draft-ietf-mpls-mp-ldp-reqs-08.txt   rfc6348.txt 
MPLS J. Le Roux, Ed. Internet Engineering Task Force (IETF) J. Le Roux, Ed.
Internet-Draft T. Morin, Ed. Request for Comments: 6348 T. Morin, Ed.
Intended status: Historic France Telecom - Orange Category: Historic France Telecom - Orange
Expires: November 27, 2011 May 26, 2011 ISSN: 2070-1721 September 2011
Requirements for Point-To-Multipoint Extensions to the Label Requirements for Point-to-Multipoint Extensions
Distribution Protocol to the Label Distribution Protocol
draft-ietf-mpls-mp-ldp-reqs-08
Abstract Abstract
This document lists a set of functional requirements that served as This document lists a set of functional requirements that served as
input to the design of Label Distribution Protocol (LDP) extensions input to the design of Label Distribution Protocol (LDP) extensions
for setting up point-to-multipoint (P2MP) Label Switched Paths (LSP), for setting up point-to-multipoint (P2MP) Label Switched Paths (LSP),
in order to deliver point-to-multipoint applications over a Multi in order to deliver point-to-multipoint applications over a
Protocol Label Switching (MPLS) infrastructure. Multiprotocol Label Switching (MPLS) infrastructure.
Status of this Memo This work was overtaken by the protocol solution developed by the
MPLS working group, but that solution did not closely follow the
requirements documented here. This document is published as a
historic record of the ideas and requirements that shaped the
protocol work.
This Internet-Draft is submitted in full conformance with the Status of This Memo
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is not an Internet Standards Track specification; it is
Task Force (IETF). Note that other groups may also distribute published for the historical record.
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document defines a Historic Document for the Internet community.
and may be updated, replaced, or obsoleted by other documents at any This document is a product of the Internet Engineering Task Force
time. It is inappropriate to use Internet-Drafts as reference (IETF). It represents the consensus of the IETF community. It has
material or to cite them other than as "work in progress." received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
This Internet-Draft will expire on November 27, 2011. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6348.
Copyright Notice Copyright Notice
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document authors. All rights reserved. document authors. All rights reserved.
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than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Contributing Authors . . . . . . . . . . . . . . . . . . . 4 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Definitions . . . . . . . . . . . . . . . . . . . . . . . 5 1.3. Context and Motivations . . . . . . . . . . . . . . . . . 6
1.4. Context and Motivations . . . . . . . . . . . . . . . . . 6 1.4. Document Scope . . . . . . . . . . . . . . . . . . . . . . 7
1.5. Document Scope . . . . . . . . . . . . . . . . . . . . . . 7
2. Requirements Overview . . . . . . . . . . . . . . . . . . . . 7 2. Requirements Overview . . . . . . . . . . . . . . . . . . . . 7
3. Application Scenario . . . . . . . . . . . . . . . . . . . . . 8 3. Application Scenario . . . . . . . . . . . . . . . . . . . . . 8
4. Detailed Requirements . . . . . . . . . . . . . . . . . . . . 9 4. Detailed Requirements . . . . . . . . . . . . . . . . . . . . 9
4.1. P2MP LSPs . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1. P2MP LSPs . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. P2MP LSP FEC . . . . . . . . . . . . . . . . . . . . . . . 9 4.2. P2MP LSP FEC . . . . . . . . . . . . . . . . . . . . . . . 10
4.3. P2MP LDP Routing . . . . . . . . . . . . . . . . . . . . . 10 4.3. P2MP LDP Routing . . . . . . . . . . . . . . . . . . . . . 10
4.4. Setting Up, Tearing Down and Modifying P2MP LSPs . . . . . 10 4.4. Setting Up, Tearing Down, and Modifying P2MP LSPs . . . . 10
4.5. Label Advertisement . . . . . . . . . . . . . . . . . . . 10 4.5. Label Advertisement . . . . . . . . . . . . . . . . . . . 10
4.6. Data Duplication . . . . . . . . . . . . . . . . . . . . . 10 4.6. Data Duplication . . . . . . . . . . . . . . . . . . . . . 11
4.7. Detecting and Avoiding Loops . . . . . . . . . . . . . . . 11 4.7. Detecting and Avoiding Loops . . . . . . . . . . . . . . . 11
4.8. P2MP LSP Re-routing . . . . . . . . . . . . . . . . . . . 11 4.8. P2MP LSP Rerouting . . . . . . . . . . . . . . . . . . . . 11
4.9. Support for Multi-Access Networks . . . . . . . . . . . . 12 4.9. Support for Multi-Access Networks . . . . . . . . . . . . 12
4.10. Support for Encapsulation in P2P and P2MP TE Tunnels . . . 12 4.10. Support for Encapsulation in P2P and P2MP TE Tunnels . . . 12
4.11. Label Spaces . . . . . . . . . . . . . . . . . . . . . . . 13 4.11. Label Spaces . . . . . . . . . . . . . . . . . . . . . . . 13
4.12. IPv4/IPv6 Support . . . . . . . . . . . . . . . . . . . . 13 4.12. IPv4/IPv6 Support . . . . . . . . . . . . . . . . . . . . 13
4.13. Multi-Area/AS LSPs . . . . . . . . . . . . . . . . . . . . 13 4.13. Multi-Area/AS LSPs . . . . . . . . . . . . . . . . . . . . 13
