WDIFF

draft-ietf-mpls-cr-ldp-00.txt --> draft-ietf-mpls-cr-ldp-01.txt

MPLS Working Group L. Andersson, A. Fredette, B. Jamoussi Bilel Jamoussi, Editor
Internet Draft Nortel Networks
Expiration Date: July August 1999

February 1999
R. Callon
IronBridge Networks

P. Doolan
Ennovate Networks

N. Feldman
IBM Corp

E. Gray
Lucent Technologies

J. Halpern
Newbridge Networks

J. Heinanen
Telia Finland

T. E. Kilty
Northchurch Communications

A. G. Malis
Ascend Communications, Inc.

M. Girish
SBC Technology Resources, Inc.

K. Sundell
Ericsson

P. Vaananen
Nokia Telecommunications

T. Worster
General DataComm, Inc.

L. Wu, R. Dantu
Alcatel

January 1998

Constraint-Based LSP Setup using LDP

draft-ietf-mpls-cr-ldp-00.txt

draft-ietf-mpls-cr-ldp-01.txt

Status of this Memo

This document is an Internet-Draft. Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.

Internet-Drafts are working

Jamoussi, et. al. January 26, 1999 [Page 1]

CR-LDP Specification - 2 - Exp. Apr 1999 documents of the Internet Engineering
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Distribution of this memo is unlimited.

Abstract

Label Distribution Protocol (LDP) is defined in [LDP] for
distribution of labels inside one MPLS domain. One of the most
important services that may be offered using MPLS in general and LDP
in particular is support for constraint-based routing of traffic
across the routed network. Constraint-based routing offers the
opportunity to extend the information used to setup paths beyond what
is available for the routing protocol. For instance, an LSP can be
setup based on an explicit route constraint, a Service Class (SC)
constraint, or both. constraints, QoS constraints, and
others. Constraint-based routing (CR) and is a mechanism used to meet
Traffic Engineering requirements that have been proposed by [FRAME],
[ARCH] and [TER]. These requirements may be met by extending LDP for
support of constraint-based routed label switched paths (CRLSPs).

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CR-LDP Specification - 2 - Exp. August 1999

Other uses exist for CRLSPs as well ([VPN1] ([VPN1], [VPN2] and [VPN2]). [VPN3]).

This draft specifies mechanisms and TLVs for support of CRLSPs using
LDP. The Explicit Route object and procedures are extracted from
[ER].

Table of Contents

1. Introduction

The need for constraint-based routing (CR) in MPLS has been explored
elsewhere [ARCH], [FRAME], ......................................... 3
2. Constraint-based Routing Overview .................... 3
2.1 Strict and [TER]. Loose Explicit routing is a subset
of the more general constraint-based routing function. At the MPLS WG
meeting held during the Washington IETF there was consensus that LDP
should support explicit routing of LSPs with provision for indication
of associated (forwarding) priority. In the Chicago meeting, the
decision was made that support for explicit path setup in LDP will be
moved to a separate document. This document provides that support. We
propose an end-to-end setup mechanism of a constraint-based routed
LSP (CRLSP) initiated by the ingress LSR. We also specify mechanisms
to provide means for reservation of resources for the explicitly
routed LSP.

We introduce TLVs Routes ..................... 4
2.2 Traffic Characteristics .............................. 4
2.3 Pre-emption .......................................... 5
2.4 Route Pinning ........................................ 5
2.5 Resource Class ....................................... 5
3. Solution Overview .................................... 5
3.1 Required Messages and procedures that provide support for: TLVs ........................... 7
3.2 Label Request Message ................................ 7
3.3 Label Mapping Message ................................ 8
3.4 Notification Message ................................. 9
3.5 Release & Withdraw Messages .......................... 9
4. Protocol Specification .............................. 9
4.1 Explicit Route TLV (ER-TLV) ......................... 10
4.2 Explicit Route Hop TLV .............................. 10
4.3 Traffic Parameters TLV .............................. 12
4.3.1 Semantics ........................................... 13
4.3.1.1 Frequency ........................................... 13
4.3.1.2 Peak Rate ........................................... 14
4.3.1.3 Committed Rate ...................................... 14
4.3.1.4 Excess Burst Size .................................... 14
4.3.1.5 Peak Rate Token Bucket................................ 14
4.3.1.6 Committed Data Rate Token Bucket ..................... 15
4.3.1.7 Weight ......................... ..................... 16
4.3.2 Procedures ........................................... 16
4.3.2.1 Label Request Message ................................ 16
4.3.2.2 Label Mapping Message ................................ 16
4.3.2.3 Notification Message ................................. 17
4.4 Preemption TLV ....................................... 18
4.5 LSPID TLV ........................................... 18
4.6 Resource Class TLV .................................. 19
4.7 ER-Hop Semantics ..................................... 19
4.7.1 ER-Hop 1 TLV IPv4 Prefix ............................. 20
4.7.2 ER-Hop 2 TLV IPv6 Prefix ............................. 20
4.7.3 ER-Hop 3 TLV AS Number ............................... 21
4.7.4 ER-Hop 4 TLV LSPID ................................... 21
4.8 Processing of the ER-TLV ............................. 22
4.8.1 Selection of the next hop ............................ 22
4.8.2 Adding the Label Request Message to the next hop ..... 24
4.9 Route Pinning TLV ................................... 24
4.10 CR-LSP FEC Element ................................... 24
4.11 Error Subcodes ...................................... 25

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CR-LDP Specification - 3 - Exp. Apr August 1999

5. Security Considerations .............................. 26
6. Acknowledgement ...................................... 26
7. References ........................................... 26
8. Author Information ................................... 28

Appendix A CRLSP Establishment Examples ......................... 30
A.1 Strict and Loose Explicit Routing
- Specification of Service Class
- Specification of Traffic Parameters
- Route Pinning
- CRLSP bumping though setup/holding priority
- Handling Failures

2. CRLSP Overview

CRLSP over LDP Specification is designed with several goals in mind:

1. Meet the requirements outlined in [TER] for performing traffic
engineering Example ........................ 30
A.2 Node Groups and provide a solid foundation for performing more
general constrain-based routing.

2. Build on already specified functionality that meets the
requirements whenever possible. Hence, this specifications is
based on [LDP] and the Explicit Route object and procedures
defined Specific Nodes Example ............... 31

Appendix B QoS Service Examples ................................. 34
B.1 Service Examples ..................................... 34
B.2 Establishing CR-LSP Supporting Real-Time Applications. 35
B.3 Establishing CR-LSP Delay Insensitive Applications ... 36

1. Introduction

The need for constraint-based routing (CR) in [ER].

3. Keep the solution simple MPLS has been explored
elsewhere [ARCH], [FRAME], and tractable.

In this document, support for unidirectional point-to-point CRLSPs is
specified. Support for point-to-multipoint, multipoint-to-point, [TER]. Explicit routing is
for further study (FFS).

Support for explicitly routed LSPs in this specification depends on a subset
of the following minimal LDP behaviors as specified in [LDP]:

- Basic and/or Extended Discovery Mechanisms.

- Use more general constraint-based routing function. At the Label Request Message defined in [LDP] in downstream on
demand label advertisement mode with ordered control.

- Use MPLS WG
meeting held during the Label Mapping Message defined in [LDP] in downstream on
demand mode Washington IETF there was consensus that LDP
should support explicit routing of LSPs with ordered control.

- Use provision for indication
of associated (forwarding) priority. In the Notification Message defined Chicago meeting, a
decision was made that support for explicit path setup in [LDP].

- Use the Withdraw LDP will be
moved to a separate document. This document provides that support and Release Messages defined
it has been accepted as a working document in [LDP].

- Loop detection (in the case of loosely routed segments Orlando meeting.
This specification proposes an end-to-end setup mechanism of a
CRLSP) mechanisms.

In addition,
constraint-based routed LSP (CRLSP) initiated by the following functionality is added ingress LSR. We
also specify mechanisms to what's defined
in [LDP]:

- The Label Request Message provide means for reservation of resources
using LDP.

This document introduce TLVs and procedures that provide support for:

- Strict and Loose Explicit Routing
- Specification of Traffic Parameters
- Route Pinning
- CRLSP Pre-emption though setup/holding priorities
- Handling Failures
- LSPID
- Resource Class

Section 2 introduces the various constraints defined in this
specification. Section 3 outlines the CR-LDP solution. Section 4
defines the TLVs and procedures used to setup constraint-based routed
label switched paths. Appendix A provides several examples of CR-LSP
path setup. Appendix B provides Service Definition Examples.

2. Constraint-based Routing Overview

Constraint-based routing is a CRLSP includes a CR-
TLV based on mechanism that supports the path vector Traffic
Engineering requirements defined in [ER] and specified in
Section 4 [TER]. Explicit Routing is a
subset of this document. the more general constraint-based routing where the

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CR-LDP Specification - 4 - Exp. Apr August 1999

- An LSR implicitly infers ordered control from

constraint is the existence of explicit route (ER). Other constraints are defined
to provide a
CR-TLV in network operator with control over the Label Request Message. path taken by an
LSP. This means that the LSR can
still be configured for independent control for LSPs established
as a result section is an overview of dynamic routing. However, when a Label Request
Message includes the various constraints supported
by this specification.

2.1 Strict and Loose Explicit Routes

Like any other LSP an CRLSP is a CR TLV, then ordered control path through an MPLS network. The
difference is used to that while other paths are setup solely based on
information in routing tables or from a management system, the CRLSP. Note that this
constraint-based route is also true for calculated at one point at the loosely routed
parts edge of a CRLSP.

- Traffic Parameters TLVs may optionally be carried in the Label
Request Message
network based on criteria, including but not limited to specify the CRLSP traffic characteristics.

- New status codes are defined routing
information. The intention is that this functionality shall give
desired special characteristics to handle error notification for
failure of established paths specified in the CR-TLV.

Examples of CRLSP establishment are given LSP in Appendix A order to illustrate
how better support
the mechanisms described in this draft work.

3. Required Messages and TLVs

Any Messages, TLVs, and procedures not defined explicitly in this
document are defined in traffic sent over the [LDP] Specification. LSP. The following
subsections are meant as a cross reference reason for setting up CRLSPs,
might be that one wants to assign certain bandwidth or other Service
Class characteristics to the [LDP] document and
indication of additional functionality beyond what's defined LSP, or that one wants to make sure that
alternative routes use physically separate paths through the network.

An explicit route is represented in [LDP]
where necessary.

3.1 Label Request Message

The a Label Request Message is as defined in 3.5.8 a
list of [LDP] with nodes or groups of nodes along the
following modifications (required only if constraint-based route.
When the CR-TLV CRLSP is included in established, all or a subset of the Label Request Message):

- Only nodes in a single FEC-TLV
group may be included in the Label Request
Message.

