draft-ietf-teas-p2mp-loose-path-reopt-06.txt   draft-ietf-teas-p2mp-loose-path-reopt-07.txt 
TEAS Working Group T. Saad, Ed. TEAS Working Group T. Saad, Ed.
Internet-Draft R. Gandhi, Ed. Internet-Draft R. Gandhi, Ed.
Intended status: Standards Track Z. Ali Intended status: Standards Track Z. Ali
Expires: March 8, 2017 Cisco Systems, Inc. Expires: April 27, 2017 Cisco Systems, Inc.
R. Venator R. Venator
Defense Information Systems Agency Defense Information Systems Agency
Y. Kamite Y. Kamite
NTT Communications Corporation NTT Communications Corporation
September 4, 2016 October 24, 2016
RSVP Extensions For Re-optimization of Loosely Routed RSVP Extensions For Re-optimization of Loosely Routed
Point-to-Multipoint Traffic Engineering Label Switched Paths (LSPs) Point-to-Multipoint Traffic Engineering Label Switched Paths (LSPs)
draft-ietf-teas-p2mp-loose-path-reopt-06 draft-ietf-teas-p2mp-loose-path-reopt-07
Abstract Abstract
Re-optimization of a Point-to-Multipoint (P2MP) Traffic Engineered Re-optimization of a Point-to-Multipoint (P2MP) Traffic Engineered
(TE) Label Switched Path (LSP) may be triggered based on the need to (TE) Label Switched Path (LSP) may be triggered based on the need to
re-optimize an individual source-to-leaf (S2L) sub-LSP or a set of re-optimize an individual source-to-leaf (S2L) sub-LSP or a set of
S2L sub-LSPs, both using Sub-Group-Based Re-optimization method, or S2L sub-LSPs, both using Sub-Group-Based Re-optimization method, or
the entire P2MP-TE LSP tree using the Make-Before-Break (MBB) method. the entire P2MP-TE LSP tree using the Make-Before-Break (MBB) method.
Mechanisms that facilitate path re-optimization of loosely routed Mechanisms that facilitate path re-optimization of loosely routed
Point-to-Point (P2P) TE LSPs include a method for the ingress node to Point-to-Point (P2P) TE LSPs include a method for the ingress node to
trigger a new path re-evaluation request and a method for the mid- trigger a new path re-evaluation request and a method for the mid-
point node to notify availability of a preferred path. This document point node to notify availability of a preferred path. This document
discusses the application of these mechanisms to the re-optimization discusses the application of these mechanisms to the re-optimization
of loosely routed P2MP-TE LSPs, identifies issues in doing so and of loosely routed P2MP-TE LSPs, identifies issues in doing so and
proposes procedures to address them. proposes procedures to address them.
This document defines Resource Reservation Protocol (RSVP) signaling This document defines Resource Reservation Protocol (RSVP) signaling
extensions to allow the ingress node of a loosely routed P2MP-TE LSP extensions to allow the ingress node of a loosely routed P2MP-TE LSP
to request the re-evaluation of the entire LSP tree, and a mid-point to request the re-evaluation of the LSP tree downstream of the node,
node to notify to the ingress node that a preferable tree exists for and a mid-point node to notify to the ingress node that a preferable
the entire P2MP-TE LSP. For re-optimizing a group of S2L sub-LSPs in tree for the P2MP-TE LSP exists. For re-optimizing a group of S2L
a tree using the Sub-Group-Based Re-optimization method, an S2L sub- sub-LSPs in a tree using the Sub-Group-Based Re-optimization method,
LSP descriptor list can be used to signal one or more S2L sub-LSPs in an S2L sub-LSP descriptor list can be used to signal one or more S2L
an RSVP message. This RSVP message may need to be fragmented when sub-LSPs in an RSVP message. This RSVP message may need to be
large number of S2L sub-LSPs are added to the descriptor list. This semantically fragmented when large number of S2L sub-LSPs are added
document introduces the notion of a fragment identifier to help to the descriptor list. This document introduces the notion of a
recipient nodes unambiguously reconstruct the fragmented S2L sub-LSP fragment identifier to help recipient nodes unambiguously reconstruct
descriptor list. the fragmented S2L sub-LSP descriptor list.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
skipping to change at page 3, line 8 skipping to change at page 3, line 8
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Loosely Routed Inter-domain P2MP-TE LSP Tree . . . . . . . 5 2. Conventions Used in This Document . . . . . . . . . . . . . . 4
1.2. Existing Mechanism For Tree-Based P2MP-TE LSP 2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . . 4
Re-optimization . . . . . . . . . . . . . . . . . . . . . 5 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Existing Mechanism For Sub-Group-Based P2MP-TE LSP 2.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Loosely Routed Inter-domain P2MP-TE LSP Tree . . . . . . . 6
3.2. Existing Mechanism For Tree-Based P2MP-TE LSP
Re-optimization . . . . . . . . . . . . . . . . . . . . . 6 Re-optimization . . . . . . . . . . . . . . . . . . . . . 6
2. Conventions Used in This Document . . . . . . . . . . . . . . 7 3.3. Existing Mechanism For Sub-Group-Based P2MP-TE LSP
2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . . 7 Re-optimization . . . . . . . . . . . . . . . . . . . . . 7
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 7 4. Signaling Procedure For Loosely Routed P2MP-TE LSP
2.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 8
3. Signaling Procedure For Loosely Routed P2MP-TE LSP
Re-optimization . . . . . . . . . . . . . . . . . . . . . . . 8 Re-optimization . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Tree-Based Re-optimization . . . . . . . . . . . . . . . . 8 4.1. Tree-Based Re-optimization . . . . . . . . . . . . . . . . 8
3.2. Sub-Group-Based Re-optimization Using Fragment 4.2. Sub-Group-Based Re-optimization Using Fragment
Identifier . . . . . . . . . . . . . . . . . . . . . . . . 9 Identifier . . . . . . . . . . . . . . . . . . . . . . . . 9
4. Message and Object Definitions . . . . . . . . . . . . . . . . 10 5. Message and Object Definitions . . . . . . . . . . . . . . . . 11
4.1. P2MP-TE Tree Re-evaluation Request Flag . . . . . . . . . 10 5.1. P2MP-TE Tree Re-evaluation Request Flag . . . . . . . . . 11
4.2. Preferable P2MP-TE Tree Exists Path Error Sub-code . . . . 10 5.2. Preferable P2MP-TE Tree Exists Path Error Sub-code . . . . 11
4.3. Fragment Identifier For S2L sub-LSP Descriptor . . . . . . 11 5.3. Fragment Identifier For S2L sub-LSP Descriptor . . . . . . 11
5. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 12 6. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
6.1. P2MP-TE Tree Re-evaluation Request Flag . . . . . . . . . 12 7.1. P2MP-TE Tree Re-evaluation Request Flag . . . . . . . . . 13
6.2. Preferable P2MP-TE Tree Exists Path Error Sub-code . . . . 13 7.2. Preferable P2MP-TE Tree Exists Path Error Sub-code . . . . 13
6.3. Fragment Identifier For S2L sub-LSP Descriptor . . . . . . 13 7.3. Fragment Identifier For S2L sub-LSP Descriptor . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1. Normative References . . . . . . . . . . . . . . . . . . . 15 9.1. Normative References . . . . . . . . . . . . . . . . . . . 16
8.2. Informative References . . . . . . . . . . . . . . . . . . 15 9.2. Informative References . . . . . . . . . . . . . . . . . . 16
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 16 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 17
Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
This document defines Resource Reservation Protocol - Traffic This document defines Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) [RFC2205] [RFC3209] signaling extensions for Engineering (RSVP-TE) [RFC2205] [RFC3209] signaling extensions for
re-optimizing loosely routed Point-to-Multipoint (P2MP) Traffic re-optimizing loosely routed Point-to-Multipoint (P2MP) Traffic
Engineered (TE) Label Switched Paths (LSPs) [RFC4875] in a Engineered (TE) Label Switched Paths (LSPs) [RFC4875] in a
Multi-Protocol Label Switching (MPLS) or Generalized MPLS (GMPLS) Multi-Protocol Label Switching (MPLS) or Generalized MPLS (GMPLS)
network. [RFC3473] network.