4.14. OAM . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.14. OAM . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.15. Graceful Restart and Fault Recovery . . . . . . . . . . . 13 4.15. Graceful Restart and Fault Recovery . . . . . . . . . . . 14
4.16. Robustness . . . . . . . . . . . . . . . . . . . . . . . . 13 4.16. Robustness . . . . . . . . . . . . . . . . . . . . . . . . 14
4.17. Scalability . . . . . . . . . . . . . . . . . . . . . . . 14 4.17. Scalability . . . . . . . . . . . . . . . . . . . . . . . 14
4.18. Backward Compatibility . . . . . . . . . . . . . . . . . . 14 4.18. Backward Compatibility . . . . . . . . . . . . . . . . . . 14
5. Shared Trees . . . . . . . . . . . . . . . . . . . . . . . . . 14 5. Shared Trees . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1. Requirements for MP2MP LSPs . . . . . . . . . . . . . . . 15 5.1. Requirements for MP2MP LSPs . . . . . . . . . . . . . . . 15
6. Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . 16 6. Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . 16
6.1. Performance . . . . . . . . . . . . . . . . . . . . . . . 16 6.1. Performance . . . . . . . . . . . . . . . . . . . . . . . 16
6.2. Complexity and Risks . . . . . . . . . . . . . . . . . . . 17 6.2. Complexity and Risks . . . . . . . . . . . . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 17 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . . 17 9.1. Normative References . . . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . . 18 9.2. Informative References . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 Contributing Authors . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
This document lists a set of functional requirements that served as This document lists a set of functional requirements that served as
input to the design of Label Distribution Protocol (LDP) extensions input to the design of Label Distribution Protocol (LDP) extensions
for setting up point-to-multipoint (P2MP) Label Switched Paths for setting up point-to-multipoint (P2MP) Label Switched Paths (LSP)
(LSP)[I-D.ietf-mpls-ldp-p2mp], in order to deliver point-to- [MLDP], in order to deliver point-to-multipoint applications over a
multipoint applications over a Multi-Protocol Label Switching (MPLS) Multiprotocol Label Switching (MPLS) infrastructure.
infrastructure. It is published with Historic status with the
perspective of documenting the work done.
The document is structured as follows:
o Section 2 is an overview of the requirements;
o Section 3 illustrates an application scenario;
o Section 4 addresses detailed requirements for P2MP LSPs;
o Section 5 finally discusses requirements for shared trees and
MultiPoint-to-MultiPoint (MP2MP) LSPs.
1.1. Contributing Authors
The following people contributed to the text and content of this
document:
o Shane Amante, Level 3 Communications, LLC This work was overtaken by the protocol solution developed by the
MPLS working group and documented in [MLDP]. That solution did not
closely follow the requirements documented here, and it was
recognized that this document had served its purpose in driving
discussions of how the solution should be designed. At this point,
no further action is planned to update this document in line with the
protocol solution, and this document is published simply as a
historic record of the ideas and requirements that shaped the
protocol work.
o Luyuan Fang, Cisco Systems The document is structured as follows:
o Yuji Kamite, NTT Communications Corporation o Section 2 is an overview of the requirements.
o Jean-Louis Le Roux, France Telecom - Orange o Section 3 illustrates an application scenario.
o Thomas Morin, France Telecom - Orange o Section 4 addresses detailed requirements for P2MP LSPs.
o Vincent Parfait, France Telecom - Orange, Orange Business Services o Section 5 discusses requirements for shared trees and multipoint-
to-multipoint (MP2MP) LSPs.
o Lei Wang, Telenor o Section 6 presents criteria against which a solution can be
evaluated.
1.2. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", This document is a historic requirements document. To clarify
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this statement of requirements, key words are used as follows. The key
document are to be interpreted as described in [RFC2119]. 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].
1.3. Definitions 1.2. Definitions
1.3.1. Acronyms 1.2.1. Acronyms
P2P: Point-To-Point P2P: Point-to-Point
MP2P: Multipoint-to-Point MP2P: Multipoint-to-Point
P2MP: Point-to-Multipoint
P2MP: Point-To-MultiPoint MP2MP: Multipoint-to-Multipoint
MP2MP: MultiPoint-To-Multipoint
LSP: Label Switched Path LSP: Label Switched Path
LSR: Label Switching Router LSR: Label Switching Router
PE: Provider Edge router PE: Provider Edge
P: Provider router P: Provider
IGP: Interior Gateway Protocol IGP: Interior Gateway Protocol
AS: Autonomous System AS: Autonomous System
1.3.2. Terminology 1.2.2. Terminology
The reader is assumed to be familiar with the terminology in The reader is assumed to be familiar with the terminology in
[RFC3031], [RFC5036], and [RFC4026]. [RFC3031], [RFC5036], and [RFC4026].