- The Optional Parameters TLV includes traversed by the definition of LSP. Certain operations to be
performed along the
Constraint-based TLV specified path can also be encoded in Section 4 and the Traffic
Parameters TLV specified in Section 5.

- constraint-based
route.

The Procedures capability to handle the Label Request are augmented specify, in addition to specified nodes, groups of
nodes, of which a subset will be traversed by the
procedures CRLSP, allows the
system a significant amount of local flexibility in fulfilling a
request for processing a constraint-based route. This allows the generator of
the CR-TLV as defined in Section 4.

- The Procedures constraint-based route to handle Service Classes are defined in Section
5.

3.2 Label Mapping Message have some degree of imperfect
information about the details of the path.

The Label Mapping Message constraint-based route is encoded as defined a series of ER-Hops
contained in 3.5.7 a constraint-based route TLV. Each ER-Hop may identify
a group of [LDP] nodes in the constraint-based route. A constraint-based
route is then a path including all of the identified groups of nodes.

To simplify the discussion, we call each group of nodes an abstract
node. Thus, we can also say that a constraint-based route is a path
including all of the abstract nodes, with the
following modifications:

- Only specified operations
occurring along that path.

2.2 Traffic Characteristics

The traffic characteristics of a single Label-TLV may be included path are described in the Label Mapping
Message. Traffic
Parameters TLV in terms of a peak rate, committed rate, and service
granularity. The peak and committed rates describe the bandwidth
constraints of a path while the service granularity can be used to
specify a constraint on the delay variation that the CRLDP MPLS
domain may introduce to a path's traffic.

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CR-LDP Specification - 5 - Exp. Apr August 1999

- The FEC-Label Mapping TLV does not include any of

2.3 Pre-emption

CR-LDP signals the optional
TLVs.

- The Label Mapping Message Procedures are limited to downstream resources required by a path on demand ordered control mode each hop of mapping.

A Mapping message is transmitted by the
route. If a downstream LSR route with sufficient resources can not be found,
existing paths may be rerouted to reallocate resources to an upstream
LSR under one of the following conditions:

1. The LSR new
path. This is the egress end process of the CRLSP path pre-emption. Setup and holding
priorities are used to rank existing paths (holding priority) and the
new path (setup priority) to determine if the new path can pre-empt
an upstream mapping
has been requested.

2. existing path.

The LSR received setupPriority of a mapping from its downstream next hop LSR for
an new CRLSP for which an upstream request is still pending.

3.3. Notification Message

The Notification message is as defined in Section 3.5.1 of [LDP] and the Status TLV encoding is as defined in Section 3.4.7 of [LDP].

Establishment of an Explicitly Routed LSP may fail for a variety holdingPriority attributes
of
reasons. All such failures are considered advisory conditions and
they are signaled by the Notification Message.

Notification messages carry Status TLVs to specify events being
signaled. New status codes existing CRLSP are defined in Section 4.8.3 used to signal
error notifications associated with the establishment of specify priorities. Signaling a CRLSP and
higher holding priority expresses that the processing path, once it has been
established, should have a lower chance of being pre-empted.
Signaling a higher setup priority expresses the CR-TLV.

4. Constraint-based Routing TLV

Label Request Messages defined expectation that, in [LDP] optionally carry
the
Constraint-based Routing TLV (CR-TLV) based on case that resource are unavailable, the path vector
defined in [ER] and described in this section is more likely to
pre-empt other paths. The exact rules determining bumping are an
aspect of the specification. network policy.

The inclusion allocation of the CR TLV in the Label Request Message indicates
the path setup and holding priority values to be taken in the paths is an
aspect of network even if normal routing indicates
otherwise. policy.

The format of the CR-TLV is described below.

4.1 CR-TLV setup and holding priority values range from zero (0) to seven
(7). The CR-TLV value zero (0) is an object that specifies the path priority assigned to be taken by the
LSP being established. In addition, the CR-TLV may also include the most
important path. It is referred to as the Service Class (SC) constraints associated with highest priority. Seven (7)
is the LSP, a setup
and a holding priority used for path bumping, and the least important path. The use of default
priority values is an aspect of network policy.

The setupPriority of a CRLSP should not be higher (numerically less)
than its holdingPriority since it might bump an LSP and be bumped by
next "equivalent" request.

2.4 Route Pinning

Route pinning
request flag. Reserved bits in the CR-TLV allow for the
specification is applicable to segments of other an LSP attributes in that are loosely
routed - i.e. those segments which are specified with a next hop with
the future. If 'L' bit set or where the reserved
bits are exhausted, additional TLVs next hop is an "abstract node". A CRLSP
may be specified setup using route pinning if it is undesirable to allow for change the
indication of other
path used by an LSP attributes during because a better next hop becomes available at
some LSR along the loosely routed portion of the LSP.

2.5 Resource Class

Network resources may be classified in various ways by the network
operator. These classes are also known as "colors" or "administrative
groups". When an CR-LSP is being established, it's necessary to
indicate which resource classes the CR-LSP can draw from.

3. Solution Overview

CRLSP setup. over LDP Specification is designed with the following goals:

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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| CR-TLV (0x0800) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Reserved | SC |P| Hp | Sp |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-Hop TLV 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-Hop TLV 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ............ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-Hop TLV n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit

Unknown TLV bit. Upon receipt of an unknown TLV, if clear (=0), a
notification must be returned to

1. Meet the message originator requirements outlined in [TER] for performing traffic
engineering and provide a solid foundation for performing more
general constraint-based routing.

2. Build on already specified functionality that meets the
entire message must be ignored; if set (=1), the unknown TLV
requirements whenever possible. Hence, this specifications is
silently ignored
based on [LDP] and the rest of the message is processed as if the
unknown TLV did not exist.

F bit

Forward unknown TLV bit. This bit only applies when the U bit is set Explicit Route object and procedures
defined in [ER].

3. Keep the LDP message containing the unknown TLV solution simple.

In this document, support for unidirectional point-to-point CRLSPs is to be forwarded.
If clear (=0), the unknown TLV
specified. Support for point-to-multipoint, multipoint-to-point, is not forwarded with
for further study (FFS).

Support for constraint-based routed LSPs in this specification
depends on the containing
message; if set (=1), following minimal LDP behaviors as specified in [LDP]:

- Basic and/or Extended Discovery Mechanisms.

- Use the unknown TLV is forwarded Label Request Message defined in [LDP] in downstream on
demand label advertisement mode with ordered control.

- Use the
containing message.

Type

A two byte field carrying Label Mapping Message defined in [LDP] in downstream on
demand mode with ordered control.

- Use the value Notification Message defined in [LDP].

- Use the Withdraw and Release Messages defined in [LDP].

- Use the Loop Detection (in the case of loosely routed segments
of a CRLSP) mechanisms defined in [LDP].

In addition, the CR-TLV type which following functionality is
0x800.

Length

Specifies added to what's defined
in [LDP]:

- The Label Request Message used to setup a CRLSP includes one or
more CR-TLVs defined in Section 4. For instance, the length of Label Request
Message may include the value field ER-TLV.

- An LSR implicitly infers ordered control from the existence of
one or more CR-TLVs in bytes.

Reserved the Label Request Message. This field is reserved. It must means that
the LSR can still be set configured for independent control for LSPs
established as a result of dynamic routing. However, when a Label
Request Message includes one or more of the CR-TLVs, then ordered
control is used to zero on transmission and
must be ignored on receipt. We expect setup the CRLSP. Note that this is also true
for the loosely routed parts of a CRLSP.

- New status codes are defined to use these fields handle error notification for
carrying information that support other constrain-based routing
information.

P bit
failure of established paths specified in the CR-TLV.

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CR-LDP Specification - 7 - Exp. Apr August 1999

When set indicates that the loosely routed segments must remain
pinned-down.

Examples of CRLSP must be rerouted only when adjacency is lost
along the segment. When not set, it indicates that the loose segment
is not pinned down and must be changed establishment are given in Appendix A to match illustrate
how the underlying hop-
by-hop path.

The SC Field is used to specify the Service Class of the CRLSP. This
field allows for the definition of up to 8 different Service Classes.
Currently, Three Service Classes are defined: Best Effort (0),
Throughput Sensitive (1), mechanisms described in this draft work.

3.1 Required Messages and Delay Sensitive (2) Service Classes.
These SCs TLVs

Any Messages, TLVs, and procedures not defined explicitly in this
document are further defined in Section 5.

A SetupPriority of value zero (0) is the priority assigned [LDP] Specification. The state
transitions which relate to CR-LDP messages can be found in [LDP-
STATE].

The following subsections are meant as a cross reference to the
most important path. It [LDP]
document and indication of additional functionality beyond what's
defined in [LDP] where necessary.

3.2 Label Request Message

The Label Request Message is referred to as defined in 3.5.8 of [LDP] with the highest priority. Four
(4)
following modifications (required only if any of the CR-TLVs is
included in the priority for Label Request Message):

- Only a single FEC-TLV may be included in the least important path. Label Request
Message. The higher the
setup priority, the more paths CR-LDP can bump to set up the path. CR-LSP FEC TLV should be used.

- The default value is 2. Values 5, 6, and 7 are reserved.

A HoldingPriority of value zero (0) Return Message ID TLV is MANDATORY.

- The Optional Parameters TLV includes the priority assigned to definition of any of
the
most important path. It is referred Constraint-based TLVs specified in Section 4.

- The Procedures to as handle the highest priority. Four
(4) is Label Request Message are augmented
by the priority procedures for processing of the least important path. CR-TLVs as defined in
Section 4.

The higher the
holding priority, the less likely it is encoding for the CR-LDP to reallocate its
bandwidth to a new path. The default value is 2. Values 5, 6, and 7
are reserved.

4.1.1 Setup and holding priorities

CR-LDP signals the resources required by a path on each hop of the
route. If a route with sufficient resources can not be found,
existing paths may be rerouted to reallocate resources to the new
path. This is the process of bumping paths. Setup and holding
priorities are used to rank existing paths (holding priority) and the
new path (setup priority) to determine if the new path can bump an
existing path.

The setupPriority of a new CRLSP and the holdingPriority attributes
of the existing CRLSP are used to specify these priorities. The
higher the holding priority, the less likely it is for CR-LDP to
reallocate its bandwidth to a new path. Similarly, the higher the
setup priority, the more paths CR-LDP can bump to set up the path.

The setup and holding priority values range from zero (0) to four
(4). The value zero (0) is the priority assigned to the most
important path. It Label Request Message is referred to as the highest priority. Four (4)
is the priority for the least important path. The default values for follows:

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CR-LDP Specification - 8 - Exp. Apr August 1999

both setup and holding priority should be 2. By setting the default
value of both setup and holding priorities at the middle of the
range, all connections are initially treated the same. However, when
network operators see a need for the use of path bumping, the values
of setup and holding priorities can be gracefully adjusted up or down
from the middle of the range.

An existing path can be bumped if and only if the setupPriority of
the new path is numerically less than the holdingPriority of the
existing path.