A P2MP-TE LSP is comprised of one or more source-to-leaf (S2L) A P2MP-TE LSP is comprised of one or more source-to-leaf (S2L)
sub-LSPs. A loosely routed P2MP-TE S2L sub-LSP is defined as one sub-LSPs. A loosely routed P2MP-TE S2L sub-LSP is defined as one
whose path does not contain the full explicit route identifying each whose path does not contain the full explicit route identifying each
node along the path to the egress node at the time of its signaling node along the path to the egress node at the time of its signaling
by the ingress node. Such an S2L sub-LSP is signaled with no by the ingress node. Such an S2L sub-LSP is signaled with no
Explicit Route Object (ERO) [RFC3209], or with an ERO that contains Explicit Route Object (ERO) [RFC3209], or with an ERO that contains
at least one loose hop, or with an ERO that contains an abstract node at least one loose next-hop, or with an ERO that contains an abstract
which identifies more than one node. This is often the case with node which identifies more than one node. This is often the case
inter-domain P2MP-TE LSPs where Path Computation Element (PCE) is not with inter-domain P2MP-TE LSPs where Path Computation Element (PCE)
used [RFC5440]. is not used [RFC5440].
As per [RFC4875], an ingress node may re-optimize the entire P2MP-TE As per [RFC4875], an ingress node may re-optimize the entire P2MP-TE
LSP by re-signaling all its S2L sub-LSP(s) or may re-optimize LSP tree by re-signaling all its S2L sub-LSP(s) using the
individual or group of S2L sub-LSP(s) i.e. individual or group of Make-Before-Break (MBB) method or may re-optimize individual or a set
destination(s). of S2L sub-LSP(s) i.e. individual or a set of destination(s) using
the Sub-Group-Based re-optimization method.
[RFC4736] defines RSVP signaling mechanisms for re-optimizing loosely
routed Point-to-Point (P2P) TE LSP(s). This document discusses the
application of those mechanisms to the re-optimization of loosely
routed P2MP-TE LSPs, identifies issues in doing so and proposes
procedures to address them.
2. Conventions Used in This Document
2.1. Key Word Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2.2. Abbreviations
ABR: Area Border Router.
AS: Autonomous System.
ERO: Explicit Route Object.
LSR: Label Switching Router.
TE LSP: Traffic Engineering Label Switched Path.
TE LSP ingress: Head-end/source node of the TE LSP.
TE LSP egress: Tail-end/destination node of the TE LSP.
2.3. Terminology
Domain: Routing or administrative domain such as an IGP area and an
autonomous system.
Interior Gateway Protocol Area (IGP Area): OSPF area or IS-IS level.
Inter-area TE LSP: A TE LSP whose path transits across at least two
different IGP areas.
Inter-AS MPLS TE LSP: A TE LSP whose path transits across at least
two different Autonomous Systems (ASes) or sub-ASes (BGP
confederations).
S2L sub-LSP: Source-to-leaf sub Label Switched Path.
The reader is assumed to be familiar with the terminology in
[RFC4875] and [RFC4736].
3. Overview
[RFC4736] defines RSVP signaling extensions for re-optimizing loosely [RFC4736] defines RSVP signaling extensions for re-optimizing loosely
routed Point-to-Point (P2P) TE LSP(s) as follows: routed P2P TE LSPs as follows:
o A mid-point LSR that expands loose next-hop(s) sends a solicited o A mid-point LSR that expands loose next-hop(s) sends a solicited
or unsolicited PathErr with the Notify error code (25 as defined in or unsolicited PathErr with the Notify error code 25 (as defined
[RFC3209]) with sub-code 6 to indicate "Preferable Path Exists" to in [RFC3209]) with sub-code 6 to indicate "Preferable Path Exists"
the ingress node. to the ingress node.
o An ingress node triggers a path re-evaluation request at all o An ingress node triggers a path re-evaluation request at all
mid-point LSR(s) that expands loose next-hop(s) by setting the "Path mid-point LSR(s) that expands loose next-hop(s) by setting the
Re-evaluation Request" flag (0x20) in SESSION_ATTRIBUTES Object in "Path Re-evaluation Request" flag (0x20) in SESSION_ATTRIBUTES
the Path message. Object in the Path message.
o The ingress node upon receiving this PathErr either solicited or o The ingress node upon receiving this PathErr with the Notify error
unsolicited initiates re-optimization of the LSP with a different code either solicited or unsolicited initiates re-optimization of
LSP-ID. the LSP using the MBB method with a different LSP-ID.
The following sections discuss the issues that may arise when The following sections discuss the issues that may arise when
applying the mechanisms defined in [RFC4736] for re-optimizing applying the mechanisms defined in [RFC4736] for re-optimizing
loosely routed P2MP-TE LSPs. loosely routed P2MP-TE LSPs.
