draft-ietf-teas-p2mp-loose-path-reopt-09.txt   rfc8149.txt 
TEAS Working Group T. Saad, Ed. Internet Engineering Task Force (IETF) T. Saad, Ed.
Internet-Draft R. Gandhi, Ed. Request for Comments: 8149 R. Gandhi, Ed.
Intended status: Standards Track Z. Ali Category: Standards Track Z. Ali
Expires: August 6, 2017 Cisco Systems, Inc. ISSN: 2070-1721 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
February 2, 2017 April 2017
RSVP Extensions For Re-optimization of Loosely Routed RSVP Extensions for Reoptimization 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-09
Abstract Abstract
Re-optimization of a Point-to-Multipoint (P2MP) Traffic Engineered The reoptimization of a Point-to-Multipoint (P2MP) Traffic
(TE) Label Switched Path (LSP) may be triggered based on the need to Engineering (TE) Label Switched Path (LSP) may be triggered based on
re-optimize an individual source-to-leaf (S2L) sub-LSP or a set of the need to reoptimize an individual source-to-leaf (S2L) sub-LSP or
S2L sub-LSPs, both using Sub-Group-Based Re-optimization method, or a set of S2L sub-LSPs, both using the Sub-Group-based reoptimization
the entire P2MP-TE LSP tree using the Make-Before-Break (MBB) method. method, or the entire P2MP-TE LSP tree using the Make-Before-Break
This document discusses the application of the existing mechanisms (MBB) method. This document discusses the application of the
for path re-optimization of loosely routed Point-to-Point (P2P) TE existing mechanisms for path reoptimization of loosely routed Point-
LSPs to the P2MP-TE LSPs, identifies issues in doing so and defines to-Point (P2P) TE LSPs to the P2MP-TE LSPs, identifies issues in
procedures to address them. When re-optimizing a large number of S2L doing so, and defines procedures to address them. When reoptimizing
sub-LSPs in a tree using the Sub-Group-Based Re-optimization method, a large number of S2L sub-LSPs in a tree using the Sub-Group-based
the S2L sub-LSP descriptor list may need to be semantically reoptimization method, the S2L sub-LSP descriptor list may need to be
fragmented. This document defines the notion of a fragment semantically fragmented. This document defines the notion of a
identifier to help recipient nodes unambiguously reconstruct the fragment identifier to help recipient nodes unambiguously reconstruct
fragmented S2L sub-LSP descriptor list. the fragmented S2L sub-LSP descriptor list.
Status of this Memo Status of This Memo
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provisions of BCP 78 and BCP 79.
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Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction ....................................................3
2. Conventions Used in This Document . . . . . . . . . . . . . . 4 2. Conventions Used in This Document ...............................4
2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . . 4 2.1. Key Word Definitions .......................................4
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Abbreviations ..............................................4
2.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Terminology ................................................4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Overview ........................................................5
3.1. Loosely Routed Inter-domain P2MP-TE LSP Tree . . . . . . . 6 3.1. Loosely Routed Inter-domain P2MP-TE LSP Tree ...............5
3.2. Existing Mechanism For Tree-Based P2MP-TE LSP 3.2. Existing Mechanism for Tree-Based P2MP-TE LSP
Re-optimization . . . . . . . . . . . . . . . . . . . . . 6 Reoptimization .............................................6
3.3. Existing Mechanism For Sub-Group-Based P2MP-TE LSP 3.3. Existing Mechanism for Sub-Group-Based P2MP-TE LSP
Re-optimization . . . . . . . . . . . . . . . . . . . . . 7 Reoptimization .............................................7
4. Signaling Extensions For Loosely Routed P2MP-TE LSP 4. Signaling Extensions for Loosely Routed P2MP-TE LSP
Re-optimization . . . . . . . . . . . . . . . . . . . . . . . 8 Reoptimization ..................................................8
4.1. Tree-Based Re-optimization . . . . . . . . . . . . . . . . 8 4.1. Tree-Based Reoptimization ..................................8
4.2. Sub-Group-Based Re-optimization Using Fragment 4.2. Sub-Group-Based Reoptimization Using Fragment Identifier ...9
Identifier . . . . . . . . . . . . . . . . . . . . . . . . 9 5. Message and Object Definitions .................................11
5. Message and Object Definitions . . . . . . . . . . . . . . . . 11 5.1. "P2MP-TE Tree Re-evaluation Request" Flag .................11
5.1. P2MP-TE Tree Re-evaluation Request Flag . . . . . . . . . 11 5.2. "Preferable P2MP-TE Tree Exists" Path Error Sub-code ......11
5.2. Preferable P2MP-TE Tree Exists Path Error Sub-code . . . . 11 5.3. Fragment Identifier for S2L Sub-LSP Descriptor ............11
5.3. Fragment Identifier For S2L sub-LSP Descriptor . . . . . . 11 6. Compatibility ..................................................12
6. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations ............................................13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 7.1. "P2MP-TE Tree Re-evaluation Request" Flag .................13
7.1. P2MP-TE Tree Re-evaluation Request Flag . . . . . . . . . 13 7.2. "Preferable P2MP-TE Tree Exists" Path Error Sub-code ......13
7.2. Preferable P2MP-TE Tree Exists Path Error Sub-code . . . . 13 7.3. Fragment Identifier for S2L Sub-LSP Descriptor ............14
7.3. Fragment Identifier For S2L sub-LSP Descriptor . . . . . . 14 8. Security Considerations ........................................14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14 9. References .....................................................15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 9.1. Normative References ......................................15
9.1. Normative References . . . . . . . . . . . . . . . . . . . 16 9.2. Informative References ....................................16
9.2. Informative References . . . . . . . . . . . . . . . . . . 16 Acknowledgments ...................................................16
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses ................................................17
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 reoptimizing loosely routed Point-to-Multipoint (P2MP) Traffic
Engineered (TE) Label Switched Paths (LSPs) [RFC4875] in a Engineering (TE) Label Switched Paths (LSPs) [RFC4875] in a
Multi-Protocol Label Switching (MPLS) or Generalized MPLS (GMPLS) Multiprotocol Label Switching (MPLS) or Generalized MPLS (GMPLS)
[RFC3473] 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], with an ERO that contains at
at least one loose next-hop, or with an ERO that contains an abstract least one "loose next hop", or with an ERO that contains an abstract
node which identifies more than one node. This is often the case node that identifies more than one node. This is often the case with
with inter-domain P2MP-TE LSPs where Path Computation Element (PCE) inter-domain P2MP-TE LSPs where a Path Computation Element (PCE) is
is not used [RFC5440]. not used [RFC5440].