To illustrate the use of the setup and holding priority, consider a
network which supports two service types (e.g., video and data
services). The video traffic is given a low setup priority because
new video paths can use an alternate public network if the primary
network cannot accommodate the new path. However, the video traffic
is given a high holding priority since it is undesirable for the path
to be rerouted during an active LSP. For data traffic, high setup and
holding priorities are desirable since data paths cannot be
established on an alternate network.

The setup and holding priorities can be different to allow setup at
one priority and holding at an independent priority. This would allow
some calls not to invoke bumping and not to be bumped at the same
time.

The setupPriority of a CRLSP should not be higher (numerically less)
than its holdingPriority since it might bump an LSP and be bumped by
next "equivalent" request.

Bumping by default only happens as a last resort when there are no
routes available for a given path.

During the instantiation of a path that must bump other paths, lower
holding priority paths are bumped before higher priority paths. The
decision as to which of the available paths are bumped at each
intermediate node by the new path is arbitrary.

4.2 ER-Hop TLV

The contents of a constraint-based route TLV are a series of variable
length ER-Hop TLVs. Each ER-Hop TLV has the form:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------//--------------+
|L| Type 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U| Label Request (0x0401) | Message Length | Contents
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------//--------------+

Jamoussi, et. al. January 26, 1999 [Page 8]

CR-LDP Specification - 9 - Exp. Apr 1999 Message ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FEC TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Return Message ID TLV (mandatory) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSPID TLV (CR-LDP, mandatory) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Pinning TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Resource Class TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Pre-emption TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.3 Label Mapping Message

The L bit Label Mapping Message is an attribute as defined in 3.5.7 of [LDP] with the ER-Hop. The L bit is set if the
ER-Hop represents
following modifications:

- Only a loose hop single Label-TLV may be included in the explicit route. If the bit Label Mapping
Message.

- The Label Mapping Message MUST include Label Request Message ID
TLV.

- The Label Mapping Message MUST include LSPID TLV.

- The Label Mapping Message Procedures are limited to downstream
on demand ordered control mode.

A Mapping message is
not set, the ER-Hop represents transmitted by a strict hop in the explicit route.

Type

A seven-bit field indicating the type of contents downstream LSR to an upstream
LSR under one of the ER-Hop.
Currently defined values are:

Value Type
----- ------------------------
0 Reserved
1 IPv4 prefix
2 IPv6 prefix
32 Autonomous system number

Length following conditions:

1. The Length field contains LSR is the total length egress end of the ER-Hop in bytes. It
includes the L bit, Type CRLSP and Length fields. an upstream mapping
has been requested.

2. The length must always be LSR received a multiple of 4, and at least 4.

Contents

A variable length field containing the node or abstract node that mapping from its downstream next hop LSR for
an CRLSP for which an upstream request is still pending.

The encoding for the consecutive nodes that make up the explicit routed LSP.

4.3 Applicability CR-LDP Label Mapping Message is as follows:

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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U| Label Mapping (0x0400) | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FEC TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Request Message ID TLV (mandatory) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSPID TLV (CR-LDP, mandatory) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.4 Notification Message

The CR-TLV Notification Message is as defined in this version Section 3.5.1 of [LDP] and
the specification Status TLV encoding is intended for
unicast only. CRLSPs for multicast are FFS.

4.4 Semantics as defined in Section 3.4.7 of [LDP].

Establishment of the CR-TLV

Like any other LSP an CRLSP is a path through Explicitly Routed LSP may fail for a network. The
difference is that while other paths variety of
reasons. All such failures are setup solely based on
information in routing tables or from a management system, the
constraint-based route is calculated at one point at considered advisory conditions and
they are signaled by the edge of
network based on criteria, including but not limited to routing
information. The intention is that this functionality shall give
desired special characteristics Notification Message.

Notification Messages carry Status TLVs to the LSP specify events being
signaled. New status codes are defined in order Section 4.11 to better support signal
error notifications associated with the traffic sent over establishment of a CRLSP and
the LSP. processing of the CR-TLV.

The reason for setting up CRLSPs,
might be that one wants to assign certain bandwidth or other Service
Class characteristics to Notification Message must carry the LSP, or that one wants to make sure that
alternative routes use physically separate paths through LSPID TLV of the network.

A CRLSP is represented
corresponding CRLSP.

3.5 Release and Withdraw Messages

The Label Release and Label Withdraw Messages are used as specified
in a [LDP] to clear CR-LSPs. These message may also carry the LSPID
TLV.

4. Protocol Specification

The Label Request Message as a list of nodes Messages defined in [LDP] optionally carries one or groups
more of nodes along the constraint-based route. When optional Constraint-based Routing TLVs (CR-TLVs) defined
in this section. If needed, other constraints can be supported later
through the CRLSP
is established, all or a subset definition of new TLVs. In this specification, the nodes in a group may be
following TLVs are defined:

- Explicit Route TLV

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traversed by the LSP. Certain operations to be performed along

- Explicit Route Hop TLV
- Traffic Parameters TLV
- Preemption TLV
- LSPID TLV
- Route Pinning TLV
- Resource Class TLV
- CRLSP FEC TLV

4.1 Explicit Route TLV (ER-TLV)

The ER-TLV is an object that specifies the path can also be encoded in the constraint-based route.

The capability to specify, in addition to specified nodes, groups of
nodes, of which a subset will be traversed taken by the CRLSP, allows the
system a significant amount
LSP being established. It is composed of local flexibility one or more Explicit Route
Hop TLVs (ER-Hop TLVs) defined in fulfilling a
request for a constraint-based route. This allows the generator of
the constraint-based route to have some degree of imperfect
information about the details of the path.

The constraint-based route is encoded as a series of ER-Hops
contained in a constraint-based route TLV. Each Section 4.2.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| ER-TLV (0x0800) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-Hop may identify
a group of nodes in the constraint-based route. A constraint-based
route is then a path including all of the identified groups of nodes.

To simplify the discussion, we call each group of nodes an abstract
node. Thus, we can also say that a constraint-based route is a path
including all of the abstract nodes, with the specified operations
occurring along that path.

4.5 Strict and Loose ER-Hops

The L TLV 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-Hop TLV 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ............ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-Hop TLV n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in the ER-Hop is a one-bit attribute. If the L [LDP].

F bit is set,
then
Forward unknown TLV bit. As defined in [LDP].

Type
A two byte field carrying the value of the attribute ER-TLV type which
is "loose." Otherwise, 0x800.

Length
Specifies the value length of the attribute is "strict." For brevity, we say that if the value of
the field in bytes.

ER-Hop attribute is loose then it is a "loose ER-Hop."
Otherwise, it's a "strict ER-Hop." Further, we say that the abstract
node of a strict TLVs
One or loose more ER-Hop is a strict or a loose node,
respectively. Loose and strict nodes are always interpreted relative
to their prior abstract nodes.

The path between a strict node and its prior node MUST include only
network nodes from the strict node and its prior abstract node.

The path between a loose node and its prior node MAY include other
network nodes which are not part of the strict node or its prior
abstract node.

4.6 Loops

While the constraint-based route TLV is of finite length, the
existence of loose nodes implies that it is possible to construct
forwarding loops during transients in the underlying routing
protocol. This may be detected by the originator of the constraint-
based route through the use a path vector object as TLVs defined in [LDP].

4.7 ER-Hop semantics

4.7.1. ER-Hop 1: The IPv4 prefix Section 4.2.

4.2 Explicit Route Hop TLV (ER-Hop TLV)

The contents of an IPv4 prefix ER-Hop ER-TLV are a 4 byte IPv4 address, 1 series of variable length ER-Hop
TLVs. Each ER-Hop TLV has the form:

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byte of prefix length, and 1 byte of padding. The abstract node
represented by this ER-Hop is the set of nodes which have an IP
address which lies within this prefix. Note that a prefix length of
32 indicates a single IPv4 node.

The length of the IPv4 prefix ER-Hop is 8 bytes. The contents of the
1 byte of padding must be zero on transmission and must not be
checked on receipt.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type
|U|F| ER-Hop-Type | Length | IPv4 Address (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Content // | IPv4 Address (Continued) | Prefix |0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

ER-Hop Type

IPv4 Address 0x01

Length
A one byte fourteen-bit field indicating the total type of contents of
the ER-Hop. Currently defined values are:

Value Type
----- ------------------------
0x801 IPv4 prefix
0x802 IPv6 prefix
0x803 Autonomous system number
0x804 LSPID

Length
Specifies the length of the TLV value field in bytes. It
includes

L bit
The L bit is an attribute of the ER-Hop. The L bit is set if the L-bit,
ER-Hop represents a loose hop in the Type, Length, explicit route. If the IP Address, and bit is
not set, the Prefix
fields. ER-Hop represents a strict hop in the explicit route.

The length L bit in the ER-Hop is always 8 bytes.

IP Address

A four byte field indicating a one-bit attribute. If the L bit is
set, then the value of the attribute is "loose." Otherwise, the
value of the attribute is "strict." For brevity, we say that if
the value of the IP Address.

Prefix Length

1-32

Padding

Zero on transmission. Ignored on receipt.

4.7.2. ER-Hop 2: attribute is loose then it is a "loose
ER-Hop." Otherwise, it's a "strict ER-Hop." Further, we say that
the abstract node of a strict or loose ER-Hop is a strict or a
loose node, respectively. Loose and strict nodes are always
interpreted relative to their prior abstract nodes.

The IPv6 address path between a strict node and its prior node MUST include
only network nodes from the strict node and its prior abstract
node.

The path between a loose node and its prior node MAY include other
network nodes which are not part of the strict node or its prior
abstract node.

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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | IPV6 address (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) | Prefix |0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type

0x02 IPv6 address

Length

The Length contains the total

Contents
A variable length of the ER-Hop TLV in bytes,
including field containing the Type and Length fields. The Length node or abstract node that
is always 20.

IPv6 address

A 128-bit unicast host address.

Prefix Length

1-128

Padding

Zero on transmission. Ignored on receipt.

4.7.3. ER-Hop 32: the consecutive nodes that make up the explicit routed LSP.

4.3 Traffic Parameters TLV

The autonomous system number following sections describe the CRLSP Traffic Parameters. The contents
required characteristics of an autonomous system (AS) number ER-Hop are a 2 byte
autonomous system number. The abstract node represented CRLSP are expressed by this ER-
Hop is the set of nodes belonging Traffic
Parameter values.

A Traffic Parameters TLV, is used to signal the autonomous system. Traffic Parameter
values. The length of Traffic Parameters are defined in the AS number ER-Hop subsequent
sections.

The Traffic Parameters TLV contains a Flags field, a Frequency, a
Weight, and the five Traffic Parameters PDR, PBS, CDR, CBS, EBS. The
Traffic Parameters TLV is 4 bytes. shown below:

Type

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AS Number 0x20

Length

A one byte field indicating the total length of the TLV in bytes. It
includes the L-bit, the Type, and Length, and the AS number fields.
The length is always 4 bytes.