Ingress LSR: Ingress LSR:
Router acting as a sender of an LSP Router acting as a sender of an LSP
Egress LSR: Egress LSR:
Router acting as a receiver of an LSP Router acting as a receiver of an LSP
P2P LSP: P2P LSP:
An LSP that has one unique Ingress LSR and one unique Egress LSR An LSP that has one unique Ingress LSR and one unique Egress LSR
MP2P LSP: MP2P LSP:
An LSP that has one or more Ingress LSRs and one unique Egress LSR An LSP that has one or more Ingress LSRs and one unique Egress LSR
P2MP LSP: P2MP LSP:
An LSP that has one unique Ingress LSR and one or more Egress LSRs An LSP that has one unique Ingress LSR and one or more Egress LSRs
MP2MP LSP: MP2MP LSP:
An LSP that as one or more Leaf LSRs acting indifferently as An LSP that has one or more Leaf LSRs acting indifferently as
Ingress or Egress LSR Ingress or Egress LSR
Leaf LSR: Leaf LSR:
An Egress LSR of a P2MP LSP or an Ingress/Egress LSR of a MP2MP An Egress LSR of a P2MP LSP or an Ingress/Egress LSR of an MP2MP
LSP LSP
Transit LSR: Transit LSR:
An LSR of a P2MP or MP2MP LSP that has one or more Downstream LSRs An LSR of a P2MP or MP2MP LSP that has one or more downstream LSRs
Branch LSR: Branch LSR:
An LSR of a P2MP or MP2MP LSP that has more than one downstream An LSR of a P2MP or MP2MP LSP that has more than one downstream
LSR LSR
Bud LSR: Bud LSR:
An LSR of a P2MP or MP2MP LSP that is an egress but also has one An LSR of a P2MP or MP2MP LSP that is an Egress but also has one
or more directly connected downstream LSR(s) or more directly connected downstream LSR(s)
P2MP tree: P2MP tree:
The ordered set of LSRs and links that comprise the path of a P2MP The ordered set of LSRs and links that comprise the path of a P2MP
LSP from its ingress LSR to all of its egress LSRs. LSP from its Ingress LSR to all of its Egress LSRs.
1.4. Context and Motivations 1.3. Context and Motivations
LDP [RFC5036] has been deployed for setting up point-to-point (P2P) LDP [RFC5036] has been deployed for setting up point-to-point (P2P)
and multipoint-to-point (MP2P) LSPs, in order to offer point-to-point and multipoint-to-point (MP2P) LSPs, in order to offer point-to-point
services in MPLS backbones. services in MPLS backbones.
There are emerging requirements for supporting delivery of point-to- There are emerging requirements for supporting delivery of point-to-
multipoint applications in MPLS backbones, such as those defined in multipoint applications in MPLS backbones, such as those defined in
[RFC4834] and [RFC5501]. [RFC4834] and [RFC5501].
For various reasons, including consistency with P2P applications, and For various reasons, including consistency with P2P applications, and
taking full advantages of MPLS network infrastructure, it would be taking full advantages of MPLS network infrastructure, it would be
highly desirable to use MPLS LSPs for the delivery of multicast highly desirable to use MPLS LSPs for the delivery of multicast
traffic. This could be implemented by setting up a group of P2P or traffic. This could be implemented by setting up a group of P2P or
MP2P LSPs, but such an approach may be inefficient since it would MP2P LSPs, but such an approach may be inefficient since it would
result in data replication at the ingress LSR and duplicate data result in data replication at the Ingress LSR and duplicate data
traffic within the network. Hence new mechanisms are required that traffic within the network.
would allow traffic from an Ingress LSR to be efficiently delivered
to a number of Egress LSRs in an MPLS backbone on a point-to-
multipoint LSP (P2MP LSP), avoiding duplicate copies of a packet on a
given link and with MPLS traffic replication at some Branch LSRs.
RSVP-TE extensions for setting up Point-To-Multipoint Traffic Hence, new mechanisms are required that would allow traffic from an
Engineered LSPs (P2MP TE LSPs), have been defined in [RFC4875]. They Ingress LSR to be efficiently delivered to a number of Egress LSRs in
meet requirements expressed in [RFC4461]. This approach is useful, an MPLS backbone on a point-to-multipoint LSP (P2MP LSP), avoiding
in network environments where P2MP Traffic Engineering capabilities duplicate copies of a packet on a given link and relying on MPLS
are needed (Optimization, QoS, Fast recovery). traffic replication at some Branch LSRs.
However for operators who want to support point-to-multipoint traffic Resource Reservation Protocol - Traffic Engineering (RSVP-TE)
delivery on an MPLS backbone, without Traffic Engineering needs, and extensions for setting up point-to-multipoint Traffic Engineered LSPs
who have already deployed LDP for P2P traffic, an interesting and (P2MP TE LSPs) have been defined in [RFC4875]. They meet
useful approach would be to rely on LDP extensions in order to setup requirements expressed in [RFC4461]. This approach is useful in
point-to-multipoint (P2MP) LSPs. This would bring consistency with network environments where P2MP Traffic Engineering capabilities are
P2P MPLS applications and would ease the delivery of point-to- needed (optimization, QoS, fast recovery).
multipoint services in an MPLS backbone.
1.5. Document Scope However, for operators who want to support point-to-multipoint
traffic delivery on an MPLS backbone, without Traffic Engineering
needs, and who have already deployed LDP for P2P traffic, an
interesting and useful approach would be to rely on LDP extensions in
order to set up point-to-multipoint (P2MP) LSPs. This would bring
consistency with P2P MPLS applications and would ease the delivery of
point-to-multipoint services in an MPLS backbone.
1.4. Document Scope
This document focuses on the LDP approach for setting up P2MP LSPs. This document focuses on the LDP approach for setting up P2MP LSPs.
