairchild Drive
Mountain View, CA 94110
US

Phone: +1 650 625 2331
EMail: ftemplin@iprg.nokia.com

Tim Gleeson
Cisco Systems K.K.
Shinjuku Mitsu Building
2-1-1 Nishishinjuku, Shinjuku-ku
Tokyo 163-0409
Japan

EMail: tgleeson@cisco.com

Mohit Talwar
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052-6399
US

Phone: +1 425 705 3131
EMail: mohitt@microsoft.com

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Dave Thaler
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052-6399
US

Phone: +1 425 703 8835
EMail: dthaler@microsoft.com

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Intellectual Property Statement

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Full Copyright Statement

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except as needed for the purpose of developing Internet standards in

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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.

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The limited permissions granted above are perpetual and will not be
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Acknowledgment

Funding for the RFC Editor function is currently provided by the
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