AS number
| Peak Data Rate (PDR) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peak Burst Size (PBS) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Committed Data Rate (CDR) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Committed Burst Size (CBS) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Excess Burst Size (EBS) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

Type
A two byte fourteen-bit field indicating the AS number.

4.8. Processing of carrying the Constraint-Based Route TLV

4.8.1. Selection value of the next hop

A Label Request message containing a constraint-based route TLV must
determine the next hop for this path. Selection of this next hop may
involve a selection from a set of possible alternatives. The
mechanism for making a selection from this set is implementation
dependent and ER-TLV type which
is outside of 0x810.

Length
Specifies the scope of this specification.
Selection of particular paths is also outside length of the scope of this
specification, but it value field in bytes.

Flags
The Flags field is assumed that each node will make a best
effort attempt shown below:

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+--+--+--+--+--+--+--+--+
| Res |F6|F5|F4|F3|F2|F1|
+--+--+--+--+--+--+--+--+

Res - These bits are reserved.
Zero on transmission.
Ignored on receipt.
F1 - Corresponds to determine a loop-free path. Note that such best
efforts may be overridden by local policy.

To determine the next hop for PDR.
F2 - Corresponds to the path, a node performs PBS.
F3 - Corresponds to the following
steps:

1) The node receiving CDR.
F4 - Corresponds to the Label Request message must first
evaluate CBS.
F5 - Corresponds to the first ER-Hop. If EBS.
F6 - Corresponds to the L bit Weight.

Each flag Fi is not set in the first
ER-Hop a Negotiable Flag corresponding to a Traffic
Parameter. The Negotiable Flag value zero denotes NotNegotiable
and if the node is not part of the abstract node described
by the first ER-Hop, it has received the message in error, and
should return a "Bad initial ER-Hop" error. If value one denotes Negotiable.

Frequency
The Frequency field is coded as an 8 bit unsigned integer with
the L following code points defined:

0 - Unspecified
1 - Frequent
2 - VeryFrequest
3-255 - Reserved

Reserved
Zero on transmission. Ignored on receipt.

Weight
An 8 bit is set
and unsigned integer indicating the local node is not part weight of the abstract node described by
the first ER-Hop, the node selects a next hop CRLSP.
Valid weight values are from 1 to 255. The value 0 means
that weight is along the
path to the abstract node described by not applicable for the first ER-Hop. If there CRLSP.

Traffic Parameters
Each Traffic Parameter is no first ER-Hop, the message encoded as a 32 bit IEEE single-
precision floating point number. A value of positive infinity is also in error
represented as an IEEE single-precision floating-point number with
an exponent of all ones (255) and the system
should return a "Bad Constraint-Based Routing TLV" error.

2) If there is no second ER-Hop, this indicates the end sign and mantissa of the
constraint-based route. all
zeros. The constraint-based route TLV should values PDR and CDR are in units of bytes per second.
The values PBS, CBS and EBS are in units of bytes.

The value of PDR MUST be
removed from the Label Request message. This node may greater than or may not
be equal to the end value of the LSP. Processing continues with section 4.8.2,
where CDR
in a new constraint-based route TLV may be added to correctly encoded Traffic Parameters TLV.

4.3.1 Semantics

4.3.1.1 Frequency

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The Frequency specifies at what granularity the Label
Request message.

3) If CDR allocated to the node
CRLSP is also a part of made available. The value VeryFrequently means that the abstract node described by
available rate should average at least the second ER-Hop, then CDR when measured over any
time interval equal to or longer than the node deletes shortest packet time at the first ER-Hop and
continues processing with step 2, above. Note
CDR. The value Frequently means that this makes the
second ER-Hop into available rate should
average at least the first ER-Hop CDR when measured over any time interval equal
to or longer than a small number of shortest packet times at the next iteration.

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4) CDR.
The node determines if it is topologically adjacent to the
abstract node described by value Unspecified means that the second ER-Hop. If so, CDR MAY be provided at any
granularity.

4.3.1.2 Peak Rate

The Peak Rate defines the node
selects a particular next hop maximum rate at which traffic SHOULD be
sent to the CRLSP. The Peak Rate is a member useful for the purpose of
resource allocation. If resource allocation within the abstract
node. The node then deletes MPLS domain
depends on the first ER-Hop and continues
processing with section 4.8.2.

5) Next, Peak Rate value then it should be enforced at the node selects a next hop within
ingress to the abstract node MPLS domain.

The Peak Rate is defined in terms of the first ER-Hop two Traffic Parameters PDR
and PBS, see section 4.3.1.5 below.

4.3.1.3 Committed Rate

The Committed Rate defines the rate that is along the path MPLS domain commits to
be available to the abstract node CRLSP.

The Committed Rate is defined in terms of the second ER-Hop. If no such path exists then there are two
cases:

5a) If the second ER-Hop is a strict ER-Hop, then there is an
error Traffic Parameters
CDR and CBS, see section 4.3.1.6 below.

4.3.1.4 Excess Burst Size

The Excess Burst Size may be used at the node should return a "Bad strict node" error.

5b) Otherwise, if the second ER-Hop is a loose ER-Hop, then the
node selects any next hop that is along edge of an MPLS domain for
the path purpose of traffic conditioning. The EBS MAY be used to measure
the next
abstract node. If no path exists, then there is an error, and extent by which the
node should return traffic sent on a "Bad loose node" error.

6) Finally, CRLSP exceeds the node replaces committed
rate.

The possible traffic conditioning actions, such as passing, marking
or dropping, are specific to the first ER-Hop MPLS domain.

The Excess Burst Size is defined together with any ER-Hop
that denotes an abstract node containing the next hop. This Committed Rate,
see section 4.3.1.6 below.

4.3.1.5 Peak Rate Token Bucket

The Peak Rate of a CRLSP is
necessary so that when specified in terms of a token bucket P
with token rate PDR and maximum token bucket size PBS.

The token bucket P is initially (at time 0) full, i.e., the token
count Tp(0) = PBS. Thereafter, the constraint-based route token count Tp, if less than PBS,
is received incremented by
the next hop, it will be accepted.

7) Progress the Label Request Message to the next hop.

4.8.2. Adding ER-Hops to the constraint-based route TLV

After selecting one PDR times per second. When a next hop, the node may alter the constraint-based
route in packet of size B
bytes arrives at time t, the following ways.

If, as part of executing happens:

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o If Tp(t)-B >= 0, the algorithm packet is not in section 4.8.1, excess of the
constraint-based route TLV peak
rate and Tp is removed, decremented by B down to the node may add a new
constraint-based route TLV.

Otherwise, if minimum value
of 0, else

o the node packet is a member in excess of the abstract node for the first
ER-Hop, then peak rate and Tp is
not decremented.

Note that according to the above definition, a series positive infinite
value of ER-Hops may either PDR or PBS implies that arriving packets are never in
excess of the peak rate.

The actual implementation of a LSR doesn't need to be inserted before modeled
according to the first
ER-Hop or may replace above formal token bucket specification.

4.3.1.6 Committed Data Rate Token Bucket

The committed rate of a CRLSP is specified in terms of a token bucket
C with rate CDR. The extent by which the first ER-Hop. Each ER-Hop offered rate exceeds the
committed rate MAY be measured in this series
must denote an abstract node that terms of another token bucket E,
which also operates at rate CDR. The maximum size of the token
bucket C is CBS and the maximum size of the token bucket E is EBS.

The token buckets C and E are initially (at time 0) full, i.e., the
token count Tc(0) = CBS and the token count Te(0) = EBS. Thereafter,
the token counts Tc and Te are updated CDR times per second as
follows:

o If Tc is less than CBS, Tc is incremented by one, else

o if Te is less then EBS, Te is incremented by one, else

o neither Tc nor Te is incremented.

When a subset packet of size B bytes arrives at time t, the current abstract
node.

Alternately, following
happens:

o If Tc(t)-B >= 0, the packet is not in excess of the Committed
Rate and Tc is decremented
by B down to the minimum value of 0, else

o if Te(t)-B >= 0, the packet is in excess of the Committed Rate
but is not in excess of the EBS and Te is
decremented by B down to the minimum value of 0, else

o the packet is in excess of both the Committed Rate and the EBS
and neither Tc nor Tc is decremented.

Note that according to the above specification, a CDR value of
positive infinity implies that arriving packets are never in excess
of either the Committed Rate or EBS. A positive infinite value of
either CBS or EBS implies that the respective limit cannot be

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exceeded.

The actual implementation of a LSR doesn't need to be modeled
according to the above formal specification.

4.3.1.7 Weight

The weight determines the CRLSP's relative share of the possible
excess bandwidth above its committed rate. The definition of
"relative share" is MPLS domain specific.

4.3.2 Procedures

4.3.2.1 Label Request Message

If an LSR receives an incorrectly encoded Traffic Parameters TLV in
which the value of PDR is less than the value of CDR then it MUST
send a Notification Message including the Status code Traffic
Parameters Unavailable to the upstream LSR from which it received the
erroneous message.

If a Traffic Parameter is indicated as Negotiable in the Label
Request Message by the corresponding Negotiable Flag then an LSR MAY
replace the Traffic Parameter value with a smaller value.

If the Weight is indicated as Negotiable in the Label Request Message
by the corresponding Negotiable Flag then an LSR may adjust replace
the Weight value with a lower value (down to 1).

If, after possible Traffic Parameter negotiation, an LSR can support
the CRLSP Traffic Parameters then the LSR MUST reserve the
corresponding resources for the CRLSP.

If, after possible Traffic Parameter negotiation, an LSR cannot
support the CRLSP Traffic Parameters then the LSR MUST send a
notification message that contains the Resource Unavailable status
code.

4.3.2.2 Label Mapping Message

If an LSR receives an incorrectly encoded Traffic Parameters TLV in
which the value of PDR is less than the value of CDR then it MUST
send a Label Release message containing the Status code Traffic
Parameters Unavailable to the LSR from which it received the
erroneous message.

The egress LSR MUST include the (possibly negotiated) Traffic
Parameters and Weight in the Label Mapping message.

The Traffic Parameters and the Weight in a Label Mapping message MUST
be forwarded unchanged.

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An LSR SHOULD adjust the resources that it reserved for a CRLSP when
it receives a Label Mapping Message if the Traffic Parameters differ
from those in the corresponding Label Request Message.

4.3.2.3 Notification Message

If an LSR receives a Notification Message for a CRLSP, it SHOULD
release any resources that it possibly had reserved for the CRLSP.

In addition, on receiving a Notification Message from a Downstream
LSR that is associated with a Label Request from an upstream LSR, the
local LSR MUST propagate the Notification message using the
procedures in [LDP].