As per [RFC4875], an ingress node may re-optimize the entire P2MP-TE As per [RFC4875], an ingress node may reoptimize the entire P2MP-TE
LSP tree by re-signaling all its S2L sub-LSP(s) using the LSP tree by re-signaling all its S2L sub-LSPs using the
Make-Before-Break (MBB) method or may re-optimize individual S2L sub- Make-Before-Break (MBB) method, or it may reoptimize an individual
LSP or a set of S2L sub-LSPs i.e. individual destination or a set of S2L sub-LSP or a set of S2L sub-LSPs, i.e., an individual destination
destinations, both using the Sub-Group-Based Re-optimization method. or a set of destinations, both using the Sub-Group-based
reoptimization method.
[RFC4736] defines RSVP signaling procedure for re-optimizing the [RFC4736] defines an RSVP signaling procedure for reoptimizing the
path(s) of loosely routed Point-to-Point (P2P) TE LSP(s). Those path(s) of loosely routed Point-to-Point (P2P) TE LSP(s). The
mechanisms include a method for the ingress node to trigger a new mechanisms listed in [RFC4736] include a method for the ingress node
path re-evaluation request and a method for the mid-point node to to trigger a new path re-evaluation request and a method for the
notify availability of a preferred path. This document discusses the midpoint node to send a notification regarding the availability of a
application of those mechanisms to the re-optimization of loosely preferred path. This document discusses the application of those
routed P2MP-TE LSPs, identifies issues in doing so and defines mechanisms to the reoptimization of loosely routed P2MP-TE LSPs,
procedures to address them. identifies issues in doing so, and defines procedures to address
them.
For re-optimizing a group of S2L sub-LSPs in a tree using the Sub- For reoptimizing a group of S2L sub-LSPs in a tree using the
Group-Based Re-optimization method, an S2L sub-LSP descriptor list Sub-Group-based reoptimization method, an S2L sub-LSP descriptor list
can be used to signal one or more S2L sub-LSPs in an RSVP message. can be used to signal one or more S2L sub-LSPs in an RSVP message.
This RSVP message may need to be semantically fragmented when large This RSVP message may need to be semantically fragmented when a large
number of S2L sub-LSPs are added to the descriptor list. This number of S2L sub-LSPs are added to the descriptor list. This
document defines the notion of a fragment identifier to help document defines the notion of a fragment identifier to help
recipient nodes unambiguously reconstruct the fragmented S2L sub-LSP recipient nodes unambiguously reconstruct the fragmented S2L sub-LSP
descriptor list. descriptor list.
2. Conventions Used in This Document 2. Conventions Used in This Document
2.1. Key Word Definitions 2.1. Key Word Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2.2. Abbreviations 2.2. Abbreviations
ABR: Area Border Router. ABR: Area Border Router.
AS: Autonomous System.
ERO: Explicit Route Object. ERO: Explicit Route Object.
LSR: Label Switching Router. LSP: Label Switched Path.
S2L sub-LSP: Source-to-leaf sub Label Switched Path. LSR: Label Switching Router.
TE LSP: Traffic Engineering Label Switched Path. RRO: Record Route Object.
TE LSP ingress: Head-end/source node of the TE LSP. S2L sub-LSP: Source-to-leaf sub-LSP.
TE LSP egress: Tail-end/destination node of the TE LSP. TE LSP: Traffic Engineering LSP.
2.3. Terminology 2.3. Terminology
The reader is assumed to be familiar with the terminology in This document defines the following terms:
[RFC4736] and [RFC4875].
o Ingress node: Head-end / source node of the TE LSP.
o Egress node: Tail-end / destination node of the TE LSP.
It is assumed that the reader is also familiar with the terminology
in [RFC4736] and [RFC4875].
3. Overview 3. Overview
[RFC4736] defines RSVP signaling extensions for re-optimizing loosely [RFC4736] defines RSVP signaling extensions for reoptimizing loosely
routed P2P TE LSPs as follows: routed P2P TE LSPs as follows:
o A mid-point LSR that expands loose next-hop(s) sends a solicited o A midpoint LSR that expands loose next hop(s) sends a solicited or
or unsolicited PathErr with the Notify error code 25 (as defined unsolicited PathErr with Notify error code 25 (as defined in
in [RFC3209]) with sub-code 6 to indicate "Preferable Path Exists" [RFC3209]), with sub-code 6 to indicate "Preferable Path Exists"
to 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 midpoint LSRs that expand loose next hop(s) by setting the "Path
"Path Re-evaluation Request" flag (0x20) in SESSION_ATTRIBUTES Re-evaluation Request" flag (0x20) in the SESSION_ATTRIBUTES
Object in the Path message. object in the Path message.
o The ingress node upon receiving this PathErr with the Notify error o The ingress node, upon receiving this PathErr with the Notify
code either solicited or unsolicited initiates re-optimization of error code (either solicited or unsolicited), initiates the
the LSP using the MBB method with a different LSP-ID. reoptimization of 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 reoptimizing loosely
loosely routed P2MP-TE LSPs. routed P2MP-TE LSPs.