1.1. Loosely Routed Inter-domain P2MP-TE LSP Tree 3.1. Loosely Routed Inter-domain P2MP-TE LSP Tree
An example of a loosely routed inter-domain P2MP-TE LSP tree is shown An example of a loosely routed inter-domain P2MP-TE LSP tree is shown
in Figure 1. In this example, the P2MP-TE LSP tree consists of 3 S2L in Figure 1. In this example, the P2MP-TE LSP tree consists of 3 S2L
sub-LSPs, to destinations (i.e. leafs) R10, R11 and R12 from the sub-LSPs, to destinations (i.e. leafs) R10, R11 and R12 from the
ingress node (i.e. source) R1. Nodes R2 and R5 are branch nodes and ingress node (i.e. source) R1. Nodes R2 and R5 are branch nodes and
nodes ABR3, ABR4, ABR7, ABR8 and ABR9 are area border routers. For nodes ABR3, ABR4, ABR7, ABR8 and ABR9 are area border routers. For
the S2L sub-LSP to destination R10, nodes ABR3, ABR7 and R10 are the S2L sub-LSP to destination R10, nodes ABR3, ABR7 and R10 are
defined as loose hops. For the S2L sub-LSP to destination R11, nodes defined as loose next-hops. For the S2L sub-LSP to destination R11,
ABR3, ABR8 and R11 are defined as loose hops. For the S2L sub-LSP to nodes ABR3, ABR8 and R11 are defined as loose next-hops. For the S2L
destination R12, nodes ABR4, ABR9 and R12 are defined as loose hops. sub-LSP to destination R12, nodes ABR4, ABR9 and R12 are defined as
loose next-hops.
<--area1--><--area0--><-area2-> <--area1--><--area0--><-area2->
ABR7---R10 ABR7---R10
/ /
/ /
ABR3---R5 ABR3---R5
/ \ / \
/ \ / \
R1---R2 ABR8---R11 R1---R2 ABR8---R11
\ \
\ \
ABR4---R6 ABR4---R6
\ \
\ \
ABR9---R12 ABR9---R12
Figure 1: An Example of Loosely Routed Inter-domain P2MP-TE LSP Tree Figure 1: An Example of Loosely Routed Inter-domain P2MP-TE LSP Tree
1.2. Existing Mechanism For Tree-Based P2MP-TE LSP Re-optimization 3.2. Existing Mechanism For Tree-Based P2MP-TE LSP Re-optimization
Mechanisms defined in [RFC4736] can be easily applied to trigger the Mechanisms defined in [RFC4736] can be easily applied to trigger the
re-optimization of individual or group of S2L sub-LSP(s). However, re-optimization of individual or group of S2L sub-LSP(s). However,
to apply these [RFC4736] mechanisms for triggering the to apply these [RFC4736] mechanisms for triggering the
re-optimization of an entire P2MP-TE LSP tree, an ingress node needs re-optimization of a P2MP-TE LSP tree, an ingress node needs to send
to send path re-evaluation requests on all (typically 100s of) S2L path re-evaluation requests on all (typically 100s of) S2L sub-LSPs
sub-LSPs and the mid-point LSR needs to send notify PathErrs for all and the mid-point LSR needs to send PathErrs with the Notify error
S2L sub-LSPs. Such mechanisms may lead to the following issues: code for all S2L sub-LSPs. Such mechanisms may lead to the following
issues:
o A mid-point LSR that expands loose next-hop(s) may have to o A mid-point LSR that expands loose next-hop(s) may have to
accumulate the received path re-evaluation request(s) for all S2L accumulate the received path re-evaluation request(s) for all S2L
sub-LSPs (e.g. by using a wait timer) and interpret them as a sub-LSPs (e.g. by using a wait timer) and interpret them as a
re-optimization request for the whole P2MP-TE LSP tree. Otherwise, a re-optimization request for the whole P2MP-TE LSP tree.
mid-point LSR may prematurely notify "Preferable Path Exists" for one Otherwise, a mid-point LSR may prematurely notify "Preferable Path
or a sub-set of S2L sub-LSPs. Exists" for one or a sub-set of S2L sub-LSPs.
o Similarly, the ingress node may have to heuristically determine o Similarly, the ingress node may have to heuristically determine
when to perform entire P2MP-TE LSP tree re-optimization and when to when to perform P2MP-TE LSP tree re-optimization and when to
perform S2L sub-LSP re-optimization. For example, an implementation perform S2L sub-LSP re-optimization. For example, an
may choose to delay re-optimization long enough to allow all implementation may choose to delay re-optimization long enough to
PathErr(s) to be received. Such timer-based procedures may produce allow all PathErr(s) to be received. Such timer-based procedures
undesired results. may produce undesired results.
o The ingress node that receives (un)solicited PathErr o The ingress node that receives (un)solicited PathErr(s) with the
notification(s) for individual S2L sub-LSP(s), may prematurely start Notify error code for individual S2L sub-LSP(s), may prematurely
re-optimizing the sub-set of S2L sub-LSPs. However, as mentioned in start re-optimizing the sub-set of S2L sub-LSPs. However, as
[RFC4875] Section 14.2, such sub-group based re-optimization mentioned in [RFC4875] Section 14.2, such sub-group based re-
procedure may result in data duplication that can be avoided if the optimization procedure may result in data duplication that can be
entire P2MP-TE LSP tree is re-optimized using a different LSP-ID, avoided if the entire P2MP-TE LSP tree is re-optimized using the
especially if the ingress node eventually receives PathErr Make-Before-Break method with a different LSP-ID, especially if
notifications for all S2L sub-LSPs of the P2MP-TE LSP tree. the ingress node eventually receives PathErrs with the Notify
error code for all S2L sub-LSPs of the P2MP-TE LSP tree.
In order to address above mentioned issues and to align In order to address above mentioned issues and to align
re-optimization of P2MP-TE LSP with P2P LSP [RFC4736], there is a re-optimization of P2MP-TE LSP with P2P LSP [RFC4736], there is a
need for a mechanism to trigger re-optimization of the LSP tree by need for a mechanism to trigger re-optimization of the LSP tree by
re-signaling all S2L sub-LSPs with a different LSP-ID. To meet this re-signaling all S2L sub-LSPs with a different LSP-ID. To meet this
requirement, this document defines RSVP-TE signaling extensions for requirement, this document defines RSVP-TE signaling extensions for
the ingress node to trigger the re-evaluation of the P2MP LSP tree on the ingress node to trigger the re-evaluation of the P2MP LSP tree on
every hop that has a next-hop defined as a loose or abstract hop for every hop that has a next-hop defined as a loose or abstract hop for
one or more S2L sub-LSP path, and a mid-point LSR to signal to the one or more S2L sub-LSP path, and a mid-point LSR to signal to the
ingress node that a preferable LSP tree exists (compared to the ingress node that a preferable LSP tree exists (compared to the
current path) or that the whole P2MP-TE LSP must be re-optimized current path) or that the whole P2MP-TE LSP must be re-optimized
(because of maintenance required on the TE LSP path). (because of maintenance required on the TE LSP path).