4.4 Preemption TLV

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| Preemption-TLV (0x0820) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SetPrio | HoldPrio | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

Type
A fourteen-bit field carrying the value of the Preemption-TLV
type which is 0x810.

Length
Specifies the length of the value field in bytes.

Reserved
Zero on transmission. Ignored on receipt.

SetPrio
A SetupPriority of value zero (0) is the priority assigned to the
most important path. It is referred to as the highest priority.
Seven (7) is the priority for the least important path. The higher
the setup priority, the more paths CR-LDP can bump to set up the
path.

HoldPrio
A HoldingPriority of value zero (0) is the priority assigned to
the most important path. It is referred to as the highest
priority. Seven (7) is the priority for the least important path.

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The higher the holding priority, the less likely it is for CR-LDP
to reallocate its bandwidth to a new path.

4.5 LSPID TLV

LSPID is a unique identifier of a CRLSP within an MPLS network.

The LSPID is composed of the ingress LSR Router ID and a Locally
unique CRLSP ID to that LSR.

The LSPID is useful in network management, in CR-LSP repair, and in
using an already established CR-LSP as a hop in an ER-TLV.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| LSPID-TLV (0x0821) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Local CRLSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ingress LSR Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

Type
A fourteen-bit field carrying the value of the LSPID-TLV
type which is 0x821.

Length
Specifies the length of the value field in bytes.

Reserved
Zero on transmission. Ignored on receipt.

Local CRLSP ID
The Local LSP ID is an identifier of the CRLSP locally unique
within the Ingress LSR originating the CRLDP.

Ingress LSR Router ID
A 4 byte field indicating the Ingress LSR ID.

4.6 Resource Class (Color) TLV

The Resource Class as defined in [TER] is used to specify which links
are acceptable by this CRLSP. This information allows for the

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networks topology to be pruned.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| ResCls-TLV (0x0822) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RsCls |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

Type
A fourteen-bit field carrying the value of the ResCls-TLV
type which is 0x822.

Length
Specifies the length of the value field in bytes.

RsCls
The Resource Class bit mask indicating which of the
32 "administrative groups" or "colors" of links
the CRLSP can traverse.

4.7 ER-Hop semantics

4.7.1. ER-Hop 1: The IPv4 prefix

The abstract node represented by this ER-Hop is the set of nodes
which have an IP address which lies within this prefix. Note that a
prefix length of 32 indicates a single IPv4 node.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| 0x801 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserved | PreLen |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

Jamoussi, et. al. February 25, 1999 [Page 19]

CR-LDP Specification - 20 - Exp. August 1999

Type
IPv4 Address 0x801

Length
Specifies the length of the value field in bytes.

L Bit
Set to indicate Loose hop.
Cleared to indicate a strict hop.

Reserved
Zero on transmission. Ignored on receipt.

PreLen
Prefix Length 1-32

IP Address
A four byte field indicating the IP Address.

4.7.2. ER-Hop 2: The IPv6 address

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| 0x802 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserved | PreLen |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

Type
0x802 IPv6 address

Length
Specifies the first ER-Hop is a loose ER-Hop, an arbitrary
series length of ER-Hops may be inserted prior to the first ER-Hop.

4.8.3. Error subcodes

In the processing described above, certain errors need value field in bytes.

L Bit
Set to be reported
as part of the Notification message. This section defines the status
codes for the errors described above. indicate Loose hop.

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CR-LDP Specification - 15 21 - Exp. Apr August 1999

Status Code Type
-------------------------------------- ----------
Bad Constraint-Based Routing TLV Error 0x04000001
Bad Strict Node Error 0x04000002
Bad Loose Node Error 0x04000003
Bad Initial

Cleared to indicate a strict hop.

Reserved
Zero on transmission. Ignored on receipt.

PreLen
Prefix Length 1-128

IPv6 address
A 128-bit unicast host address.

4.7.3. ER-Hop Error 0x04000004
Resource Unavailable 0x04000005
Service Class Unavailable 0x04000006
Traffic Parameters Unavailable 0x04000007

5.0 CRLSP Service Classes and Traffic Parameters 32: The following sections describe autonomous system number

The abstract node represented by this ER-Hop is the CRLSP Service Classes (SCs), and
their associated traffic parameters. set of nodes
belonging to the autonomous system.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| 0x803 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserved | AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

Type
AS Number 0x803

Length
Specifies the length of the value field in bytes.

L Bit
Set to indicate Loose hop.
Cleared to indicate a strict hop.

Reserved
Zero on transmission. Ignored on receipt.

AS Number
Autonomous System number

4.7.4. ER-Hop 4: LSPID

The CRLSP Service Class LSPID is signaled used to identify the tunnel ingress point as the next
hop in the SC Field of ER. This ER-Hop allows for stacking new CR-LSPs within an
already established CR-LSP. It also allows for splicing the CR-TLV CR-LSP

Jamoussi, et. al. February 25, 1999 [Page 21]

CR-LDP Specification - 22 - Exp. August 1999

being established with an existing CR-LSP.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| 0x804 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserved | Local LSPID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ingress LSR Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in Section 4.1.

Three Service Classes are currently supported by CR-LDP:

Service Class Value
-------------------------- -----
Best Effort (BE) 0x0
Throughput Sensitive (TS) 0x1
Delay Sensitive (DS) 0x2

These service classes are specified [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

Type
LSPID 0x804

Length
Specifies the following sections.

5.1 Best Effort (BE)

The request length of the BE SC implies that there are no expected service
guarantees from the network. The service provided by the network is value field in bytes.

L Bit
Set to indicate Loose hop.
Cleared to indicate a strict hop.

Reserved
Zero on transmission. Ignored on receipt.

Local LSPID
A 2 byte field indicating the familiar best effort service.

The Peak Date Rate (PDR) LSPID which is the only traffic parameter that may be
specified unique
with the BE SC. The specification of the PDR allows the
network reference to perform traffic shaping and policing functions.

5.2 Throughput Sensitive (TS)

In the service model for its Ingress LSR.

Ingress LSR Router ID
A 4 byte field indicating the Ingress LSR ID.

4.8. Processing of the Throughput Sensitive SC, Explicit Route TLV

4.8.1. Selection of the network
commits to deliver with high probability user datagrams at next hop

A Label Request Message containing a rate explicit route TLV must
determine the next hop for this path. Selection of
at least CDR (Committed Data Rate). The user this next hop may transmit at
involve a rate
higher than CDR but datagrams in excess of CDR would have selection from a lower
probability set of being delivered. If the user sends at possible alternatives. The
mechanism for making a rate selection from this set is implementation
dependent and is outside of CDR or
lower the network commits to deliver with high probability all the
user datagrams.

The TS SC has an associated tolerance to scope of this specification.
Selection of particular paths is also outside of the burstiness scope of arriving this
specification, but it is assumed that each node will make a best
effort attempt to determine a loop-free path. Note that such best

Jamoussi, et. al. January 26, February 25, 1999 [Page 15] 22]

CR-LDP Specification - 16 23 - Exp. Apr August 1999

user datagrams. This tolerance is defined

efforts may be overridden by local policy.

To determine the traffic parameter
Committed Burst Tolerance (CBT).

Ideally, a TS CRLSP request carries with it next hop for the path, a rich set of three
traffic parameters (PDR, CDR, and CBT) that accurately describe its
traffic characteristics. This allows node performs the network to perform resource
reservation, traffic shaping, and traffic policing.

However, for following
steps:

1) The node receiving the sake of simplicity of Label Request Message must first
evaluate the service definition, first ER-Hop. If the
CDR L bit is not set in the only parameter that MUST always be specified for a TS
CRLSP. A peak data rate parameter (PDR) first
ER-Hop and a CBT are optional
traffic parameters for if the TS SC.

The network should make every effort to preserve ordering node is not part of the
delivered datagrams of a TS CRLSP.

Network traffic that requires a low packet loss ratio at abstract node described
by the first ER-Hop, it has received the message in error, and
should return a given CDR
but "Bad initial ER-Hop" error. If the L bit is not particularly sensitive to delay set
and jitter (e.g., network
control traffic) is suited to the TS SC. The selection local node is not part of the TS SC
is used to signal to abstract node described by
the various nodes along first ER-Hop, the path node selects a next hop that is along the
queuing and scheduling mechanisms used
path to handle the CRLSP should
provide a low packet loss ratio.

5.3 Delay Sensitive (DS)

In abstract node described by the service model for first ER-Hop. If there
is no first ER-Hop, the Delay Sensitive SC, message is also in error and the network commits
to deliver with high probability user datagrams at system
should return a rate "Bad Explicit Routing TLV" error.

2) If there is no second ER-Hop, this indicates the end of CDR
(Committed Data Rate) with minimum delay and delay variation. the
explicit route. The
user MUST transmit data at a rate of CDR or lower in order to explicit route TLV should be
eligible for DS service. Datagrams in excess of CDR removed from the
Label Request Message. This node may or may not be discarded
by the network. If the user sends at a rate end of CDR or lower the
network commits to deliver with high probability all user datagrams
LSP. Processing continues with low delay and delay variation. If the user sends at section 4.8.2, where a rate
higher than CDR the network does not provide any guarantees on the
excess traffic.

The Delay Sensitive SC has an associated tolerance new
explicit route TLV may be added to the burstiness
of arriving user datagrams. This tolerance is defined by Label Request Message.

3) If the traffic
parameter Committed Burst Tolerance (CBT).

Ideally, a DS CRLSP request carries with it node is also a rich set part of three
traffic parameters (PDR, CDR, and CBT) that accurately describe its
traffic characteristics. This allows the network to perform resource
reservation, traffic shaping and policing.

However, for the sake of simplicity of abstract node described by
the service definition, second ER-Hop, then the
CDR is node deletes the only parameter that MUST always be specified for a DS
CRLSP. A peak data rate parameter (PDR) first ER-Hop and a CBT are optional
traffic parameters for
continues processing with step 2, above. Note that this makes the DS SC.

The network should make every effort to preserve ordering of
second ER-Hop into the

Jamoussi, et. al. January 26, 1999 [Page 16]

CR-LDP Specification - 17 - Exp. Apr 1999

delivered datagrams first ER-Hop of a DS CRLSP.

Network traffic that requires a low delay and delay variation at a
given CDR (e.g., voice traffic) is suited to the DS SC. next iteration.

4) The selection
of the DS SC node determines if it is used to signal topologically adjacent to the various nodes along the path
that
abstract node described by the queuing and scheduling mechanisms used to handle second ER-Hop. If so, the CRLSP
should provide low delay and delay variation.

5.4 Traffic Parameters

The CRLSP traffic parameters are defined in this section.

The traffic parameters CDR, CBT and PDR are defined in terms of node
selects a
TOKEN_BUCKET_TSPEC as specified in [RFC2215]. The following mapping particular next hop which is a member of parameters in the TOKEN_BUCKET_TSPEC is used:

Token rate, r = CDR
Bucket depth, b = CBT
Peak traffic rate, p = PDR
Minimum policed unit, m = 1
Maximum packet size, M = MTU abstract
node. The Traffic Parameters TLV node then deletes the first ER-Hop and continues
processing with section 4.8.2.