3.1. 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 three
sub-LSPs, to destinations (i.e. leafs) R10, R11 and R12 from the S2L sub-LSPs, to destinations (i.e., leafs) R10, R11, and R12 from
ingress node (i.e. source) R1. Nodes R2 and R5 are branch nodes and the ingress node (i.e., source) R1. Nodes R2 and R5 are branch
nodes ABR3, ABR4, ABR7, ABR8 and ABR9 are area border routers. For nodes, and nodes ABR3, ABR4, ABR7, ABR8, and ABR9 are ABRs. For the
the S2L sub-LSP to destination R10, nodes ABR3, ABR7 and R10 are S2L sub-LSP to destination R10, nodes ABR3, ABR7, and R10 are defined
defined as loose next-hops. For the S2L sub-LSP to destination R11, as loose next hops. For the S2L sub-LSP to destination R11, nodes
nodes ABR3, ABR8 and R11 are defined as loose next-hops. For the S2L ABR3, ABR8, and R11 are defined as loose next hops. For the S2L
sub-LSP to destination R12, nodes ABR4, ABR9 and R12 are defined as sub-LSP to destination R12, nodes ABR4, ABR9, and R12 are defined as
loose next-hops. 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: Example of Loosely Routed Inter-domain P2MP-TE LSP Tree
3.2. Existing Mechanism For Tree-Based P2MP-TE LSP Re-optimization 3.2. Existing Mechanism for Tree-Based P2MP-TE LSP Reoptimization
Mechanisms defined in [RFC4736] can be easily applied to trigger the The mechanisms defined in [RFC4736] can be easily applied to trigger
re-optimization of individual or group of S2L sub-LSP(s). However, the reoptimization of an individual S2L sub-LSP or a group of S2L
to apply these [RFC4736] mechanisms for triggering the sub-LSPs. However, to apply those mechanisms for triggering the
re-optimization of a P2MP-TE LSP tree, an ingress node needs to send reoptimization of a P2MP-TE LSP tree, an ingress node needs to send
path re-evaluation requests on all (typically 100s of) S2L sub-LSPs path re-evaluation requests on all (typically hundreds) of the
and the mid-point LSR needs to send PathErrs with the Notify error S2L sub-LSPs, and the midpoint LSR needs to send PathErrs with the
code for all S2L sub-LSPs. Such mechanisms may lead to the following Notify error code for all S2L sub-LSPs. Such mechanisms may lead to
issues: the following issues:
o A mid-point LSR that expands loose next-hop(s) may have to o A midpoint 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. reoptimization request for the whole P2MP-TE LSP tree. Otherwise,
Otherwise, a mid-point LSR may prematurely notify "Preferable Path a midpoint LSR may prematurely send a "Preferable Path Exists"
Exists" for one or a sub-set of S2L sub-LSPs. notification for one S2L sub-LSP or a subset 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 P2MP-TE LSP tree re-optimization and when to when to perform P2MP-TE LSP tree reoptimization and when to
perform S2L sub-LSP re-optimization. For example, an perform S2L sub-LSP reoptimization. For example, an
implementation may choose to delay re-optimization long enough to implementation may choose to delay reoptimization long enough to
allow all PathErr(s) to be received. Such timer-based procedures allow all PathErrs to be received. Such timer-based procedures
may produce undesired results. may produce undesired results.
o The ingress node that receives (un)solicited PathErr(s) with the o The ingress node that receives (un)solicited PathErr(s) with the
Notify error code for individual S2L sub-LSP(s), may prematurely Notify error code for one or more individual S2L sub-LSPs may
start re-optimizing the sub-set of S2L sub-LSPs. However, as prematurely start reoptimizing the subset of S2L sub-LSPs.
mentioned in [RFC4875] Section 14.2, such sub-group based re- However, as mentioned in [RFC4875], Section 14.2, such a
optimization procedure may result in data duplication that can be Sub-Group-based reoptimization procedure may result in data
avoided if the entire P2MP-TE LSP tree is re-optimized using the duplication that can be avoided if the entire P2MP-TE LSP tree is
Make-Before-Break method with a different LSP-ID, especially if reoptimized using the MBB method with a different LSP-ID,
the ingress node eventually receives PathErrs with the Notify especially if the ingress node eventually receives PathErrs with
error code for all S2L sub-LSPs of the P2MP-TE LSP tree. 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 the above-mentioned issues and to align the
re-optimization of P2MP-TE LSP with P2P LSP [RFC4736], there is a reoptimization of P2MP-TE LSPs with P2P LSPs [RFC4736], a mechanism
need for a mechanism to trigger re-optimization of the LSP tree by is needed to trigger the reoptimization 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 paths, and a midpoint 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 reoptimized
(because of maintenance required on the TE LSP path) (see Section (because of maintenance required on the TE LSP path) (see
4.1). Section 4.1).
3.3. Existing Mechanism For Sub-Group-Based P2MP-TE LSP Re-optimization
Applying the procedures discussed in RFC4736 in conjunction with the 3.3. Existing Mechanism for Sub-Group-Based P2MP-TE LSP Reoptimization
Sub-Group-Based Re-Optimization procedures ([RFC4875], Section 14.2),
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
list. Similarly, a mid-point LSR may send a PathErr with the Notify
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
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.
This method can alleviate the scale issue associated with sending Applying the procedures discussed in [RFC4736] in conjunction with
RSVP messages for individual S2L sub-LSPs. However, this procedure the Sub-Group-based reoptimization procedures ([RFC4875],
can lead to the following issues when used to re-optimize the LSP Section 14.2), an ingress node MAY trigger path re-evaluation
tree: requests for a set of S2L sub-LSPs in a single Path message using an
S2L sub-LSP descriptor list. Similarly, a midpoint LSR may send a
PathErr with Notify error code 25 and sub-code 6 ("Preferable Path
Exists") containing a list of S2L sub-LSPs transiting through the LSR
using an S2L sub-LSP descriptor list to notify the ingress node.