It lists a detailed set of requirements for P2MP extensions to LDP, It lists a detailed set of requirements for P2MP extensions to LDP,
so as to deliver P2MP traffic over a LDP-enabled MPLS infrastructure. so as to deliver P2MP traffic over an LDP-enabled MPLS
The original intent was that these requirements should be used as infrastructure. The original intent was that these requirements
guidelines when specifying LDP extensions. should be used as guidelines when specifying LDP extensions.
Note that generic requirements for P2MP extensions to MPLS are out of Note that generic requirements for P2MP extensions to MPLS are out of
the scope of this document. Rather this document describes solution the scope of this document. Rather, this document describes
specific requirements related to LDP extensions in order to set up solution-specific requirements related to LDP extensions in order to
P2MP LSPs. set up P2MP LSPs.
Note also that other mechanisms could be used for setting up P2MP Note also that other mechanisms could be used for setting up P2MP
LSPs, such as for instance PIM extensions, but these are out of the LSPs (for instance, PIM extensions), but these are out of the scope
scope of this document. The objective is not to compare these of this document. The objective is not to compare these mechanisms
mechanisms but rather to focus on the requirements for an LDP but rather to focus on the requirements for an LDP extension
extension approach. approach.
2. Requirements Overview 2. Requirements Overview
The P2MP LDP mechanism MUST support setting up P2MP LSPs, i.e. LSPs The P2MP LDP mechanism MUST support setting up P2MP LSPs, i.e., LSPs
with one Ingress LSR and one or more Egress LSRs, with traffic with one Ingress LSR and one or more Egress LSRs, with traffic
replication at some Branch LSRs. replication at some Branch LSRs.
The P2MP LDP mechanism MUST allow the addition or removal of leaves The P2MP LDP mechanism MUST allow the addition or removal of leaves
associated with a P2MP LSP. associated with a P2MP LSP.
The P2MP LDP mechanism MUST co-exist with current LDP mechanisms and The P2MP LDP mechanism MUST coexist with current LDP mechanisms and
inherit its capability sets from [RFC5036]. It is of paramount inherit its capability sets from [RFC5036]. It is of paramount
importance that the P2MP LDP mechanism MUST NOT impede the operation importance that the P2MP LDP mechanism MUST NOT impede the operation
of existing P2P/MP2P LDP LSPs. Also the P2MP LDP mechanism MUST co- of existing P2P/MP2P LDP LSPs. Also, the P2MP LDP mechanism MUST
exist with P2P and P2MP RSVP-TE mechanisms [RFC3209], [RFC4875]. It coexist with P2P and P2MP RSVP-TE mechanisms [RFC3209] [RFC4875]. It
is of paramount importance that the P2MP LDP mechanism MUST NOT is of paramount importance that the P2MP LDP mechanism MUST NOT
impede the operation of existing P2P and P2MP RSVP-TE LSPs. impede the operation of existing P2P and P2MP RSVP-TE LSPs.
The P2MP LDP mechanism MAY also allow setting up multipoint-to- The P2MP LDP mechanism MAY also allow setting up multipoint-to-
multipoint (MP2MP) LSPs connecting a group of Leaf LSRs acting multipoint (MP2MP) LSPs connecting a group of Leaf LSRs acting
indifferently as Ingress LSR or Egress LSR. This may allow a indifferently as Ingress LSR or Egress LSR. This may allow a
reduction in the amount of LDP state that needs to be maintained by a reduction in the amount of LDP state that needs to be maintained by
LSR. an LSR.
3. Application Scenario 3. Application Scenario
Figure 1 below illustrates an LDP enabled MPLS provider network, used Figure 1 below illustrates an LDP-enabled MPLS provider network, used
to carry both unicast and multicast traffic of VPN customers to carry both unicast and multicast traffic of VPN customers
following for instance the architecture defined in following, for instance, the architecture defined in [MVPN] for BGP/
[I-D.ietf-l3vpn-2547bis-mcast] for BGP/MPLS VPNs, or the one defined MPLS VPNs or the one defined in [VPLS-MCAST].
in [I-D.ietf-l2vpn-vpls-mcast].
In this example, a set of MP2P LDP LSPs are setup between Provider In this example, a set of MP2P LDP LSPs is set up between Provider
Edge (PE) routers to carry unicast VPN traffic within the MPLS Edge (PE) routers to carry unicast VPN traffic within the MPLS
backbone. backbone (not represented in Figure 1).
And in this example a set of P2MP LDP LSPs are setup between PE In this example, a set of P2MP LDP LSPs is set up between PE routers
routers acting as Ingress LSRs and PE routers acting as Egress LSRs, acting as Ingress LSRs and PE routers acting as Egress LSRs, so as to
so as to support multicast VPN traffic delivery within the MPLS support multicast VPN traffic delivery within the MPLS backbone.
backbone.
For instance, a P2MP LDP LSP is setup between Ingress LSR PE1 and For instance, a P2MP LDP LSP is set up between Ingress LSR PE1 and
Egress LSRs PE2, PE3, and PE4. It is used to transport multicast Egress LSRs PE2, PE3, and PE4. It is used to transport multicast
traffic from PE1 to PE2, PE3 and PE4. P1 is a Branch LSR, it traffic from PE1 to PE2, PE3, and PE4. P1 is a Branch LSR; it
replicates MPLS traffic sent by PE1 to P2, P3 and PE2. P2 and P3 are replicates MPLS traffic sent by PE1 to P2, P3, and PE2. P2 and P3
non-branch transit LSRs, they forward MPLS traffic sent by P1 to PE3 are non-Branch Transit LSRs; they forward MPLS traffic sent by P1 to
and PE4 respectively. PE3 and PE4, respectively.