1.3. Existing Mechanism For Sub-Group-Based P2MP-TE LSP Re-optimization 3.3. Existing Mechanism For Sub-Group-Based P2MP-TE LSP Re-optimization
Applying the procedures discussed in RFC4736 in conjunction with the Applying the procedures discussed in RFC4736 in conjunction with the
Sub-Group-Based Re-Optimization procedures ([RFC4875], Section 14.2), Sub-Group-Based Re-Optimization procedures ([RFC4875], Section 14.2),
an ingress node MAY trigger path re-evaluation requests for a set of an ingress node MAY trigger path re-evaluation requests for a set of
S2L sub-LSPs in a single Path message using S2L sub-LSP descriptor S2L sub-LSPs in a single Path message using S2L sub-LSP descriptor
list. Similarly, a mid-point LSR may send a PathErr message (with list. Similarly, a mid-point LSR may send a PathErr with the Notify
Error code 25, sub-code 6) containing a list of S2L sub-LSPs error code 25 and sub-code 6 containing a list of S2L sub-LSPs
transiting through the LSR using an S2L sub-LSP descriptor list to transiting through the LSR using an S2L sub-LSP descriptor list to
notify the ingress node. This method can be used for re-optimizing a notify the ingress node. This method can be used for re-optimizing a
sub-group of S2L sub-LSPs within an LSP tree using the same LSP-ID. sub-group of S2L sub-LSPs within an LSP tree using the same LSP-ID.
This method can alleviate the scale issue associated with sending This method can alleviate the scale issue associated with sending
RSVP messages for individual S2L sub-LSPs. However, this procedure RSVP messages for individual S2L sub-LSPs. However, this procedure
can lead to the following issues when used to re-optimize the LSP can lead to the following issues when used to re-optimize the LSP
tree: tree:
o Path message that is intended to carry the path re-evaluation o Path message that is intended to carry the path re-evaluation
request as defined in [RFC4736] with a full list of S2L sub-LSPs in request as defined in [RFC4736] with a full list of S2L sub-LSPs
S2L sub-LSPs descriptor list will be decomposed at branching LSRs, in S2L sub-LSPs descriptor list will be decomposed at branching
and only a subset of the S2L sub-LSPs that are routed over the same LSRs, and only a subset of the S2L sub-LSPs that are routed over
next-hop will be added in the descriptor list of the Path message the same next-hop will be added in the descriptor list of the Path
propagated to downstream mid-point LSRs. Consequently, when a message propagated to downstream mid-point LSRs. Consequently,
preferable path exists at such mid-point LSRs, the PathErr can only when a preferable path exists at such mid-point LSRs, the PathErr
include the sub-set of S2L sub-LSPs traversing the LSR. In this with the Notify error code can only include the sub-set of S2L
case, at the ingress node there is no way to distinguish which mode sub-LSPs traversing the LSR. In this case, at the ingress node
of re-optimization to invoke, i.e. sub-group based re-optimization there is no way to distinguish which mode of re-optimization to
using the same LSP-ID or tree based re-optimization using a different invoke, i.e. sub-group based re-optimization using the same LSP-ID
LSP-ID. or tree based re-optimization using a different LSP-ID.
o An LSR may fragment a large RSVP message (when a combined message o An LSR may semantically fragment a large RSVP message (when a
may not be large enough to fit all S2L sub-LSPs). In this case, the combined message may not be large enough to fit all S2L sub-LSPs).
ingress node may receive multiple PathErrs with sub-sets of S2L sub- In this case, the ingress node may receive multiple PathErrs with
LSPs in each (due to either the combined Path message getting sub-sets of S2L sub-LSPs in each (due to either the combined Path
fragmented or the combined PathErr message getting fragmented) and message getting fragmented or the combined PathErr message getting
would require additional logic to determine how to re-optimize the fragmented) and would require additional logic to determine how to
LSP tree (for example, waiting for some time to aggregate all re-optimize the LSP tree (for example, waiting for some time to
possible PathErr messages before taking an action). When fragmented, aggregate all possible PathErr messages before taking an action).
RSVP messages may arrive out of order, and the receiver has no way of When fragmented, RSVP messages may arrive out of order, and the
knowing the beginning and end of the S2L sub-LSP list. receiver has no way of knowing the beginning and end of the S2L
sub-LSP list.
In order to address the above mentioned issues caused by RSVP message In order to address the above mentioned issues caused by RSVP message
fragmentation, this document proposes the use of fragment identifier semantic fragmentation, this document proposes the use of fragment
for the S2L sub-LSP descriptor list when combining large number of identifier for the S2L sub-LSP descriptor list when combining large
S2L sub-LSPs in an RSVP message. number of S2L sub-LSPs in an RSVP message.
2. Conventions Used in This Document
2.1. Key Word Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2.2. Abbreviations
ABR: Area Border Router.
AS: Autonomous System.
ERO: Explicit Route Object.
LSR: Label Switching Router.
TE LSP: Traffic Engineering Label Switched Path.
TE LSP ingress: Head-end/source of the TE LSP.
TE LSP egress: Tail-end/destination of the TE LSP.
2.3. Terminology
Domain: Routing or administrative domain such as an IGP area and an
autonomous system.
Interior Gateway Protocol Area (IGP Area): OSPF area or IS-IS level.
Inter-area TE LSP: A TE LSP whose path transits across at least two
different IGP areas.
Inter-AS MPLS TE LSP: A TE LSP whose path transits across at least
two different Autonomous Systems (ASes) or sub-ASes (BGP
confederations).
S2L sub-LSP: Source-to-leaf sub Label Switched Path.
The reader is assumed to be familiar with the terminology in
[RFC4875] and [RFC4736].
3. Signaling Procedure For Loosely Routed P2MP-TE LSP Re-optimization 4. Signaling Procedure For Loosely Routed P2MP-TE LSP Re-optimization
3.1. Tree-Based Re-optimization 4.1. Tree-Based Re-optimization
To evaluate an entire P2MP-TE LSP tree on mid-point LSRs that expand To evaluate a P2MP-TE LSP tree on mid-point LSRs that expand loose
loose next-hop(s), an ingress node MAY send a Path message with next-hop(s), an ingress node MAY send a Path message with "P2MP-TE
"P2MP-TE Tree Re-evaluation Request" defined in this document. The Tree Re-evaluation Request (value TBA1)" defined in this document.
ingress node SHOULD select one of the S2L sub-LSPs of the P2MP-TE LSP The ingress node selects one of the S2L sub-LSPs of the P2MP-TE LSP
tree transiting a mid-point LSR to trigger the re-evaluation request. tree transiting a mid-point LSR to trigger the re-evaluation request.
The ingress node MAY send a re-evaluation request to each border LSR The ingress node MAY send a re-evaluation request to each border LSR
on the path of the LSP tree. on the path of the LSP tree.