This method can be used for reoptimizing a sub-group of S2L sub-LSPs
within an LSP tree using the same LSP-ID. This method can alleviate
the scaling issue associated with sending RSVP messages for
individual S2L sub-LSPs. However, this procedure can lead to the
following issues when used to reoptimize the LSP tree:
o Path message that is intended to carry the path re-evaluation o A Path message that is intended to carry the path re-evaluation
request as defined in [RFC4736] with a full list of S2L sub-LSPs request as defined in [RFC4736] with a full list of S2L sub-LSPs
in S2L sub-LSPs descriptor list will be decomposed at branching in an S2L sub-LSP descriptor list will be decomposed at branching
LSRs, and only a subset of the S2L sub-LSPs that are routed over LSRs, and only a subset of the S2L sub-LSPs that are routed over
the same next-hop will be added in the descriptor list of the Path the same next hop will be added in the descriptor list of the Path
message propagated to downstream mid-point LSRs. Consequently, message propagated to downstream midpoint LSRs. Consequently,
when a preferable path exists at such mid-point LSRs, the PathErr when a preferable path exists at such midpoint LSRs, the PathErr
with the Notify error code can only include the sub-set of S2L with the Notify error code can only include the subset of S2L
sub-LSPs traversing the LSR. In this case, at the ingress node sub-LSPs traversing the LSR. In this case, at the ingress node
there is no way to distinguish which mode of re-optimization to there is no way to distinguish which mode of reoptimization to
invoke, i.e. sub-group based re-optimization using the same LSP-ID invoke, i.e., Sub-Group-based reoptimization using the same LSP-ID
or tree based re-optimization using a different LSP-ID. or tree-based reoptimization using a different LSP-ID.
o An LSR may semantically fragment a large RSVP message (when a o An LSR may semantically fragment a large RSVP message (when a
combined message may not be large enough to fit all S2L sub-LSPs). combined message may not be large enough to fit all S2L sub-LSPs).
In this case, the ingress node may receive multiple PathErrs with In this case, the ingress node may receive multiple PathErrs with
sub-sets of S2L sub-LSPs in each (due to either the combined Path subsets of S2L sub-LSPs in each (due to either the combined Path
message getting fragmented or the combined PathErr message getting message getting fragmented or the combined PathErr message getting
fragmented) and would require additional logic to determine how to fragmented) and would require additional logic to determine how to
re-optimize the LSP tree (for example, waiting for some time to reoptimize the LSP tree (for example, waiting for some time to
aggregate all possible PathErr messages before taking an action). aggregate all possible PathErr messages before taking an action).
When fragmented, RSVP messages may arrive out of order, and the When fragmented, RSVP messages may arrive out of order, and the
receiver has no way of knowing the beginning and end of the S2L receiver has no way of knowing the beginning and end of the S2L
sub-LSP list. 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 semantic
semantic fragmentation, this document defines new fragment identifier fragmentation of an RSVP message, this document defines a new
object for the S2L sub-LSP descriptor list when combining large fragment identifier object for the S2L sub-LSP descriptor list when
number of S2L sub-LSPs in an RSVP message (see Section 4.2). combining a large number of S2L sub-LSPs in an RSVP message (see
Section 4.2).
4. Signaling Extensions For Loosely Routed P2MP-TE LSP Re-optimization 4. Signaling Extensions for Loosely Routed P2MP-TE LSP Reoptimization
4.1. Tree-Based Re-optimization 4.1. Tree-Based Reoptimization
To evaluate a P2MP-TE LSP tree on mid-point LSRs that expand loose To evaluate a P2MP-TE LSP tree on midpoint LSRs that expand loose
next-hop(s), an ingress node MAY send a Path message with "P2MP-TE next hop(s), an ingress node MAY send a Path message with the
Tree Re-evaluation Request (value TBA1)" defined in this document. "P2MP-TE Tree Re-evaluation Request" flag set (bit number 14 in the
The ingress node selects one of the S2L sub-LSPs of the P2MP-TE LSP Attribute Flags TLV) as defined in this document. The ingress node
tree transiting a mid-point LSR to trigger the re-evaluation request. selects one of the S2L sub-LSPs of the P2MP-TE LSP tree transiting a
The ingress node MAY send a re-evaluation request to each border LSR midpoint LSR to trigger the re-evaluation request. The ingress node
on the path of the LSP tree. MAY send a re-evaluation request to each border LSR on the path of
the LSP tree.
A mid-point LSR that expands loose next-hop(s) for one or more S2L A midpoint LSR that expands loose next hop(s) for one or more S2L
sub-LSP path(s) does the following upon receiving a Path message with sub-LSP paths does the following upon receiving a Path message with
the "P2MP-TE Tree Re-evaluation Request" flag set: the "P2MP-TE Tree Re-evaluation Request" flag set:
o The mid-point LSR MUST check for a preferable P2MP-TE LSP tree by o The midpoint LSR MUST check for a preferable P2MP-TE LSP tree by
re-evaluating all S2L sub-LSP(s) that are expanded paths of the re-evaluating all S2L sub-LSPs 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 MUST o If a preferable P2MP-TE LSP tree is found, the midpoint LSR MUST
send an RSVP PathErr with the Notify error code 25 defined in send to the ingress node an RSVP PathErr with Notify error code 25
[RFC3209] and sub-code "Preferable P2MP-TE Tree Exists (value [RFC3209] and sub-code 13 ("Preferable P2MP-TE Tree Exists)" as
TBA2)" defined in this document to the ingress node. The mid- defined in this document. The midpoint LSR, in turn, SHOULD NOT
point LSR, in turn, SHOULD NOT propagate the "P2MP-TE Tree Re- propagate the "P2MP-TE Tree Re-evaluation Request" flag in the
evaluation Request" flag in the subsequent RSVP Path messages sent subsequent RSVP Path messages sent downstream for the re-evaluated
downstream for the re-evaluated P2MP-TE LSP. P2MP-TE LSP.
o If no preferable tree for P2MP-TE LSP can be found, the mid-point o If no preferable tree for P2MP-TE LSPs can be found, the midpoint
LSR that expands loose next-hop(s) for one or more S2L sub-LSP LSR that expands loose next hop(s) for one or more S2L sub-LSP
path(s) MUST propagate the request downstream by setting the paths MUST propagate the request downstream by setting the
"P2MP-TE Tree Re-evaluation Request" flag in the LSP_ATTRIBUTES "P2MP-TE Tree Re-evaluation Request" flag in the LSP_ATTRIBUTES
Object of the RSVP Path message. object of the RSVP Path message.