5) Next, the node selects a next hop within the abstract node of
the first ER-Hop that is used along the path to signal the traffic
characteristics abstract node of
the CRLSP. These traffic parameters are used to
perform functions second ER-Hop. If no such as resource reservation, Shaping, path exists then there are two
cases:

5a) If the second ER-Hop is a strict ER-Hop, then there is an
error and
Policing. See [SIN] for more details. The encoding for the Traffic
Parameters TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| Traffic TLV (0x0810) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PDR TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CDR TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CBT TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5.4.1 Peak data rate (PDR) TLV

The value of traffic parameter PDR node should return a "Bad strict node" error.

5b) Otherwise, if the second ER-Hop is given as a positive integer in
bytes per second. Zero loose ER-Hop, then the
node selects any next hop that is not along the path to the next
abstract node. If no path exists within the MPLS domain, then
there is an error, and the node should return a valid value of PDR.

The user may specify "Bad loose node"
error.

6) Finally, the value of PDR depending node replaces the SC of first ER-Hop with any ER-Hop
that denotes an abstract node containing the CRLSP.
Specifying next hop. This is
necessary so that when the PDR allows explicit route is received by the network to use traffic management
functions such as shaping. next
hop, it will be accepted.

Jamoussi, et. al. January 26, February 25, 1999 [Page 17] 23]

CR-LDP Specification - 18 24 - Exp. Apr August 1999

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| PDR

7) Progress the Label Request Message to the next hop.

4.8.2. Adding ER-Hops to the explicit route TLV (0x0811) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PDR in Bytes/sec |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5.4.2. Committed Data Rate (CDR)

The value of traffic parameter CDR is given as a positive integer in
bytes per second. Zero is not

After selecting a valid value of CDR.

The user next hop, the node may provide a requested value of CDR in alter the CRLSP request
depending on explicit route in
the SC following ways.

If, as part of executing the CRLSP.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| CDR TLV (0x0812) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CDR algorithm in Bytes/sec |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5.4.3. Committed Burst Tolerance (CBT)

The value of traffic parameter CBT section 4.8.1, the explicit
route TLV is given in bytes. Zero removed, the node may add a new explicit route TLV.

Otherwise, if the node is not a
valid value of CBT.

The requested value member of CBT MUST be no smaller than the MTU abstract node for the first
ER-Hop, then a series of ER-Hops may be inserted before the
originating interface.

The user first
ER-Hop or may provide replace the first ER-Hop. Each ER-Hop in this series
must denote an abstract node that is a requested value subset of CBT in the CRLSP request.
If current abstract
node.

Alternately, if the user chooses not to specify first ER-Hop is a requested value loose ER-Hop, an arbitrary
series of CBT and the
network is policing the traffic, then any excess traffic will ER-Hops may be
dropped by inserted prior to the network. first ER-Hop.

4.9 Route Pinning TLV

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| CBT TLV (0x0813) 0x823 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CBT in Bytes
|P| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

6. Open Issues

This section captures the issues that need further study.

Jamoussi, et. al. January 26, 1999 [Page 18]

CR-LDP Specification - 19 - Exp. Apr 1999

1) Review the FSM described

U bit
Unknown TLV bit. As defined in Appendix B and extend it by the CR-TLV
processing [LDP].

F bit
Forward unknown TLV bit. As defined in Sections 4.8.1 and 4.8.2.

2) Consider if all three traffic parameters have to be signaled at
all times and if the network should supply default values for the
missing parameters.

3) Consider the following extensions to [LDP].

Type
Pinning-TLV type 0x823

Length
Specifies the CR-TLV:

3.1) Changing length of the 'P' bit to "next hop flag" and making it a 2-bit
wide value field with the following values:

- 00 "local repair", which means if it belongs to a loosely
routed segment, and the LSR detects a next hop change, the LSR
will try in bytes.

P Bit
The P bit is set to establish a new LSP from this point on and switch
it over 1 to the new LSP when it indicate that route pinning is setup.

- 01 "global repair", which means when the LSR detects a next
hop change, the LSR will tear down the LSP, the ingress LSR
will try requested.
The P bit is set to reestablish another LSP through the new path.

- 10 "pinned", which means that the loosely routed segments
must remain pinned down.

- 11 Reserved.

3.2) Adding one more field "LSPID" before ER-Hop TLV. LSPID can
be used 0 to identify a network wide unique CRLSP. indicate that route pinning is not
requested

Reserved
Zero on transmission. Ignored on receipt.

4.10 CRLSP FEC Element

Jamoussi, et. al. February 25, 1999 [Page 24]

CR-LDP Specification - The first 4 bytes carrying the ingress LSR IP address 25 - The second 4 bytes carrying the unique ID value assigned by
the ingress LSR.

4) Consider the following extension Exp. August 1999

A new FEC element is introduced in this specification to the ER-Hop TLV:

For support CR-
LSPs. The CRLDP FEC Element is an opaque FEC.

FEC Element Type field, add one more type, LSPID, which means the current Value
type name

CRLSP will go through another 0x04 No value; i.e., 0 value octets;
see below.

CRLSP which FEC Element
To be used only in Messages of CR-LSPs.

The CR-LSP FEC TLV encoding is identified with this
LSPID value:

Value Type
----- -----
4 LSPID

Extend processing the LSPID ER-Hop as follows: If the

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| FEC(0x0100) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CR-LSP (4) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

U bit
Unknown TLV bit. As defined in [LDP].

F bit
Forward unknown TLV bit. As defined in [LDP].

Type
FEC TLV type of ER-
Hop is LSPID, and 0x0100

Length
Specifies the other end of this CRLSP is not part length of the
constraint-based route TLV, add it value field in bytes.

CR-LSP FEC Element Type
0x04

Reserved
Zero on transmission. Ignored on receipt.

4.11 Error subcodes

In the processing described above, certain errors need to be reported
as part of the constraint-based TLV
with L bit turned off.

5) Consider traffic parameter negotiation and Notification Message. This section defines the ability to change status
codes for the traffic parameters associated with an already established path errors described in this specification.

Jamoussi, et. al. January 26, February 25, 1999 [Page 19] 25]

CR-LDP Specification - 20 26 - Exp. Apr August 1999

without tearing the old path down.

Status Code Type
-------------------------------------- ----------
Bad Explicit Routing TLV Error 0x04000001
Bad Strict Node Error 0x04000002
Bad Loose Node Error 0x04000003
Bad Initial ER-Hop Error 0x04000004
Resource Unavailable 0x04000005
Traffic Parameters Unavailable 0x04000006
Setup abort 0x04000007

5. Security

No security issues are discussed in this version of

Pre-emption has to be controlled by the draft.

8. MPLS domain.

Resource reservation requires the LSRs to have an LSP admission
control function.

Normal routing can be bypassed by Traffic Engineered LSPs.

6. Acknowledgments

The messages used to signal the CRLSP setup are based on the work
done by the [LDP] team. The Explicit Route object and procedures used
in this specification are based on [ER].

The authors would also like to acknowledge the careful review and
comments of Osama Aboul-Magd, Ken Hayward, Greg Wright, Geetha Brown, Brian Williams, Peter Ashwood-smith,
Paul Beaubien, Matthew Yuen, Liam Casey, and Ankur Anand.

7. References

[FRAME] Callon

[LDP] Andersson et al, "Framework for Multiprotocol Label Switching", "Label Distribution Protocol Specification"
work in progress (draft-ietf-mpls-framework-02), November 1997. (draft-ietf-mpls-ldp-03), Feb. 1999.

[ARCH] Rosen et al, "Multiprotocol Label Switching Architecture",
work in progress (draft-ietf-mpls-arch-02), July 1998.

[LDP] Andersson (draft-ietf-mpls-arch-04), Feb. 1999.

[FRAME] Callon et al, "Label Distribution Protocol Specification" "Framework for Multiprotocol Label Switching",
work in progress (draft-ietf-mpls-ldp-02.txt), (draft-ietf-mpls-framework-02), November
1997.

[TER] Awduche et al, "Requirements for Traffic Engineering Over
MPLS", work in progress (draft-ietf-mpls-traffic-eng-00),
August 1998.

[ER] Guerin et al, "Setting up Reservations on Explicit Paths
using RSVP", work in progress (draft-guerin-expl-path-rsvp-01.txt, (draft-guerin-expl-path-rsvp-
01)
November 1997.

[TER] Awduche et al, "Requirements for Traffic Engineering Over
MPLS", work in progress (draft-awduche-mpls-traffic-eng-00), April
1998.

Jamoussi, et. al. February 25, 1999 [Page 26]

CR-LDP Specification - 27 - Exp. August 1999

[VPN1] Heinanen et al, "MPLS Mappings of Generic VPN Mechanisms",
work in progress (draft-heinanen-generic-vpn-mpls-00),
August 1998.

[VPN2] Jamieson et al, "MPLS VPN Architecture" work in progress
(draft-jamieson-mpls-vpn-00), August 1998.

[RFC2215] S. Shenker and J. Wroclawski, General Characterization
Parameters for Integrated Service Network Elements, RFC 2215, Sep
1997.

[SIN] B. Jamoussi, N. Feldman, and L. Andersson, "MPLS Ships

[VPN3] T. Li, "CPE based VPNs using MPLS", work in the
Night with ATM", (draft-jamoussi-mpls-sin-00.txt), August progress (draft-
li-mpls-vpn-00.txt), October 1998.

[LDP-STATE] L. Wu, et. al., "LDP State Machine" work in progress
(draft-ietf-mpls-ldp-state-00), Feb 1999.

Jamoussi, et. al. January 26, February 25, 1999 [Page 20] 27]

CR-LDP Specification - 21 28 - Exp. Apr August 1999

10.