A mid-point LSR that expands loose next-hop(s) for one or more S2L A mid-point LSR that expands loose next-hop(s) for one or more S2L
sub-LSP path(s) SHOULD do the following upon receiving a Path message sub-LSP path(s) SHOULD do the following upon receiving a Path message
with the "P2MP-TE Tree Re-evaluation Request" bit set: with the "P2MP-TE Tree Re-evaluation Request" flag set:
o The mid-point LSR SHOULD check for a preferable P2MP-TE LSP tree o The mid-point LSR SHOULD check for a preferable P2MP-TE LSP tree
by re-evaluating all S2L sub-LSP(s) that are expanded paths of the by re-evaluating all S2L sub-LSP(s) that are expanded paths of the
loose next-hops of the P2MP-TE LSP. loose next-hops of the P2MP-TE LSP.
o If a preferable P2MP-TE LSP tree is found, the mid-point LSR MAY o If a preferable P2MP-TE LSP tree is found, the mid-point LSR MAY
send an RSVP PathErr to the ingress node with Error code 25 (Notify send an RSVP PathErr with the Notify error code 25 defined in
Error) defined in [RFC3209] and sub-code "Preferable P2MP-TE Tree [RFC3209] and sub-code "Preferable P2MP-TE Tree Exists (value
Exists" defined in this document. The mid-point LSR, in turn, SHOULD TBA2)" defined in this document to the ingress node. The mid-
NOT propagate the "P2MP-TE Tree Re-evaluation Request" bit in point LSR, in turn, SHOULD NOT propagate the "P2MP-TE Tree Re-
subsequent RSVP Path messages sent downstream for the re-evaluated evaluation Request" flag in the subsequent RSVP Path messages sent
P2MP-TE LSP. downstream for the re-evaluated P2MP-TE LSP.
o If no preferable tree for P2MP-TE LSP can be found, the o If no preferable tree for P2MP-TE LSP can be found, the
recommended mode is that the mid-point LSR that expands loose next- recommended mode is that the mid-point LSR that expands loose
hop(s) for one or more S2L sub-LSP path(s) SHOULD propagate the next-hop(s) for one or more S2L sub-LSP path(s) SHOULD propagate
request downstream by setting the "P2MP-TE Tree Re-evaluation the request downstream by setting the "P2MP-TE Tree Re-evaluation
Request" bit in the LSP_ATTRIBUTES Object of RSVP Path message. Request" flag in the LSP_ATTRIBUTES Object of the RSVP Path
message.
A mid-point LSR MAY send an unsolicited PathErr message with A mid-point LSR MAY send an unsolicited PathErr with the Notify error
"Preferable P2MP-TE Tree Exists" PathErr to the ingress node to code and sub-code "Preferable P2MP-TE Tree Exists" to the ingress
notify of a preferred P2MP-TE LSP tree when it determines it exists. node to notify of a preferred P2MP-TE LSP tree when it determines it
In this case, the mid-point LSR that expands loose next-hop(s) for exists. In this case, the mid-point LSR that expands loose next-
one or more S2L sub-LSP path(s) SHOULD select one of the S2L sub- hop(s) for one or more S2L sub-LSP path(s) selects one of the S2L
LSP(s) of the P2MP-TE LSP tree to send this PathErr message to the sub-LSP(s) of the P2MP-TE LSP tree to send this PathErr message to
ingress node. the ingress node.
The sending of an RSVP PathErr Notify message "Preferable P2MP-TE The sending of an RSVP PathErr with the Notify error code and
Tree Exists" to the ingress node SHALL notify the ingress node of the "Preferable P2MP-TE Tree Exists" sub-code to the ingress node
existence of a preferable P2MP-TE LSP tree and upon receiving this notifies the ingress node of the existence of a preferable P2MP-TE
PathErr, the ingress node MAY trigger re-optimization of the LSP LSP tree and upon receiving this PathErr, the ingress node MAY
using a different LSP-ID. trigger re-optimization of the LSP using the MBB method with a
different LSP-ID.
3.2. Sub-Group-Based Re-optimization Using Fragment Identifier 4.2. Sub-Group-Based Re-optimization Using Fragment Identifier
It might be preferable, as per [RFC4875], to re-optimize the entire It might be preferable, as per [RFC4875], to re-optimize the entire
P2MP-TE LSP by re-signaling all of its S2L sub-LSP(s) (Section 14.1, P2MP-TE LSP by re-signaling all of its S2L sub-LSP(s) (Section 14.1,
"Make-before-Break") or to re-optimize individual or group of S2L "Make-before-Break") or to re-optimize individual or group of S2L
sub-LSP(s) i.e. individual or group of destination(s) (Section 14.2 sub-LSP(s) i.e. individual or group of destination(s) (Section 14.2
"Sub-Group-Based Re-Optimization" in [RFC4875]), both using the same "Sub-Group-Based Re-Optimization" in [RFC4875]), both using the same
LSP-ID. For loosely routed S2L sub-LSPs, this can be achieved by LSP-ID. For loosely routed S2L sub-LSPs, this can be achieved by
using the procedures defined in [RFC4736] to re-optimize one or more using the procedures defined in [RFC4736] to re-optimize one or more
S2L sub-LSP(s) of the P2MP-TE LSP. S2L sub-LSP(s) of the P2MP-TE LSP.
An ingress node may trigger path re-evaluation requests using the An ingress node may trigger path re-evaluation requests using the
procedures defined in [RFC4736] for a set of S2L sub-LSPs by procedures defined in [RFC4736] for a set of S2L sub-LSPs by
combining multiple Path messages using an S2L sub-LSP descriptor list combining multiple Path messages using an S2L sub-LSP descriptor list
[RFC4875]. An S2L sub-LSP descriptor list is created using a series [RFC4875]. An S2L sub-LSP descriptor list is created using a series
of S2L_SUB_LSP Objects as defined in [RFC4875]. Similarly, a mid- of S2L_SUB_LSP Objects as defined in [RFC4875]. Similarly, a mid-
point LSR may send a PathErr message (with Error code 25, sub-code 6, point LSR may send a PathErr with the Notify error code (value 25)
Preferable Path Exists) containing a list of S2L sub-LSPs transiting and "Preferable Path Exists" (sub-code 6) containing a list of S2L
through the LSR using an S2L sub-LSP descriptor list to notify the sub-LSPs transiting through the LSR using an S2L sub-LSP descriptor
ingress node of preferable paths available. list to notify the ingress node of preferable paths available.
As per [RFC4875] (Section 5.2.3, "Transit Fragmentation of Path State As per [RFC4875] (Section 5.2.3, "Transit Fragmentation of Path State
Information"), when a Path message is not large enough to fit all S2L Information"), when a Path message is not large enough to fit all S2L
sub-LSPs in the descriptor list, an LSR may fragment the message. In sub-LSPs in the descriptor list, an LSR may semantically fragment the
this case, the LSR MAY add S2L_SUB_LSP_FRAG Object defined in this message. In this case, the LSR MUST add the S2L_SUB_LSP_FRAG Object
document in the S2L sub-LSP descriptor list to be able to rebuild the defined in this document in the S2L sub-LSP descriptor to be able to
list from the received fragments that may arrive out of order. rebuild the list from the received fragments that may arrive out of
order.
The S2L_SUB_LSP_FRAG Object defined in this document is optional. The S2L_SUB_LSP_FRAG Object defined in this document is optional.
However, a node MUST add the S2L_SUB_LSP_FRAG Object for each However, a node MUST add the S2L_SUB_LSP_FRAG Object for each
fragment in S2L sub-LSP descriptor list when the RSVP message needs fragment in S2L sub-LSP descriptor when the RSVP message needs to be
to be fragmented. fragmented.