A mid-point LSR MAY send an unsolicited PathErr with the Notify error A midpoint LSR MAY send an unsolicited PathErr with the Notify error
code and sub-code "Preferable P2MP-TE Tree Exists" to the ingress code and the "Preferable P2MP-TE Tree Exists" sub-code to the ingress
node to notify of a preferred P2MP-TE LSP tree when it determines it node to notify the ingress node of a preferred P2MP-TE LSP tree when
exists. In this case, the mid-point LSR that expands loose next- it determines that it exists. In this case, the midpoint LSR that
hop(s) for one or more S2L sub-LSP path(s) selects one of the S2L expands loose next hop(s) for one or more S2L sub-LSP paths selects
sub-LSP(s) of the P2MP-TE LSP tree to send this PathErr message to one of the S2L sub-LSPs of the P2MP-TE LSP tree to send this PathErr
the ingress node. The mid-point LSR SHOULD consider how frequently message to the ingress node. The midpoint LSR SHOULD consider how
it chooses to send such a PathErr - considering both that a PathErr frequently it chooses to send such a PathErr, considering that both
may be lost on its transit to the ingress node and that the ingress (1) a PathErr may be lost during its transit to the ingress node and
node may choose not to re-optimize the LSP when such a PathErr is (2) the ingress node may choose not to reoptimize the LSP when such a
received. PathErr is received.
The sending of an RSVP PathErr with the Notify error code and The sending of an RSVP PathErr with the Notify error code and the
"Preferable P2MP-TE Tree Exists" sub-code to the ingress node "Preferable P2MP-TE Tree Exists" sub-code to the ingress node
notifies the ingress node of the existence of a preferable P2MP-TE notifies the ingress node of the existence of a preferable P2MP-TE
LSP tree and upon receiving this PathErr, the ingress node SHOULD LSP tree, and upon receiving this PathErr, the ingress node SHOULD
trigger re-optimization of the LSP using the MBB method with a trigger the reoptimization of the LSP, using the MBB method with a
different LSP-ID. different LSP-ID.
4.2. Sub-Group-Based Re-optimization Using Fragment Identifier 4.2. Sub-Group-Based Reoptimization Using Fragment Identifier
It might be preferable, as per [RFC4875], to re-optimize the entire It might be preferable, as per [RFC4875], to reoptimize 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-LSPs (Section 14.1
"Make-before-Break") or to re-optimize individual or group of S2L ("Make-before-Break") in [RFC4875]) or to reoptimize an individual
sub-LSP(s) i.e. individual or group of destination(s) (Section 14.2 S2L sub-LSP or a group of S2L sub-LSPs, i.e., an individual
"Sub-Group-Based Re-Optimization" in [RFC4875]), both using the same destination or a group of destinations (Section 14.2
LSP-ID. For loosely routed S2L sub-LSPs, this can be achieved by ("Sub-Group-Based Re-Optimization") in [RFC4875]), both using the
using the procedures defined in [RFC4736] to re-optimize one or more same LSP-ID. For loosely routed S2L sub-LSPs, this can be achieved
S2L sub-LSP(s) of the P2MP-TE LSP. by using the procedures defined in [RFC4736] to reoptimize one or
more S2L sub-LSPs 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
point LSR may send a PathErr with the Notify error code (value 25) midpoint LSR may send a PathErr with Notify error code 25 and
and "Preferable Path Exists" (sub-code 6) containing a list of S2L sub-code 6 ("Preferable Path Exists") containing a list of S2L
sub-LSPs transiting through the LSR using an S2L sub-LSP descriptor sub-LSPs transiting through the LSR using an S2L sub-LSP descriptor
list to notify the 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 The S2L_SUB_LSP_FRAG object defined in this document is optional,
Information"), when a Path message is not large enough to fit all S2L with the following exceptions:
sub-LSPs in the descriptor list, an LSR may semantically fragment the
message. In this case, the LSR MUST add the S2L_SUB_LSP_FRAG Object
defined in this document in the S2L sub-LSP descriptor to be able to
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. o As per [RFC4875], Section 5.2.3 ("Transit Fragmentation of Path
However, a node MUST add the S2L_SUB_LSP_FRAG Object for each State Information"), when a Path message is not large enough to
fragment in S2L sub-LSP descriptor when the RSVP message needs to be fit all S2L sub-LSPs in the descriptor list, an LSR may
fragmented. semantically fragment the message. In this case, the LSR MUST add
the S2L_SUB_LSP_FRAG object defined in this document for each
fragment in the S2L sub-LSP descriptor to be able to rebuild the
list from the received fragments that may arrive out of order.
A mid-point LSR SHOULD wait to accumulate all S2L sub-LSPs before o In any other situation where an RSVP message needs to be
attempting to re-evaluate preferable path when a Path message for fragmented, an LSR MUST add the S2L_SUB_LSP_FRAG object for each
"Path Re-evaluation Request" is received with S2L_SUB_LSP_FRAG fragment in the S2L sub-LSP descriptor.
Object. If a mid-point LSR does not receive all fragments of the
Path message (for example, when fragments are lost) within a A midpoint LSR SHOULD wait to accumulate all S2L sub-LSPs before
configurable time interval, it SHOULD trigger re-evaluation of all attempting to re-evaluate a preferable path when a Path message for
S2L sub-LSPs of the P2MP-TE LSP transiting on the node. A mid-point "Path Re-evaluation Request" is received with the S2L_SUB_LSP_FRAG
LSR MUST receive at least one fragment of the Path message to trigger object. If a midpoint LSR does not receive all fragments of the Path
this behaviour. message (for example, when fragments are lost) within a configurable
time interval, it SHOULD trigger the re-evaluation of all S2L
sub-LSPs of the P2MP-TE LSP transiting on the node. A midpoint LSR
MUST receive at least one fragment of the Path message to trigger
this behavior.
An ingress node SHOULD wait to accumulate all S2L sub-LSPs before An ingress node SHOULD wait to accumulate all S2L sub-LSPs before
attempting to trigger re-optimization when a PathErr with Notify attempting to trigger reoptimization when a PathErr with the Notify
error code and "Preferable Path Exists" sub-code is received with a error code and the "Preferable Path Exists" sub-code is received with
S2L_SUB_LSP_FRAG Object. If an ingress node does not receive all an 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) within a configurable time interval, it SHOULD trigger re- lost) within a configurable time interval, it SHOULD trigger the
optimization of all S2L sub-LSPs of the P2MP-TE LSP transiting on the reoptimization of all S2L sub-LSPs of the P2MP-TE LSP transiting on
mid-point node that had sent the PathErr message. An ingress node the midpoint node that had sent the PathErr message. An ingress node
MUST receive at least one fragment of the PathErr message to trigger MUST receive at least one fragment of the PathErr message to trigger
this behaviour. this behavior.