PE1 PE1
*| *** P2MP LDP LSP *| *** P2MP LDP LSP
*|***** *|*****
P1-----PE2 P1-----PE2
*/ \* */ \*
*/ \* */ \*
*****/ \****** *****/ \******
PE3----P2 P3----PE4 PE3----P2 P3----PE4
| | | |
| | | |
| | | |
PE5 PE6 PE5 PE6
Figure 1: P2MP LSP from PE1 to PE2, PE3, PE4. Figure 1: P2MP LSP from PE1 to PE2, PE3, PE4
If later there are new receivers attached to PE5 and PE6, then PE5 If later there are new receivers attached to PE5 and PE6, then PE5
and PE6 join the P2MP LDP LSP. P2 and P3 become Branch LSRs and and PE6 join the P2MP LDP LSP. P2 and P3 become Branch LSRs and
replicate traffic received from P1, to PE3 and PE5, and to PE4 and replicate traffic received from P1 to PE3 and PE5 and to PE4 and PE6,
PE6 respectively (see Figure 2 below). respectively (see Figure 2 below).
PE1 PE1
*| *** P2MP LDP LSP *| *** P2MP LDP LSP
*|***** *|*****
P1-----PE2 P1-----PE2
*/ \* */ \*
*/ \* */ \*
*****/ \****** *****/ \******
PE3----P2 P3----PE4 PE3----P2 P3----PE4
*| |* *| |*
*| |* *| |*
*| |* *| |*
PE5 PE6 PE5 PE6
Figure 2: Attachment of PE5 and PE6. Figure 2: Attachment of PE5 and PE6
The above example is provided for the sake of illustration. Note The above example is provided for the sake of illustration. Note
that P2MP LSPs ingress and egress LSRs may not necessarily be PE that P2MP LSPs Ingress and Egress LSRs may not necessarily be PE
routers. Also branch LSRs may not necessarily be P routers. routers. Also, Branch LSRs may not necessarily be P routers.
4. Detailed Requirements 4. Detailed Requirements
4.1. P2MP LSPs 4.1. P2MP LSPs
The P2MP LDP mechanism MUST support setting up P2MP LSPs. Data plane The P2MP LDP mechanism MUST support setting up P2MP LSPs. Data plane
aspects related to P2MP LSPs are those already defined in [RFC4461]. aspects related to P2MP LSPs are those already defined in [RFC4461].
That is, a P2MP LSP has one Ingress LSR and one or more Egress LSRs. That is, a P2MP LSP has one Ingress LSR and one or more Egress LSRs.
Traffic sent by the Ingress LSR is received by all Egress LSRs. The Traffic sent by the Ingress LSR is received by all Egress LSRs. The
specific aspects related to P2MP LSPs is the action required at a specific aspect related to P2MP LSPs is the action required at a
Branch LSR, where data replication occurs. Incoming labelled data is Branch LSR, where data replication occurs. Incoming labeled data is
appropriately replicated to several outgoing interfaces which may use appropriately replicated to several outgoing interfaces, which may
different labels. use different labels.
An LSR SHOULD NOT send more than one copy of a packet on any given An LSR SHOULD NOT send more than one copy of a packet on any given
link of a P2MP LSP. Exceptions to this are mentioned in Section 4.9 link of a P2MP LSP. Exceptions to this are mentioned in Sections 4.9
and Section 4.18. and 4.18.
A P2MP LSP MUST be identified by a constant and unique identifier A P2MP LSP MUST be identified by a constant and unique identifier
within the whole LDP domain, whatever the number of leaves, which may within the whole LDP domain, whatever the number of leaves, which may
vary dynamically. This identifier will be used so as to add/remove vary dynamically. This identifier will be used so as to add/remove
leaves to/from the P2MP tree. leaves to/from the P2MP tree.
4.2. P2MP LSP FEC 4.2. P2MP LSP FEC
As with P2P MPLS technology [RFC5036], traffic MUST be classified As with P2P MPLS technology [RFC5036], traffic MUST be classified
into a FEC in this P2MP extension. All packets which belong to a into a Forwarding Equivalence Class (FEC) in this P2MP extension.
particular P2MP FEC and which travel from a particular node MUST use All packets that belong to a particular P2MP FEC and that travel from
the same P2MP LSP. a particular node MUST use the same P2MP LSP.
If existing FECs cannot be used for this purpose, a new LDP FEC that If existing FECs cannot be used for this purpose, a new LDP FEC that
is suitable for P2MP forwarding MUST be specified. is suitable for P2MP forwarding MUST be specified.
4.3. P2MP LDP Routing 4.3. P2MP LDP Routing
As with P2P and MP2P LDP LSPs, the P2MP LDP mechanism MUST support As with P2P and MP2P LDP LSPs, the P2MP LDP mechanism MUST support
hop-by-hop LSP routing. P2MP LDP-based routing SHOULD rely upon the hop-by-hop LSP routing. P2MP LDP-based routing SHOULD rely upon the
information maintained in LSR Routing Information Bases (RIB). information maintained in LSR Routing Information Bases (RIBs).