8. Author Information

Osama S. Aboul-Magd Loa Andersson
Nortel Networks Director Bay Architecture Lab, EMEA Lab,EMEA
P O Box 3511 Station C Kungsgatan 34, PO Box 1788
Ottawa, ON K1Y 4H7 111 97 Stockholm, Sweden
Canada phone: +46 8 441 78 34
phone: +1 613 763-5827 mobile +46 70 522 78 34
e-mail:
osama@NortelNetworks.com loa_andersson@baynetworks.com

Peter Ashwood-Smith Ross Callon
Nortel Networks IronBridge Networks
P O Box 3511 Station C 55 Hayden Avenue,
Ottawa, ON K1Y 4H7 Lexington, MA 02173
Canada Phone: +1-781-402-8017
Email:
phone: +1 613 763-4534 rcallon@ironbridgenetworks.com
petera@NortelNetworks.com

Ram Dantu Paul Doolan
Alcatel USA Inc. Ennovate Networks
IP Competence Center 330 Codman Hill Rd
1201 E. Campbell Road.,446-315 Marlborough MA 01719
Richadson, TX USA., 75081-2206 Phone: 978-263-2002
Phone: 972 996 2938 pdoolan@ennovatenetworks.com
Fax: 972 996 5902
Email: ram.dantu@aud.alcatel.com

Paul Doolan
Ennovate Networks
330 Codman Hill Rd
Marlborough MA 01719
Phone: 978-263-2002
email: pdoolan@ennovatenetworks.com 996 5902
ram.dantu@aud.alcatel.com

Nancy Feldman Andre Fredette
IBM Corp. Nortel Networks
17 Skyline Drive
Hawthorne NY 10532
Phone: 914-784-3254
email: nkf@us.ibm.com

Andre Fredette
Nortel Networks 3 Federal Street
Hawthorne NY 10532 Billerica, MA 01821
email:
Phone: 914-784-3254 fredette@baynetworks.com
nkf@us.ibm.com

Eric Gray Joel M. Halpern
Lucent Technologies, Inc Newbridge Networks Inc.
1600 Osgood St. 593 Herndon Parkway
North Andover, MA 01847
email: ewgray@lucent.com

Jamoussi, et. al. January 26, 1999 [Page 21]

CR-LDP Specification - 22 - Exp. Apr 1999

Joel M. Halpern
Newbridge Networks Inc.
593 Herndon Parkway Herndon, VA 20170
email: jhalpern@newbridge.com
Phone: 603-659-3386 phone: 1-703-736-5954
fax: 1-703-736-5959
ewgray@lucent.com jhalpern@newbridge.com

Juha Heinanen Fiffi Hellstrand
Telia Finland, Inc. Ericsson Telecom AB
Myyrmaentie 2 S-126 25 STOCKHOLM
01600 VANTAA Sweden
Finland Tel: +46 8 719 4933
Tel: +358 303 944 808
Email: 41 500 4808 etxfiff@etxb.ericsson.se
jh@telia.fi

Jamoussi, et. al. February 25, 1999 [Page 28]

CR-LDP Specification - 29 - Exp. August 1999

Bilel Jamoussi Timothy E. Kilty
Nortel Networks Northchurch Communications
P O Box 3511 Station C 5 Corporate Drive,
Ottawa, ON K1Y 4H7
Canada
phone: +1 613 765-4814
email: jamoussi@NortelNetworks.com

Timothy E. Kilty
Northchurch Communications
5 Corporate Drive, Andover, MA 018110
Canada phone: 978 691-4656
Email:
phone: +1 613 765-4814 tkilty@northc.com
jamoussi@NortelNetworks.com

Andrew G. Malis
Ascend Communications, Inc.
1 Robbins Road
Westford, MA 01886
phone: 978 952-7414
fax: 978 392-2074
Email: malis@ascend.com Muckai K Girish
Ascend Communications, Inc. SBC Technology Resources, Inc.
1 Robbins Road 4698 Willow Road
Westford, MA 01886 Pleasanton, CA 94588
phone: 978 952-7414 Phone: (925) 598-1263
fax: 978 392-2074 Fax: (925) 598-1321
Email:
malis@ascend.com mgirish@tri.sbc.com

Kenneth Sundell
Ericsson
SE-126 25 Stockholm
Sweden

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email: kenneth.sundell@etx.ericsson.se Pasi Vaananen
Ericsson Nokia Telecommunications
SE-126 25 Stockholm 3 Burlington Woods Drive, Suite 250
Sweden Burlington, MA 01803
kenneth.sundell@etx.ericsson.se Phone: +1-781-238-4981
Email:
pasi.vaananen@ntc.nokia.com

Tom Worster Liwen Wu
General DataComm, Inc. Alcatel U.S.A
5 Mount Royal Ave.
Marlboro MA 01752
Email: tom.worster@gdc.com

Liwen Wu
Alcatel U.S.A 44983 Knoll Square
Marlboro MA 01752 Ashburn, Va. 20147
tom.worster@gdc.com USA
Phone: (703) 724-2619
FAX: (703) 724-2005
Inet:
liwen.wu@adn.alcatel.com

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Appendix A: CRLSP Establishment Examples

A.1 Strict Constraint-Based Explicit Route Example

This appendix provides an example for the setup of a strictly routed
CRLSP. In this example, each abstract node is represented by a
specific node.

The sample network used here is a four node network with two edge
LSRs and two core LSRs as follows:

a b c
LSR1------LSR2------LSR3------LSR4

LSR1 generates a Label Request Message as described in Section 3.1 of
this draft and sends it to LSR2. This message includes the CR-TLV.

The CR-TLV ER-TLV is composed by a vector of three ER-Hop TLVs <a, b, c>.
The ER-Hop TLVs used in this example are of type 0x01 0x0801 (IPv4 prefix)
with a prefix length of 32. Hence, each ER-Hop TLV identifies a
specific node as opposed to a group of nodes.

At LSR2, the following processing of the CR-TLV ER-TLV per Section 4.8.1 of
this draft takes place:

1) The first hop <a> is part of the abstract node LSR2. Therefore,
the first step passes the test. Go to step 2.

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2) There is a second ER-Hop, . Go to step 3.

3) LSR2 is not part of the abstract node described by the second
ER-Hop . Go to Step 4.

4) LSR2 determines that it is topologically adjacent to the
abstract node described by the second ER-Hop . LSR2 selects a
next hop (LSR3) which is the abstract node. LSR2 deletes the first
ER-Hop <a> from the CR-TLV ER-TLV which now becomes . Go to
Section 4.8.2.

At LSR2, the following processing of Section 4.8.2 takes place:

Executing algorithm 4.8.1 did not result in the removal of the
CR-TLV.
ER-TLV.

Also, LSR2 is not a member of the abstract node described by the
first ER-Hop .

Finally, the first ER-Hop is a strict hop.

Therefore, processing section 4.8.2 does not result in the
insertion of new ER-Hops. The selection of the next hop has been

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already done is step 4 of Section 4.8.1 and the processing of the
CR-TLV
ER-TLV is completed at LSR2. In this case, the Label Request
Message including the CR-TLV ER-TLV <b, c> is progressed by LSR2 to LSR3.

At LSR3, a similar processing to the CR-TLV ER-TLV takes place except that
the incoming CR-TLV ER-TLV = <b, c> and the outgoing CR-TLV ER-TLV is <c>.

At LSR4, the following processing of section 4.8.1 takes place:

1) The first hop <c> is part of the abstract node LSR4. Therefore,
the first step passes the test. Go to step 2.

2) There is no second ER-Hop, this indicates the end of the CRLSP.
The CR-TLV ER-TLV is removed from the Label Request Message. Processing
continues with Section 4.8.2.

At LSR4, the following processing of Section 4.8.2 takes place:

Executing algorithm 4.8.1 resulted in the removal of the CR-TLV. ER-TLV.
LSR4 does not add a new CR-TLV. ER-TLV.

Therefore, processing section 4.8.2 does not result in the
insertion of new ER-Hops. This indicates the end of the CRLSP and
the processing of the CR-TLV ER-TLV is completed at LSR4.

At LSR4, processing of Section 3.2 is invoked. The first condition is
satisfied (LSR4 is the egress end of the CRLSP and upstream mapping
has been requested). Therefore, a Label Mapping Message is generated

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CR-LDP Specification - 25 - Exp. Apr 1999
by LSR4 and sent to LSR3.

At LSR3, the processing of Section 3.2 is invoked. The second
condition is satisfied (LSR3 received a mapping from its downstream
next hop LSR4 for a CRLSP for which an upstream request is still
pending). Therefore, a Label Mapping Message is generated by LSR3 and
sent to LSR2.

At LSR2, a similar processing to LSR 3 takes place and a Label
Mapping Message is sent back to LSR1 which completes the end-to-end
CRLSP setup.

A.2. Node Groups and Specific Nodes Example

A request at an ingress LSR to setup a CRLSP might originate from a
management system or an application, the details are implementation
specific.

The ingress LSR uses information provided by the management system or
the application and possibly also information from the routing
database to calculated the constraint-based explicit route and to create the Label
Request Message.

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The Label request message carries together with other necessary
information a CR-TLV ER-TLV defining the constraint-based explicitly routed path. In our
example the list of hops in the ER-Hop TLV is supposed to contain an
abstract node representing a group of nodes, an abstract node
representing a specific node, another abstract node representing a
group of nodes, and an abstract node representing a specific egress
point.

In--{Group 1}--{Specific A}--{Group 2}--{Specific Out: B}

The CR-TLV ER-TLV contains four ER-Hop TLVs:

1. An ER-Hop TLV that specifies a group of LSR valid for the first
abstract node representing a group of nodes (Group 1).

2. An ER-Hop TLV that indicates the specific node (Node A).

3. An ER-Hop TLV that specifies a group of LSRs valid for the
second abstract node representing a group of nodes (Group 2).

4. An ER-Hop TLV that indicates the specific egress point for the
CRLSP (Node B).

All the ER-Hop TLVs are strictly routed nodes.

The setup procedure for this CRLSP works as follows:

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1. The ingress node sends the Label Request Message to a node that
is a member the group of nodes indicated in the first ER-Hop TLV,
following normal routing for the specific node (A).

2. The node that receives the message identifies itself as part of
the group indicated in the first ER-Hop TLV, and that it is not
the specific node (A) in the second. Further it realizes that the
specific node (A) is not one of its next hops.

3. It keeps the ER-Hop TLVs intact and sends a Label Request
Message to a node that is part of the group indicated in the first
ER-Hop TLV (Group 1), following normal routing for the specific
node (A).

4. The node that receives the message identifies itself as part of
the group indicated in the first ER-Hop TLV, and that it is not
the specific node (A) in the second ER-Hop TLV. Further it
realizes that the specific node (A) is one of its next hops.

5. It removes the first ER-Hop TLVs and sends a Label Request
Message to the specific node (A).

6. The specific node (A) recognizes itself in the first ER-Hop
TLV. Removes the specific ER-Hop TLV.

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7. It sends a Label Request message Message to a node that is a member of
the group (Group 2) indicated in the ER-Hop TLV.

8. The node that receives the message identifies itself as part of
the group indicated in the first ER-Hop TLV, further it realizes
that the specific egress node (B) is one of its next hops.

9. It sends a Label Request message Message to the specific egress node
(B).

10. The specific egress node (B) recognizes itself as the egress
for the CRLSP, it returns a Label Mapping Message, that will
traverse the same path as the Label Request Message in the
opposite direction.

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Appendix B. CR-LDP Finite State Machine

In this description of the CR-LDP FSM, behavior relating to the
state of LDP messages is assumed to be defined (implicitly or
explicitly) in [LDP]. In particular, LDP is assumed to retain
state information relating a Label Request made of a downstream
neighbor to the Label Request message(s) of upstream neighbors
(downstream-on-demand mode) which the (downstream) Label Request
is meant to satisfy. This will be true of many potential
applications of LDP, of which CR-LDP is an example. Minimally,
this state should include message IDs of Label Requests (both sent
and received) and the LSR(s) from which pending Label Request(s)
were received.