The S2L_SUB_LSP_FRAG Object defined in this document has a wider The S2L_SUB_LSP_FRAG object defined in this document has a wider
applicability in addition to the P2MP-TE LSP re-optimization. It can applicability in addition to the P2MP-TE LSP reoptimization. It can
also be used (in Path and Resv messages) to setup a new P2MP-TE LSP, also be used (in Path and Resv messages) to set up a new P2MP-TE LSP
send other PathErr messages as well as Path Tear and Resv Tear and to 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 messages for a set of S2L sub-LSPs. This is outside the scope of
this document. this document.
5. Message and Object Definitions 5. Message and Object Definitions
5.1. 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 in the
defined in Attributes Flags TLV of the LSP_ATTRIBUTES Object Attribute Flags TLV of the LSP_ATTRIBUTES object [RFC5420] is defined
[RFC5420] as follows: by this document:
Bit Number (TBA1, to be assigned by IANA): P2MP-TE Tree Bit Number 14: "P2MP-TE Tree Re-evaluation 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]. using the message format defined in [RFC6510].
5.2. Preferable P2MP-TE Tree Exists Path Error Sub-code 5.2. "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 with Notify error tree exists, the following new sub-code for PathErr messages with
code 25 [RFC3209] is defined: Notify error code 25 [RFC3209] is defined by this document:
Sub-code (TBA2, to be assigned by IANA): Preferable P2MP-TE Tree Sub-code 13: "Preferable P2MP-TE Tree Exists" sub-code
Exists sub-code
When a preferable path for P2MP-TE LSP tree exists, the mid-point LSR When a preferable path for a P2MP-TE LSP tree exists, the midpoint
sends a solicited or unsolicited "Preferable P2MP-TE Tree Exists" LSR sends a solicited or unsolicited "Preferable P2MP-TE Tree Exists"
sub-code with PathErr with Notify error code 25 to the ingress node sub-code with a PathErr message with Notify error code 25 to the
of the P2MP-TE LSP. ingress node of the P2MP-TE LSP.
5.3. Fragment Identifier For S2L sub-LSP Descriptor 5.3. Fragment Identifier for S2L Sub-LSP Descriptor
The 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 semantically fragmented [RFC4875]. The RSVP message may need to be semantically fragmented
[RFC4875] due to large number of S2L sub-LSPs added in the descriptor [RFC4875] due to a large number of S2L sub-LSPs added in the
list, and such fragments may be received our of order. To be able to descriptor list, and such fragments may be received out of order. To
rebuild the fragmented S2L sub-LSP descriptor list correctly, the be able to rebuild the fragmented S2L sub-LSP descriptor list
following Object is defined to identify the fragments. correctly, the following object is defined to identify the fragments:
S2L_SUB_LSP_FRAG: Class-Num TBA3 by IANA
+---------------+---------------+---------------+---------------+ S2L_SUB_LSP_FRAG: Class Number 204
| Length (8 bytes) | Class-Num TBA3| C-Type 1 |
+---------------+---------------+---------------+---------------+
| Fragment ID | Fragments Tot | Fragment Num |
+---------------+---------------+---------------+---------------+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length (8 bytes) | Class Num 204 | C-Type 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Fragment ID | Fragments Tot.| Fragment Num. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fragment ID: 16-bit integer in the range of 1 to 65535. Fragment ID: 16-bit integer in the range of 1 to 65535.
This value is incremented for each new RSVP message that needs to This value is incremented for each new RSVP message that needs to
be semantically fragmented. The fragment ID is reset to 1 when it be semantically fragmented. The fragment ID is reset to 1 when it
reaches the maximum value of 65535. The scope of the fragment ID reaches the maximum value of 65535. The scope of the fragment ID
is limited to the RSVP message type (e.g. Path) carrying the is limited to the RSVP message type (e.g., Path) carrying the
fragment. In other words, fragment IDs do not have any fragment. In other words, fragment IDs do not have any
correlation between different RSVP message types (e.g. Path and correlation between different RSVP message types (e.g., Path and
PathErr). The receiver does not check to ensure if the PathErr). The receiver does not check to ensure that the
consecutive new RSVP messages (e.g. Path messages) are received consecutive new RSVP messages (e.g., Path messages) are received
with fragment IDs incremented by 1. with fragment IDs incremented by 1.
Fragments Total: 8-bit integer in the range of 1 to 255. Fragments Total: 8-bit integer in the range of 1 to 255.
This value indicates the number of fragments sent for the given This value indicates the number of fragments sent for the given
RSVP message. This value MUST be the same in all fragmented RSVP RSVP message. This value MUST be the same in all fragmented RSVP
messages with a common Fragment ID. messages with a common fragment ID.
Fragment Number: 8-bit integer in the range of 1 to 255. Fragment Number: 8-bit integer in the range of 1 to 255.
This value indicates the position of this fragment in the given This value indicates the position of this fragment in the given
RSVP message. RSVP message.
The format of an S2L sub-LSP descriptor message is as follows: The format of an S2L sub-LSP descriptor message is as follows:
<S2L sub-LSP descriptor> ::= <S2L sub-LSP descriptor> ::=
[ <S2L_SUB_LSP_FRAG> ] [ <S2L_SUB_LSP_FRAG> ]
<S2L_SUB_LSP> <S2L_SUB_LSP>
[ <P2MP SECONDARY_EXPLICIT_ROUTE> ] [ <P2MP SECONDARY_EXPLICIT_ROUTE> ]
The S2L_SUB_LSP_FRAG Object is added before adding the S2L_SUB_LSP The S2L_SUB_LSP_FRAG object is added before adding the S2L_SUB_LSP
Object in the semantically fragmented RSVP message. object in the semantically fragmented RSVP message.