It is RECOMMENDED that the P2MP LSP routing rely upon the unicast It is RECOMMENDED that the P2MP LSP routing rely upon the unicast
route to the Ingress LSR to build a reverse path tree. route to the Ingress LSR to build a reverse path tree.
4.4. Setting Up, Tearing Down and Modifying P2MP LSPs 4.4. Setting Up, Tearing Down, and Modifying P2MP LSPs
The P2MP LDP mechanism MUST support the establishment, maintenance The P2MP LDP mechanism MUST support the establishment, maintenance,
and teardown of P2MP LSPs in a scalable manner. This MUST include and teardown of P2MP LSPs in a scalable manner. This MUST include
both the existence of a large amount of P2MP LSPs within a single both the existence of a large number of P2MP LSPs within a single
network and a large amount of leaf LSRs for a single P2MP LSP (see network and a large number of Leaf LSRs for a single P2MP LSP (see
also Section 4.17 for scalability considerations and figures). also Section 4.17 for scalability considerations and figures).
In order to scale well with a large number of leaves it is In order to scale well with a large number of leaves, it is
RECOMMENDED to follow a leaf-initiated P2MP LSP setup approach. For RECOMMENDED to follow a leaf-initiated P2MP LSP setup approach. For
that purpose, leaves will have to be aware of the P2MP LSP that purpose, leaves will have to be aware of the P2MP LSP
identifier. The ways a Leaf LSR discovers P2MP LSPs identifiers rely identifier. The ways a Leaf LSR discovers P2MP LSP identifiers rely
on the applications that will use P2MP LSPs, and are out of the scope on the applications that will use P2MP LSPs and are out of the scope
of this document. of this document.
The P2MP LDP mechanism MUST allow the dynamic addition and removal of The P2MP LDP mechanism MUST allow the dynamic addition and removal of
leaves to and from a P2MP LSP, without any restriction (provided leaves to and from a P2MP LSP, without any restriction (provided
there is network connectivity). It is RECOMMENDED that these there is network connectivity). It is RECOMMENDED that these
operations be leaf-initiated. These operations MUST NOT impact the operations be leaf-initiated. These operations MUST NOT impact the
data transfer (packet loss, duplication, delay) towards other leaves. data transfer (packet loss, duplication, delay) towards other leaves.
It is RECOMMENDED that these operations do not cause any additional It is RECOMMENDED that these operations do not cause any additional
processing except on the path from the added/removed Leaf LSR to the processing except on the path from the added/removed Leaf LSR to the
Branch LSR. Branch LSR.
skipping to change at page 11, line 5 skipping to change at page 11, line 12
advertisement mode. This is well suited to a leaf-initiated approach advertisement mode. This is well suited to a leaf-initiated approach
and is consistent with P2P/MP2P LDP operations. and is consistent with P2P/MP2P LDP operations.
Other advertisement modes MAY also be supported. Other advertisement modes MAY also be supported.
4.6. Data Duplication 4.6. Data Duplication
Data duplication refers to the receipt of multiple copies of a packet Data duplication refers to the receipt of multiple copies of a packet
by any leaf. Although this may be a marginal situation, it may also by any leaf. Although this may be a marginal situation, it may also
be detrimental for certain applications. Hence, data duplication be detrimental for certain applications. Hence, data duplication
SHOULD as much as possible be avoided, and limited to (hopefully SHOULD be avoided as much as possible and limited to (hopefully rare)
rare) transitory conditions. transitory conditions.
Note, in particular, that data duplication might occur if P2MP LSP Note, in particular, that data duplication might occur if P2MP LSP
rerouting is being performed (See also Section 4.8). rerouting is being performed (see also Section 4.8).
4.7. Detecting and Avoiding Loops 4.7. Detecting and Avoiding Loops
The P2MP LDP extension MUST have a mechanism to detect routing loops. The P2MP LDP extension MUST have a mechanism to detect routing loops.
This MAY rely on extensions to the LDP Loop detection mechanism This MAY rely on extensions to the LDP loop detection mechanism
defined in [RFC5036]. A loop detection mechanism MAY require defined in [RFC5036]. A loop detection mechanism MAY require
recording the set of LSRs traversed on the P2MP Tree. The P2MP loop recording the set of LSRs traversed on the P2MP tree. The P2MP loop
avoidance mechanism MUST NOT impact the scalability of the P2MP LDP avoidance mechanism MUST NOT impact the scalability of the P2MP LDP
solution. solution.
The P2MP LDP mechanism SHOULD have a mechanism to avoid routing loops The P2MP LDP mechanism SHOULD have a mechanism to avoid routing loops
in the data plane even during transient events. in the data plane even during transient events.
Furthermore, the P2MP LDP mechanism MUST avoid routing loops in the Furthermore, the P2MP LDP mechanism MUST avoid routing loops in the
data plane, that may trigger unexpected non-localized exponential data plane, which may trigger unexpected non-localized exponential
growth of traffic. growth of traffic.
4.8. P2MP LSP Re-routing 4.8. P2MP LSP Rerouting
The P2MP LDP mechanism MUST support the rerouting of a P2MP LSP in The P2MP LDP mechanism MUST support the rerouting of a P2MP LSP in
the following cases: the following cases:
o Network failure (link or node); o Network failure (link or node);
o A better path exists (e.g. new link, metric change); o A better path exists (e.g., new link or metric change); and
o Planned maintenance. o Planned maintenance.