A mid-point LSR SHOULD wait to accumulate all S2L sub-LSPs before A mid-point LSR SHOULD wait to accumulate all S2L sub-LSPs before
attempting to re-evaluate preferable path when a Path message for attempting to re-evaluate preferable path when a Path message for
"Path Re-evaluation Request" is received with S2L_SUB_LSP_FRAG "Path Re-evaluation Request" is received with S2L_SUB_LSP_FRAG
Object. If a mid-point LSR does not receive all fragments of the Object. If a mid-point LSR does not receive all fragments of the
Path message (for example, when fragments are lost), it SHOULD Path message (for example, when fragments are lost) within a
trigger re-evaluation of all S2L sub-LSPs of the P2MP-TE LSP configurable time interval, it SHOULD trigger re-evaluation of all
transiting on the node. An ingress node SHOULD wait to accumulate S2L sub-LSPs of the P2MP-TE LSP transiting on the node. A mid-point
all S2L sub-LSPs before attempting to trigger re-optimization when a LSR MUST receive at least one fragment of the Path message to trigger
PathErr message with "Preferable Path Exists" is received with a this behaviour.
An ingress node SHOULD wait to accumulate all S2L sub-LSPs before
attempting to trigger re-optimization when a PathErr with Notify
error code and "Preferable Path Exists" sub-code is received with a
S2L_SUB_LSP_FRAG Object. If an ingress node does not receive all S2L_SUB_LSP_FRAG Object. If an ingress node does not receive all
fragments of the PathErr message (for example, when fragments are fragments of the PathErr message (for example, when fragments are
lost), it SHOULD trigger re-optimization of all S2L sub-LSPs of the lost) within a configurable time interval, it SHOULD trigger re-
P2MP-TE LSP transiting on the mid-point node that had sent the optimization of all S2L sub-LSPs of the P2MP-TE LSP transiting on the
PathErr message. mid-point node that had sent the PathErr message. An ingress node
MUST receive at least one fragment of the PathErr message to trigger
this behaviour.
The new object S2L_SUB_LSP_FRAG defined in this document has a wider The S2L_SUB_LSP_FRAG Object defined in this document has a wider
applicability other than the P2MP-TE LSP re-optimization but it is applicability in addition to the P2MP-TE LSP re-optimization. It can
outside the scope of this document. also be used (in Path and Resv messages) to setup a new P2MP-TE LSP,
send other PathErr messages as well as Path Tear and Resv Tear
messages for a set of S2L sub-LSPs. This is outside the scope of
this document.
4. Message and Object Definitions 5. Message and Object Definitions
4.1. P2MP-TE Tree Re-evaluation Request Flag 5.1. P2MP-TE Tree Re-evaluation Request Flag
In order to trigger a tree re-evaluation request, a new flag is In order to trigger a tree re-evaluation request, a new flag is
defined in Attributes Flags TLV of the LSP_ATTRIBUTES Object defined in Attributes Flags TLV of the LSP_ATTRIBUTES Object
[RFC5420] as follows: [RFC5420] as follows:
Bit Number (to be assigned by IANA): P2MP-TE Tree Re-evaluation Bit Number (TBA1, to be assigned by IANA): P2MP-TE Tree
Request flag Re-evaluation Request flag
The "P2MP-TE Tree Re-evaluation Request" flag is meaningful in a Path The "P2MP-TE Tree Re-evaluation Request" flag is meaningful in a Path
message of a P2MP-TE S2L sub-LSP and is inserted by the ingress node. message of a P2MP-TE S2L sub-LSP and is inserted by the ingress node
using the message format defined in [RFC6510].
5.2. Preferable P2MP-TE Tree Exists Path Error Sub-code
4.2. Preferable P2MP-TE Tree Exists Path Error Sub-code
In order to indicate to an ingress node that a preferable P2MP-TE LSP In order to indicate to an ingress node that a preferable P2MP-TE LSP
tree exists, the following new sub-code for PathErr code 25 (Notify tree exists, the following new sub-code for PathErr with Notify error
Error) [RFC3209] is defined: code 25 [RFC3209] is defined:
Sub-code (to be assigned by IANA): Preferable P2MP-TE Tree Exists Sub-code (TBA2, to be assigned by IANA): Preferable P2MP-TE Tree
sub-code Exists sub-code
When a preferable path for P2MP-TE LSP tree exists, the mid-point LSR When a preferable path for P2MP-TE LSP tree exists, the mid-point LSR
sends a solicited or unsolicited "Preferable P2MP-TE Tree Exists" sends a solicited or unsolicited "Preferable P2MP-TE Tree Exists"
PathErr notification to the ingress node of the P2MP-TE LSP. sub-code with PathErr with Notify error code 25 to the ingress node
of the P2MP-TE LSP.
4.3. Fragment Identifier For S2L sub-LSP Descriptor 5.3. Fragment Identifier For S2L sub-LSP Descriptor
An S2L_SUB_LSP Object [RFC4875] identifies a particular S2L sub-LSP The S2L_SUB_LSP Object [RFC4875] identifies a particular S2L sub-LSP
belonging to the P2MP-TE LSP. An S2L sub-LSP descriptor list is belonging to the P2MP-TE LSP. An S2L sub-LSP descriptor list is
created using a series of S2L_SUB_LSP Objects as defined in created using a series of S2L_SUB_LSP Objects as defined in
[RFC4875]. The RSVP message may need to be fragmented due to large [RFC4875]. The RSVP message may need to be semantically fragmented
number of S2L sub-LSPs added in the descriptor list, and such [RFC4875] due to large number of S2L sub-LSPs added in the descriptor
fragments may be received our of order. To be able to rebuild the list, and such fragments may be received our of order. To be able to
fragmented S2L sub-LSP descriptor list correctly, the following new rebuild the fragmented S2L sub-LSP descriptor list correctly, the
type is defined for the S2L_SUB_LSP Object [RFC4875] to identify the following Object is defined to identify the fragments.
fragments.
S2L_SUB_LSP_FRAG: Class-Num 50, C-Type TBA3 by IANA S2L_SUB_LSP_FRAG: Class-Num TBA3 by IANA
+---------------+---------------+---------------+---------------+ +---------------+---------------+---------------+---------------+
| Length (12 bytes) | Class-Num 50 | C-Type TBA3 | | Length (8 bytes) | Class-Num TBA3| C-Type 1 |
+---------------+---------------+---------------+---------------+
| Reserved | Fragment ID |
+---------------+---------------+---------------+---------------+ +---------------+---------------+---------------+---------------+
| Fragments Total | Fragment Number | | Fragment ID | Fragments Tot | Fragment Num |
+---------------+---------------+---------------+---------------+ +---------------+---------------+---------------+---------------+
Fragment ID: 16-bit integer in the range of 1 to 65535. This value Fragment ID: 16-bit integer in the range of 1 to 65535.
is incremented for each new RSVP message that needs to be
fragmented. The scope of the fragment ID is limited to the RSVP
message type (e.g. Path) carrying the fragment. In other words,
fragment IDs do not have any correlation between different RSVP
message types (e.g. Path and PathErr).