6. Compatibility 6. Compatibility
The LSP_ATTRIBUTES Object has been defined in [RFC5420] and its
The LSP_ATTRIBUTES object has been defined in [RFC5420] and its
message formats in [RFC6510] with class numbers in the form 11bbbbbb, message formats in [RFC6510] with class numbers in the form 11bbbbbb,
which ensures compatibility with non-supporting nodes. Per which ensures compatibility with non-supporting nodes. Per
[RFC2205], nodes not supporting this extension will ignore the new [RFC2205], nodes not supporting this extension will ignore the new
flag defined for this Object in this document but forward it without flag defined for this object in this document and will forward it
modification. 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 this Object will ignore nodes. Per [RFC2205], nodes not supporting this object will ignore
the Object but forward it without modification. the object and will forward it without modification.
7. IANA Considerations 7. IANA Considerations
IANA is requested to administer assignment of new values for IANA has performed the actions described below.
namespace defined in this document and summarized in this section.
7.1. P2MP-TE Tree Re-evaluation Request Flag
IANA maintains a name space for RSVP-TE TE parameters "Resource
Reservation Protocol-Traffic Engineering (RSVP-TE) Parameters" (see
http://www.iana.org/assignments/rsvp-te-parameters). From the
registries in this name space "Attribute Flags", allocation of new
flag is requested (Section 5.1).
The following new flag is defined for the Attributes Flags TLV in the
LSP_ATTRIBUTES Object [RFC5420]. The numeric value is to be assigned
by IANA.
o P2MP-TE Tree Re-evaluation Request Flag: 7.1. "P2MP-TE Tree Re-evaluation Request" Flag
+--------+---------------+---------+---------+---------+-----------+ IANA maintains the "Resource Reservation Protocol-Traffic Engineering
| Bit No | Attribute | Carried | Carried | Carried | Reference | (RSVP-TE) Parameters" registry (see
| | Flag Name | in Path | in Resv | in RRO | | <http://www.iana.org/assignments/rsvp-te-parameters>). Per
| | | | | or ERO | | Section 5.1 of this document, IANA has registered a new flag in the
+--------+---------------+---------+---------+---------+-----------+ "Attribute Flags" registry. This new flag is defined for the
| TBA1 by| P2MP-TE Tree | Yes | No | No | This | Attribute Flags TLV in the LSP_ATTRIBUTES object [RFC5420].
| IANA | Re-evaluation | | | | document |
+--------+---------------+---------+---------+---------+-----------+
7.2. Preferable P2MP-TE Tree Exists Path Error Sub-code +-----+---------------+----------+----------+-----+-----+-----------+
| Bit | Name | Attribute| Attribute| RRO | ERO | Reference |
| No | | Flags | Flags | | | |
| | | Path | Resv | | | |
+-----+---------------+----------+----------+-----+-----+-----------+
| | P2MP-TE Tree | Yes | No | No | No | This |
| 14 | Re-evaluation | | | | | document |
| | Request | | | | | |
+-----+---------------+----------+----------+-----+-----+-----------+
IANA maintains a name space for RSVP protocol parameters "Resource 7.2. "Preferable P2MP-TE Tree Exists" Path Error Sub-code
Reservation Protocol (RSVP) Parameters" (see
http://www.iana.org/assignments/rsvp-parameters). From the
sub-registry "Sub-Codes - 25 Notify Error" in registry "Error Codes
and Globally-Defined Error Value Sub-Codes", allocation of a new
error code is requested (Section 5.2).
As defined in [RFC3209], the Error Code 25 in the ERROR SPEC Object IANA maintains the "Resource Reservation Protocol (RSVP) Parameters"
corresponds to PathErr with Notify error. This document adds a new registry (see <http://www.iana.org/assignments/rsvp-parameters>).
sub-code for this PathErr as follows: Per Section 5.2 of this document, IANA has registered a new error
code in the "Sub-Codes - 25 Notify Error" sub-registry of the "Error
Codes and Globally-Defined Error Value Sub-Codes" registry.
o Preferable P2MP-TE Tree Exists sub-code: As defined in [RFC3209], error code 25 in the ERROR_SPEC object
corresponds to a PathErr with the Notify error. This document adds a
new "Preferable P2MP-TE Tree Exists" sub-code for this PathErr as
follows:
+----------+--------------------+---------+---------+-----------+ +----------+--------------------+---------+---------+-----------+
| Sub-code | Sub-code | PathErr | PathErr | Reference | | Value | Description | PathErr | PathErr | Reference |
| value | Description | Code | Name | | | | | Code | Name | |
+----------+--------------------+---------+---------+-----------+ +----------+--------------------+---------+---------+-----------+
| TBA2 by | Preferable P2MP-TE | 25 | Notify | This | | 13 | Preferable P2MP-TE | 25 | Notify | This |
| IANA | Tree Exists | | Error | document | | | Tree Exists | | Error | document |
+----------+--------------------+---------+---------+-----------+ +----------+--------------------+---------+---------+-----------+
7.3. 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 the "Resource Reservation Protocol (RSVP) Parameters"
Reservation Protocol (RSVP) Parameters" (see registry (see <http://www.iana.org/assignments/rsvp-parameters>).
http://www.iana.org/assignments/rsvp-parameters). From the registry Per Section 5.3 of this document, IANA has registered a new class
"Class Names, Class Numbers, and Class Types", allocation of new number in the "Class Names, Class Numbers, and Class Types" registry.