Given that P2MP LDP routing should rely on the RIB, the achievement Given that P2MP LDP routing should rely on the RIB, the achievement
of the following requirements relies on the underlying routing of the following requirements relies on the underlying routing
protocols (IGP, etc.). protocols (IGP, etc.).
4.8.1. Rerouting upon Network Failure 4.8.1. Rerouting upon Network Failure
The P2MP LDP mechanism MUST allow for rerouting of a P2MP LSP in case The P2MP LDP mechanism MUST allow for rerouting of a P2MP LSP in case
of link or node failure(s), by relying upon update of the routes in of link or node failure(s) by relying upon update of the routes in
the RIB. The rerouting time SHOULD be minimized as much as possible the RIB. The rerouting time SHOULD be minimized as much as possible
so as to reduce traffic disruption. so as to reduce traffic disruption.
A mechanism MUST be defined to prevent constant P2MP LSP teardown and A mechanism MUST be defined to prevent constant P2MP LSP teardown and
rebuild which may be caused by the instability of a specific link/ rebuild, which may be caused by the instability of a specific link/
node in the network. This can rely on IGP dampening but may be node in the network. This can rely on IGP dampening but may be
completed by specific dampening at the LDP level. completed by specific dampening at the LDP level.
4.8.2. Rerouting on a Better Path 4.8.2. Rerouting on a Better Path
The P2MP LDP mechanism MUST allow for rerouting of a P2MP LSP in case The P2MP LDP mechanism MUST allow for rerouting of a P2MP LSP in case
a better path is created in the network, for instance as a result of a better path is created in the network, for instance, as a result of
a metric change, a link repair, or the addition of links or nodes. a metric change, a link repair, or the addition of links or nodes.
This will rely on update of the routes in the RIB. This will rely on update of the routes in the RIB.
4.8.3. Rerouting upon Planned Maintenance 4.8.3. Rerouting upon Planned Maintenance
The P2MP LDP mechanism MUST support planned maintenance operations. The P2MP LDP mechanism MUST support planned maintenance operations.
It MUST be possible to reroute a P2MP LSP before a link/node is It MUST be possible to reroute a P2MP LSP before a link/node is
deactivated for maintenance purposes. Traffic disruption and data deactivated for maintenance purposes. Traffic disruption and data
duplication SHOULD be minimized as much as possible during such duplication SHOULD be minimized as much as possible during such
planned maintenance. P2MP LSP rerouting upon planned maintenance MAY planned maintenance. P2MP LSP rerouting upon planned maintenance MAY
rely on a make before break procedure. rely on a make-before-break procedure.
4.9. Support for Multi-Access Networks 4.9. Support for Multi-Access Networks
The P2MP LDP mechanism SHOULD provide a way for a Branch LSR to send The P2MP LDP mechanism SHOULD provide a way for a Branch LSR to send
a single copy of the data onto an interface to a multi-access network a single copy of the data onto an interface to a multi-access network
(e.g. an Ethernet LAN) and reach multiple adjacent downstream nodes. (e.g., an Ethernet LAN) and reach multiple adjacent downstream nodes.
This requires that the same label be negotiated with all downstream This requires that the same label be negotiated with all downstream
LSRs for the LSP. LSRs for the LSP.
When there are several candidate upstream LSRs on an interface to a When there are several candidate upstream LSRs on an interface to a
multi-access LAN, the P2MP LDP mechanism SHOULD provide a way for all multi-access LAN, the P2MP LDP mechanism SHOULD provide a way for all
downstream LSRs of a given P2MP LSP to select the same upstream LSR, downstream LSRs of a given P2MP LSP to select the same upstream LSR,
so as to avoid traffic replication. In addition, the P2MP LDP so as to avoid traffic replication. In addition, the P2MP LDP
mechanism SHOULD allow for an efficient balancing of a set of P2MP mechanism SHOULD allow for an efficient balancing of a set of P2MP
LSPs among a set of candidate upstream LSRs on a LAN interface. LSPs among a set of candidate upstream LSRs on a LAN interface.
skipping to change at page 13, line 21 skipping to change at page 13, line 28
separate P2P and P2MP LDP sessions. separate P2P and P2MP LDP sessions.
4.12. IPv4/IPv6 Support 4.12. IPv4/IPv6 Support
The P2MP LDP mechanism MUST support the establishment of LDP sessions The P2MP LDP mechanism MUST support the establishment of LDP sessions
over both IPv4 and IPv6 control planes. over both IPv4 and IPv6 control planes.
4.13. Multi-Area/AS LSPs 4.13. Multi-Area/AS LSPs
The P2MP LDP mechanism MUST support the establishment of multi-area The P2MP LDP mechanism MUST support the establishment of multi-area
P2MP LSPs, i.e. LSPs whose leaves do not all reside in the same IGP P2MP LSPs, i.e., LSPs whose leaves do not all reside in the same IGP
area as the Ingress LSR. This SHOULD be possible without requiring area as the Ingress LSR. This SHOULD be possible without requiring
the advertisement of Ingress LSRs' addresses across IGP areas. the advertisement of Ingress LSRs' addresses across IGP areas.
The P2MP LDP mechanism MUST also support the establishment of The P2MP LDP mechanism MUST also support the establishment of
inter-AS P2MP LSPs, i.e. LSPs whose leaves do not all reside in the inter-AS P2MP LSPs, i.e., LSPs whose leaves do not all reside in the
same AS as the Ingress LSR. This SHOULD be possible without same AS as the Ingress LSR. This SHOULD be possible without
requiring the advertisement of Ingress LSRs' addresses across ASes. requiring the advertisement of Ingress LSRs' addresses across ASes.