Fragments Total: 16-bit integer in the range of 1 to 65535. This This value is incremented for each new RSVP message that needs to
value indicates the number of fragments sent for the given RSVP be semantically fragmented. The fragment ID is reset to 1 when it
message. reaches the maximum value of 65535. The scope of the fragment ID
is limited to the RSVP message type (e.g. Path) carrying the
fragment. In other words, fragment IDs do not have any
correlation between different RSVP message types (e.g. Path and
PathErr). The receiver does not check to ensure if the
consecutive new RSVP messages (e.g. Path messages) are received
with fragment IDs incremented by 1.
Fragment Number: 16-bit integer in the range of 1 to 65535. This Fragments Total: 8-bit integer in the range of 1 to 255.
value indicates the position of this fragment in the given RSVP
message.
The S2L_SUB_LSP_FRAG Object is added before adding the This value indicates the number of fragments sent for the given
S2L_SUB_LSP_IPv4 or S2L_SUB_LSP_IPv6 Object in the fragmented RSVP RSVP message. This value MUST be the same in all fragmented RSVP
message. messages with a common Fragment ID.
5. Compatibility Fragment Number: 8-bit integer in the range of 1 to 255.
The LSP_ATTRIBUTES Object has been defined in [RFC5420] with class This value indicates the position of this fragment in the given
numbers in the form 11bbbbbb, which ensures compatibility with RSVP message.
non-supporting nodes. Per [RFC2205], nodes not supporting this
extension will ignore the new flag defined in this document but The format of an S2L sub-LSP descriptor message is as follows:
forward it without modification.
<S2L sub-LSP descriptor> ::=
[ <S2L_SUB_LSP_FRAG> ]
<S2L_SUB_LSP>
[ <P2MP SECONDARY_EXPLICIT_ROUTE> ]
The S2L_SUB_LSP_FRAG Object is added before adding the S2L_SUB_LSP
Object in the semantically fragmented RSVP message.
6. Compatibility
The LSP_ATTRIBUTES Object has been defined in [RFC5420] and its
message formats in [RFC6510] with class numbers in the form 11bbbbbb,
which ensures compatibility with non-supporting nodes. Per
[RFC2205], nodes not supporting this extension will ignore the new
flag defined for this Object in this document but forward it without
modification.
The S2L_SUB_LSP_FRAG Object has been defined with class numbers in The S2L_SUB_LSP_FRAG Object has been defined with class numbers in
the form 11bbbbbb, which ensures compatibility with non-supporting the form 11bbbbbb, which ensures compatibility with non-supporting
nodes. Per [RFC2205], nodes not supporting new S2L_SUB_LSP_FRAG nodes. Per [RFC2205], nodes not supporting this Object will ignore
Object will ignore them but forward it without modification. the Object but forward it without modification.
6. IANA Considerations 7. IANA Considerations
IANA is requested to administer assignment of new values for IANA is requested to administer assignment of new values for
namespace defined in this document and summarized in this section. namespace defined in this document and summarized in this section.
6.1. P2MP-TE Tree Re-evaluation Request Flag 7.1. P2MP-TE Tree Re-evaluation Request Flag
IANA maintains a name space for RSVP-TE TE parameters "Resource IANA maintains a name space for RSVP-TE TE parameters "Resource
Reservation Protocol-Traffic Engineering (RSVP-TE) Parameters" (see Reservation Protocol-Traffic Engineering (RSVP-TE) Parameters" (see
http://www.iana.org/assignments/rsvp-te-parameters). From the http://www.iana.org/assignments/rsvp-te-parameters). From the
registries in this name space "Attribute Flags", allocation of new registries in this name space "Attribute Flags", allocation of new
flag is requested (Section 4.1). flag is requested (Section 5.1).
The following new flag is defined for the Attributes Flags TLV in the The following new flag is defined for the Attributes Flags TLV in the
LSP_ATTRIBUTES Object [RFC5420]. The numeric value is to be assigned LSP_ATTRIBUTES Object [RFC5420]. The numeric value is to be assigned
by IANA. by IANA.
o P2MP-TE Tree Re-evaluation Request Flag: o P2MP-TE Tree Re-evaluation Request Flag:
+--------+---------------+---------+---------+---------+------------+ +--------+---------------+---------+---------+---------+------------+
| Bit No | Attribute | Carried | Carried | Carried | Reference | | Bit No | Attribute | Carried | Carried | Carried | Reference |
| | Flag Name | in Path | in Resv | in RRO | | | | Flag Name | in Path | in Resv | in RRO | |
+--------+---------------+---------+---------+---------+------------+ +--------+---------------+---------+---------+---------+------------+
| TBA1 by| P2MP-TE Tree | Yes | No | No | This | | TBA1 by| P2MP-TE Tree | Yes | No | No | This |
| IANA | Re-evaluation | | | | document | | IANA | Re-evaluation | | | | document |
+--------+---------------+---------+---------+---------+------------+ +--------+---------------+---------+---------+---------+------------+
6.2. Preferable P2MP-TE Tree Exists Path Error Sub-code 7.2. Preferable P2MP-TE Tree Exists Path Error Sub-code
IANA maintains a name space for RSVP protocol parameters "Resource IANA maintains a name space for RSVP protocol parameters "Resource
Reservation Protocol (RSVP) Parameters" (see Reservation Protocol (RSVP) Parameters" (see
http://www.iana.org/assignments/rsvp-parameters). From the http://www.iana.org/assignments/rsvp-parameters). From the
sub-registry "Sub-Codes - 25 Notify Error" in registry "Error Codes sub-registry "Sub-Codes - 25 Notify Error" in registry "Error Codes
and Globally-Defined Error Value Sub-Codes", allocation of a new and Globally-Defined Error Value Sub-Codes", allocation of a new
error code is requested (Section 4.2). error code is requested (Section 5.2).