The FSM describes CR-LDP behavior in the following operations:

- Start of CRLSP setup (in which a Label Request is sent);

- Processing the CR-TLV portion of Label Requests;

- Completion of CRLSP setup (via Label Mapping messages);

- Notification of originator when:

- a loop is detected in a loose constraint-based route segment,

- an ER-Hop is not reachable from a previous ER-Hop,

- a next ER-Hop is strict and not directly connected to the
current LSR or

- the current LSR is strict and is not (part of the abstract
node in) the first ER-Hop in the CR-TLV;

- Withdrawing a CRLSP.

For the description, the following pictorial representations may be
used as an aid to understanding:

LSR 1 LSR 2 ... LSR n

.-----. .-----. .-----.
| ER | | ER | | ER |
`-----' `-----' `-----'
| CR-TLV CR-TLV ^ | CR-TLV CR-TLV ^
| Next | | Next |
| Hop | | Hop |
V | V |
.-----. Label .-----. Label as the Label .-----.
| LDP |----------->| LDP |-------> ... ------->| LDP |
`-----' Request `-----' Request Request `-----' Message in the
opposite direction.

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CRLSP Setup propagation

LSR 1 LSR 2 ... LSR n

.-----. .-----. .-----.
| ER | | ER | | ER |
`-----' `-----' `-----'
^ Status Status |
| Previous |
| Hop |
| V
.-----. Label .-----. Label Label .-----.
| LDP |<-----------| LDP |<------- ... <-------| LDP |
`-----' Mapping `-----' Mapping Mapping `-----'

CRLSP Status propagation

.---------------.
| ER | .---------------.
| Link/Call | | LDP |
| Admission | | |
| Control | | Label |
`---------------' | Allocation |
`---------------'

Related Tasks

B.1. CR-LDP Primitives

The following sections describe

Appendix B. QoS Service Examples

B.1 Service Examples

Construction of an end-to-end service is the logical interactions between
Constrain-based Route and LDP state machines in terms result of
primitives the rules
enforced at the edge and the treatment that describe packets receive at the minimal information exchange
required. These assume an asynchronous exchange model involving
locally significant IDs
network nodes. The rules define the traffic conditioning actions that is used
are implemented at the edge and they include policing with pass,
mark, and drop capabilities. The edge rules are expected to tie status be
defined by the mutual agreements between the service providers and
their customers and they will constitute an essential part of the
SLA. Therefore edge rules are not included in the signaling protocol.

Packets treatment at a request network node is usually referred to as the initial setup and to allow LDP to relate incoming/outgoing
Label Request messages. A synchronous model - possibly based on
multiple threads -
local behavior. Local behavior could be specified in many ways. One
example for local behavior specification is also possible the service frequency
introduced in section 4.3.2.1., together with the resource
reservation rules implemented at the nodes.

Edge rules and would eliminate local behaviors can be viewed as the need main building
blocks for IDs.

B.1.1. CR to LDP Primitives

LDP_SEND_REQ( TLV_List, To_LSR, Identifier )

TLV_List

TLVs to be sent to a neighboring LSR; includes at least an the end-to-end service construction. The following table
illustrates the applicability of the building block approach for
constructing different services including those defined for ATM.

Service PDR PBS CDR CBS EBS Service Conditioning
Examples Frequency Action
---------------------------------------------------------------------------

DS S S =PDR =PBS 0 Frequent drop>PDR

TS S S S S 0 Unspecified drop>PDR,PBS
mark>CDR,CBS

BE inf inf inf inf 0 Unspecified -

FRS S S CIR ~B_C ~B_E Unspecified drop>PDR,PBS
mark>CDR,CBS,EBS

ATM-CBR PCR CDVT =PCR =CDVT 0 VeryFrequent drop>PCR

ATM-VBR.3(rt) PCR CDVT SCR MBS 0 Frequent drop>PCR
mark>SCR,MBS

ATM-VBR.3(nrt) PCR CDVT SCR MBS 0 Unspecified drop>PCR
mark>SCR,MBS

ATM-UBR PCR CDVT - - 0 Unspecified drop>PCR

ATM-GFR.1 PCR CDVT MCR MBS 0 Unspecified drop>PCR

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CR-TLV and may contain additional TLVs (i.e. QoS TLVs).

To_LSR

The neighbor LSR

ATM-GFR.2 PCR CDVT MCR MBS 0 Unspecified drop>PCR
mark>MCR,MFS

int-serv-CL p m r b 0 Frequent drop>p
drop>r,b

S= User specified

In the above table, the DS refers to which a Label Request is delay sensitive service where
the network commits to deliver with high probability user datagrams
at a rate of PDR with minimum delay and delay requirements. Datagrams
in excess of PDR will be sent.

Identifier

Locally significant unique identifier. May be used discarded.

The TS refers to
associate a generic throughput sensitive service where the Label Request
network commit to be sent either deliver with high probability user datagrams at a Label
Request that was previously received (e.g. - LSR 2 above)
or
rate of at least CDR. The user may transmit at a subsequent CRLSP Status (e.g. - LSR 1 above).

LDP_SEND_RSP( Status, Identifier )

Status

Status rate higher than CDR
but datagrams in excess of CDR would have a specific CRLSP Setup Request. A Status lower probability of zero
indicates success; other Status values
being delivered.

The BE is the best effort service and it implies that there are given in Error
Subcodes section. This Status no
expected service guarantees from the network.

B.2. Establishing CR-LSP Supporting Real-Time Applications

In this scenario the customer needs to establish an LSP for
supporting real-time applications such voice and video. The Delay-
sensitive (DS) service is carried requested in Label Mapping or
Notification messages to this case.

The first step is the originator specification of the CRLSP setup.

Identifier

Locally significant unique identifier used to associate traffic parameters in the
Label Mapping
signaling message. The two parameters of interest to the DS service
are the PDR and the PBS and their values are specified by the user
based on his requirements. Since all the traffic parameters are
included in the signaling message, appropriate values must be sent with a Label Request received (e.g.
LSR n above).

B.1.2. LDP to CR Primitives

CR_RECEIVED_REQ( TLV_List, Identifier )

TLV_List

TLVs
assigned to be processed by all of them. For DS service, the CDR and the local constraint-based route
function.

Identifier

Locally significant unique identifier used CBS values
are set equal to associate the
received request either with a subsequent further request
or a response. For example, PDR and the identifier provided here
would be used in a subsequent LDP_SEND_REQ or LDP_SEND_RSP.

CR_LSP_STATUS( Status, Identifier )

Status

Status of a specific CRLSP Setup Request. A Status PBS respectively. An indication of zero
indicates success; other Status
whether the parameter values are given in section
Error Subcodes. This Status originated at the remote LSR

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CR-LDP Specification - 30 - Exp. Apr 1999

which either completed subject to negotiation is flagged.

The transport characteristics of the CRLSP setup or determined DS service requires that
CRLSP setup could not
Frequent frequency to be done.

Identifier

Locally significant unique identifier used requested to associate reflect the
received response with real-time delay
requirements of the original request. For example,
this identifier would be service.

In addition to the same as was used in transport characteristics, both the initial
LDP_SEND_REQ.

B.2. CR-LDP States

This document defines 3 states relative to any one specific CRLSP.
They are:

CR_Non_Existant - no state information exists relative network
provider and the customer need to this
CRLSP;

CR_In_Progress - LDP_SEND_REQ has been called in result agree on the actions enforced at
the edge. The specification of external input (e.g. - management);

CR_Established - a successful status has been received from
an earlier setup.

These states are defined such that no additional state those actions is required expected to support CRLSPs using LDP at intermediate LSRs than is already
required in LDP.

B.3. CR-LDP Events

This document defines 4 events impacting any one specific CRLSP.
They are:

CR_Start - be a CRLSP is required based on an external stimulus
(e.g. - management);

CR_Req_Received - further CRLSP setup processing part
of the service level agreement (SLA) negotiation and is required
based on CR_RECEIVED_REQ (i.e. - from an upstream LSR's CRLSP
Label Request);

CR_Setup_Complete - CRLSP setup has been successfully completed
based on CR_LSP_STATUS (with success status);

CR_LSP_Failure - Either a CRLSP could not included
in the signaling protocol. For DS service, the edge action is to drop
packets that exceed the PDR and the PBS specifications.

The signaling message will be sent in the direction of the ER path
and the LSP is established as
requested, or a setup CRLSP has dropped; based on CR_LSP_STATUS
(with error status).

B.4. CR-LDP Transitions

State transitions are defined as follows: following the normal LDP procedures. Each

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State Event Action New State
==================== ================= ====== ===============
CR_Non_Existant CR_Start 1 CR_In_Progress
CR_Non_Existant CR_Req_Rec 2 CR_Non_Existant
CR_In_Progress CR_Setup_Complete CR_Established
CR_In_Progress CR_LSP_Failure 3 CR_Non_Existant
CR_Established CR_LSP_Failure 3 CR_Non_Existant

Actions:

1) Establish CRLSP state, create CR-TLV information,
LDP_SEND_REQ.
2) Process CR-TLV (as described in "Processing of
the Constraint-Based Route TLV" section)

LSR applies its admission control rules. If sufficient resources are
not available and the parameter values are subject to negotiation,
then the LSR could negotiate down either
LDP_SEND_REQ the PDR, the PBS, or LDP_SEND_RSP.
3) Remove state information relative both.
The new parameters values are echoed back in the Label Mapping
Message. LSRs might need to re-adjust their resource reservations
based on the new traffic parameter values.

B.3. Establishing CR-LSP Supporting Delay Insensitive Applications

In this CRLSP (may notify
management, other external source initially requiring
setup). example we assume that a throughput sensitive (TS) service is
requested. For resource allocation the purposes of this transition table, illegal transitions
(not included user assigns values for PDR,
PBS, CDR, and CBS. The negotiation flag is set if the traffic
parameters are subject to negotiation.

Since the service is delay insensitive by definition, the Unspecified
frequency is signaled to indicate that the service frequency is not
an issue.

Similar to the previous example, the edge actions are not subject for
signaling and are specified in the table) service level agreement between
the user and the network provider.

For TS service, the edge rules might include marking to indicate high
discard precedence values for all packets that exceed CDR and the
CBS. The edge rules will also include dropping of packets that are ignored.

Jamoussi, et. al. January 26, 1999 [Page 31] do
not conform to either PDR and PBS.

Each LSR of the LSP is expected to run its admission control rules
and negotiate traffic parameters down if sufficient resources do not
exist. The new parameters values are echoed back in the Label Mapping
Message. LSRs might need to re-adjust their resources based on the
new traffic parameter values.

----