Class-Num is requested (Section 5.3).
o S2L_SUB_LSP_FRAG Object: +-----------------+---------------------------+-----------------+
| Class Number | Class Name | Reference |
+-----------------+---------------------------+-----------------+
| 204 | S2L_SUB_LSP_FRAG | This document |
+-----------------+---------------------------+-----------------+
IANA has also created the "Class Types or C-Types - 204
S2L_SUB_LSP_FRAG" registry and populated it as follows:
+-----------------+---------------------------+-----------------+ +-----------------+---------------------------+-----------------+
| Class-Num value | Description | Reference | | Value | Description | Reference |
+-----------------+---------------------------+-----------------+ +-----------------+---------------------------+-----------------+
| TBA3 by IANA | S2L_SUB_LSP_FRAG | This document | | 1 | S2L_SUB_LSP_FRAG | This document |
+-----------------+---------------------------+-----------------+ +-----------------+---------------------------+-----------------+
8. 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 LSP ingress node of a P2MP-TE LSP to request the re-evaluation of the LSP
tree downstream of a node, and for a mid-point LSR to notify the tree downstream of a node and to allow a midpoint LSR to notify the
ingress node of the existence of a preferable tree by sending a ingress node of the existence of a preferable tree by sending a
PathErr. As per [RFC4736], in the case of a P2MP-TE LSP S2L sub-LSP PathErr message. As per [RFC4736], in the case of a P2MP-TE LSP S2L
spanning multiple domains, it may be desirable for a mid-point LSR to sub-LSP spanning multiple domains, it may be desirable for a midpoint
modify the RSVP PathErr message defined in this document to preserve LSR to modify the RSVP PathErr message to preserve confidentiality
confidentiality across domains. across domains.
This document also defines fragment identifier for the S2L sub-LSP This document also defines a fragment identifier for the S2L sub-LSP
descriptor when combining large number of S2L sub-LSPs in an RSVP descriptor when combining a large number of S2L sub-LSPs in an RSVP
message and the message needs to be semantically fragmented. The message and the message needs to be semantically fragmented. The
introduction of the fragment identifier, by itself, introduces no introduction of the fragment identifier, by itself, introduces no
additional information to signaling. For a general discussion on additional information to signaling. For a general discussion on
MPLS and GMPLS related security issues, see the MPLS/GMPLS security security issues related to MPLS and GMPLS, see the MPLS/GMPLS
framework [RFC5920]. security framework [RFC5920].
9. References 9. References
9.1. 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,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[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, DOI 10.17487/RFC2205,
September 1997, <http://www.rfc-editor.org/info/rfc2205>.
[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
Tunnels", RFC 3209, December 2001. Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<http://www.rfc-editor.org/info/rfc3209>.
[RFC4736] Vasseur, JP., Ikejiri, Y. and Zhang, R, "Reoptimization of [RFC4736] Vasseur, JP., Ed., Ikejiri, Y., and R. Zhang,
Multiprotocol Label Switching (MPLS) Traffic Engineering "Reoptimization of Multiprotocol Label Switching (MPLS)
(TE) Loosely Routed Label Switched Path (LSP)", RFC 4736, Traffic Engineering (TE) Loosely Routed Label Switched
November 2006. Path (LSP)", RFC 4736, DOI 10.17487/RFC4736,
November 2006, <http://www.rfc-editor.org/info/rfc4736>.
[RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, [RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
"Extensions to Resource Reservation Protocol Traffic Yasukawa, Ed., "Extensions to Resource Reservation
Engineering (RSVP-TE) for Point-to-Multipoint TE Label Protocol - Traffic Engineering (RSVP-TE) for
Switched Paths (LSPs)", RFC 4875, May 2007. Point-to-Multipoint TE Label Switched Paths (LSPs)",
RFC 4875, DOI 10.17487/RFC4875, May 2007,
<http://www.rfc-editor.org/info/rfc4875>.
[RFC5420] Farrel, A., Papadimitriou, D., Vasseur, JP., and Ayyangar, [RFC5420] Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and A.
A., "Encoding of Attributes for MPLS LSP Establishment Ayyangarps, "Encoding of Attributes for MPLS LSP
Using Resource Reservation Protocol Traffic Engineering Establishment Using Resource Reservation Protocol Traffic
(RSVP-TE)", RFC 5420, February 2009. Engineering (RSVP-TE)", RFC 5420, DOI 10.17487/RFC5420,
February 2009, <http://www.rfc-editor.org/info/rfc5420>.
9.2. Informative References 9.2. Informative References
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
(GMPLS) Signaling Resource ReserVation Protocol-Traffic Switching (GMPLS) Signaling Resource ReserVation
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, DOI 10.17487/RFC3473, January 2003,
<http://www.rfc-editor.org/info/rfc3473>.
[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. DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS [RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010. Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
<http://www.rfc-editor.org/info/rfc5920>.
[RFC6510] Berger, L. and G. Swallow, "Resource Reservation Protocol [RFC6510] Berger, L. and G. Swallow, "Resource Reservation Protocol
(RSVP) Message Formats for Label Switched Path (LSP) (RSVP) Message Formats for Label Switched Path (LSP)
Attributes Objects", RFC 6510, February 2012. Attributes Objects", RFC 6510, DOI 10.17487/RFC6510,
February 2012, <http://www.rfc-editor.org/info/rfc6510>.
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, Vishnu Pavan Beeram Villamizar, Dimitri Papadimitriou, Nobo Akiya, Vishnu Pavan Beeram,
and Joel M. Halpern for reviewing this document and providing many and Joel M. Halpern for reviewing this document and providing many
useful comments and suggestions. The authors would also like to useful comments and suggestions. The authors would also like to
thank Ling Zeng with Cisco Systems for implementing mechanisms thank Ling Zeng with Cisco Systems for implementing the mechanisms
defined in this document. A special thanks to Adrian Farrel for his defined in this document. A special thanks to Adrian Farrel for his
thorough review of this document. thorough review of this document.
Author's Addresses Authors' Addresses
Tarek Saad (editor) Tarek Saad (editor)
Cisco Systems Cisco Systems, Inc.
EMail: tsaad@cisco.com Email: tsaad@cisco.com
Rakesh Gandhi (editor) Rakesh Gandhi (editor)
Cisco Systems Cisco Systems, Inc.
EMail: rgandhi@cisco.com Email: rgandhi@cisco.com
Zafar Ali Zafar Ali
Cisco Systems Cisco Systems, Inc.
EMail: zali@cisco.com Email: zali@cisco.com
Robert H. Venator Robert H. Venator
Defense Information Systems Agency Defense Information Systems Agency
EMail: robert.h.venator.civ@mail.mil Email: robert.h.venator.civ@mail.mil
Yuji Kamite Yuji Kamite
NTT Communications Corporation NTT Communications Corporation
EMail: y.kamite@ntt.com Email: y.kamite@ntt.com
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