As defined in [RFC3209], the Error Code 25 in the ERROR SPEC Object As defined in [RFC3209], the Error Code 25 in the ERROR SPEC Object
corresponds to a Notify Error PathErr. This document adds a new corresponds to PathErr with Notify error. This document adds a new
sub-code for this PathErr as follows: sub-code for this PathErr as follows:
o Preferable P2MP-TE Tree Exists sub-code: o Preferable P2MP-TE Tree Exists sub-code:
+----------+--------------------+---------+---------+-----------+ +----------+--------------------+---------+---------+-----------+
| Sub-code | Sub-code | PathErr | PathErr | Reference | | Sub-code | Sub-code | PathErr | PathErr | Reference |
| value | Description | Code | Name | | | value | Description | Code | Name | |
+----------+--------------------+---------+---------+-----------+ +----------+--------------------+---------+---------+-----------+
| TBA2 by | Preferable P2MP-TE | 25 | Notify | This | | TBA2 by | Preferable P2MP-TE | 25 | Notify | This |
| IANA | Tree Exists | | Error | document | | IANA | Tree Exists | | Error | document |
+----------+--------------------+---------+---------+-----------+ +----------+--------------------+---------+---------+-----------+
6.3. Fragment Identifier For S2L sub-LSP Descriptor 7.3. Fragment Identifier For S2L sub-LSP Descriptor
IANA maintains a name space for RSVP protocol parameters "Resource IANA maintains a name space for RSVP protocol parameters "Resource
Reservation Protocol (RSVP) Parameters" (see Reservation Protocol (RSVP) Parameters" (see
http://www.iana.org/assignments/rsvp-parameters). From the http://www.iana.org/assignments/rsvp-parameters). From the registry
sub-registry "Class Types or C-Types 50 S2L_SUB_LSP" in registry
"Class Names, Class Numbers, and Class Types", allocation of new "Class Names, Class Numbers, and Class Types", allocation of new
C-Types is requested (Section 4.3). Class-Num is requested (Section 5.3).
As defined in [RFC4875], S2L_SUB_LSP Object is defined with
Class-Number 50 to identify a particular S2L sub-LSP belonging to the
P2MP-TE LSP. This document adds one new object type for this object
as follows:
o S2L_SUB_LSP_FRAG Object type: o S2L_SUB_LSP_FRAG Object:
+-----------------+---------------------------+-----------------+ +-----------------+---------------------------+-----------------+
| C-Type value | Description | Reference | | Class-Num value | Description | Reference |
+-----------------+---------------------------+-----------------+ +-----------------+---------------------------+-----------------+
| TBA3 by IANA | S2L_SUB_LSP_FRAG | This document | | TBA3 by IANA | S2L_SUB_LSP_FRAG | This document |
+-----------------+---------------------------+-----------------+ +-----------------+---------------------------+-----------------+
7. Security Considerations 8. Security Considerations
This document defines RSVP-TE signaling extensions to allow an This document defines RSVP-TE signaling extensions to allow an
ingress node of a P2MP-TE LSP to request the re-evaluation of the ingress node of a P2MP-TE LSP to request the re-evaluation of the LSP
entire LSP tree, and for a mid-point LSR to notify the ingress node tree downstream of a node, and for a mid-point LSR to notify the
of the existence of a preferable tree by sending a PathErr. As per ingress node of the existence of a preferable tree by sending a
[RFC4736], in the case of a P2MP-TE LSP S2L sub-LSP spanning multiple PathErr. As per [RFC4736], in the case of a P2MP-TE LSP S2L sub-LSP
domains, it may be desirable for a mid-point LSR to modify the RSVP spanning multiple domains, it may be desirable for a mid-point LSR to
PathErr message defined in this document to preserve confidentiality modify the RSVP PathErr message defined in this document to preserve
across domains. Furthermore, an ingress node may decide to ignore confidentiality across domains. Furthermore, an ingress node may
this PathErr message coming from a mid-point LSR residing in another decide to ignore this PathErr message coming from a mid-point LSR
domain. Similarly, a mid-point LSR may decide to ignore the P2MP-TE residing in another domain. Similarly, a mid-point LSR may decide to
tree re-evaluation request originating from another ingress domain. ignore the P2MP-TE tree re-evaluation request originating from
another ingress domain.
This document also defines fragment identifier for the S2L sub-LSP This document also defines fragment identifier for the S2L sub-LSP
descriptor list when combining large number of S2L sub-LSPs in an descriptor when combining large number of S2L sub-LSPs in an RSVP
RSVP message and the message needs to be fragmented. The message and the message needs to be semantically fragmented. The
introduction of the fragment identifier, by itself, introduce no introduction of the fragment identifier, by itself, introduces no
additional information to signaling. For a general discussions on additional information to signaling. For a general discussions on
MPLS and GMPLS related security issues, see the MPLS/GMPLS security MPLS and GMPLS related security issues, see the MPLS/GMPLS security
framework [RFC5920]. framework [RFC5920].
8. References 9. References
8.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997. Functional Specification", RFC 2205, September 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
skipping to change at page 15, line 35 skipping to change at page 16, line 35
[RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa,
"Extensions to Resource Reservation Protocol Traffic "Extensions to Resource Reservation Protocol Traffic
Engineering (RSVP-TE) for Point-to-Multipoint TE Label Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007. Switched Paths (LSPs)", RFC 4875, May 2007.
[RFC5420] Farrel, A., Papadimitriou, D., Vasseur, JP., and Ayyangar, [RFC5420] Farrel, A., Papadimitriou, D., Vasseur, JP., and Ayyangar,
A., "Encoding of Attributes for MPLS LSP Establishment A., "Encoding of Attributes for MPLS LSP Establishment
Using Resource Reservation Protocol Traffic Engineering Using Resource Reservation Protocol Traffic Engineering
(RSVP-TE)", RFC 5420, February 2009. (RSVP-TE)", RFC 5420, February 2009.
8.2. Informative References 9.2. Informative References
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC5440] Vasseur, JP., Ed., and JL. Le Roux, Ed., "Path Computation [RFC5440] Vasseur, JP., Ed., and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440, Element (PCE) Communication Protocol (PCEP)", RFC 5440,
March 2009. March 2009.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010. Networks", RFC 5920, July 2010.
[RFC6510] Berger, L. and G. Swallow, "Resource Reservation Protocol
(RSVP) Message Formats for Label Switched Path (LSP)
Attributes Objects", RFC 6510, February 2012.
Acknowledgments Acknowledgments
The authors would like to thank Loa Andersson, Sriganesh Kini, Curtis The authors would like to thank Loa Andersson, Sriganesh Kini, Curtis
Villamizar, Dimitri Papadimitriou, Nobo Akiya and Vishnu Pavan Beeram Villamizar, Dimitri Papadimitriou, Nobo Akiya and Vishnu Pavan Beeram
for reviewing this document and providing many useful comments and for reviewing this document and providing many useful comments and
suggestions. The authors would also like to thank Ling Zeng with suggestions. The authors would also like to thank Ling Zeng with
Cisco Systems for implementing mechanisms defined in this document. Cisco Systems for implementing mechanisms defined in this document.
A special thanks to Adrian Farrel for his thorough review of this
document.
Author's Addresses Author's Addresses
Tarek Saad (editor) Tarek Saad (editor)
Cisco Systems Cisco Systems
EMail: tsaad@cisco.com EMail: tsaad@cisco.com
Rakesh Gandhi (editor) Rakesh Gandhi (editor)
Cisco Systems Cisco Systems
 End of changes. 83 change blocks. 
288 lines changed or deleted 334 lines changed or added

This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/