4.14. OAM 4.14. OAM
LDP management tools ([RFC3815], etc.) will have to be enhanced to LDP management tools ([RFC3815], etc.) will have to be enhanced to
support P2MP LDP extensions. This may yield a new MIB module, which support P2MP LDP extensions. This may yield a new MIB module, which
may possibly be inherited from the LDP MIB. may possibly be inherited from the LDP MIB.
Built-in diagnostic tools MUST be defined to check the connectivity, Built-in diagnostic tools MUST be defined to check the connectivity,
trace the path and ensure fast detection of data plane failures on trace the path, and ensure fast detection of data plane failures on
P2MP LDP LSPs. P2MP LDP LSPs.
Further and precise requirements and mechanisms for P2MP MPLS OAM Further and precise requirements and mechanisms for P2MP MPLS
purpose are out of the scope of this document and are addressed in Operations, Administration, and Maintenance (OAM) purposes are out of
[RFC4687]. the scope of this document and are addressed in [RFC4687].
4.15. Graceful Restart and Fault Recovery 4.15. Graceful Restart and Fault Recovery
LDP Graceful Restart mechanisms [RFC3478] and Fault Recovery LDP Graceful Restart mechanisms [RFC3478] and Fault Recovery
mechanisms [RFC3479] SHOULD be enhanced to support P2MP LDP LSPs. mechanisms [RFC3479] SHOULD be enhanced to support P2MP LDP LSPs.
4.16. Robustness 4.16. Robustness
A solution MUST be designed to re-establish connectivity for P2MP and A solution MUST be designed to re-establish connectivity for P2MP and
MP2MP LSPs in the event of failures, provided there exists network MP2MP LSPs in the event of failures, provided there exists network
connectivity between ingress and egress nodes (i.e. designed without connectivity between ingress and egress nodes (i.e., designed without
introducing single points of failure). introducing single points of failure).
4.17. Scalability 4.17. Scalability
Scalability is a key requirement for the P2MP LDP mechanism. It MUST Scalability is a key requirement for the P2MP LDP mechanism. It MUST
be designed to scale well with an increase in the number of any of be designed to scale well with an increase in the number of any of
the following: the following:
o number of Leaf LSRs per P2MP LSP; o Number of Leaf LSRs per P2MP LSP;
o number of Downstream LSRs per Branch LSR; o Number of downstream LSRs per Branch LSR; and
o number of P2MP LSPs per LSR. o Number of P2MP LSPs per LSR.
In order to scale well with an increase in the number of leaves, it In order to scale well with an increase in the number of leaves, it
is RECOMMENDED that the size of a P2MP LSP state on a LSR, for one is RECOMMENDED that the size of a P2MP LSP state on an LSR, for one
particular LSP, depend only on the number of adjacent LSRs on the particular LSP, depend only on the number of adjacent LSRs on the
LSP. LSP.
4.17.1. Orders of Magnitude Expected in Operational Networks 4.17.1. Orders of Magnitude Expected in Operational Networks
Typical orders of magnitude that we expect should be supported are: Typical orders of magnitude that we expect should be supported are:
o tens of thousands of P2MP trees spread out across core network o Tens of thousands of P2MP trees spread out across core network
routers; routers; and
o hundreds, or a few thousands, of leaves per tree; o Hundreds, or a few thousands, of leaves per tree.
See also section 4.2 of [RFC4834]. See also Section 4.2 of [RFC4834].
4.18. Backward Compatibility 4.18. Backward Compatibility
In order to allow for a smooth migration, the P2MP LDP mechanism In order to allow for a smooth migration, the P2MP LDP mechanism
SHOULD offer as much backward compatibility as possible. In SHOULD offer as much backward compatibility as possible. In
particular, the solution SHOULD allow the setup of a P2MP LSP along particular, the solution SHOULD allow the setup of a P2MP LSP along
non-Branch Transit LSRs that do not support P2MP LDP extensions. non-Branch Transit LSRs that do not support P2MP LDP extensions.
Also, the P2MP LDP solution MUST co-exist with current LDP mechanisms Also, the P2MP LDP solution MUST coexist with current LDP mechanisms
and inherit its capability sets from [RFC5036]. The P2MP LDP and inherit its capability sets from [RFC5036]. The P2MP LDP
solution MUST NOT impede the operation of P2P/MP2P LSPs. A P2MP LDP solution MUST NOT impede the operation of P2P/MP2P LSPs. A P2MP LDP
solution MUST be designed in such a way that it allows P2P/MP2P and solution MUST be designed in such a way that it allows P2P/MP2P and
P2MP LSPs to be signalled on the same interface. P2MP LSPs to be signaled on the same interface.
5. Shared Trees 5. Shared Trees
For traffic delivery between a group of N LSRs that act as egress For traffic delivery between a group of N LSRs that act as egress
and/or egress nodes on different P2MP flows, it may be useful to and/or egress nodes on different P2MP flows, it may be useful to set
setup a shared tree connecting all these LSRs, instead of having N up a shared tree connecting all these LSRs instead of having N P2MP
P2MP LSPs. This would reduce the amount of control and forwarding LSPs. This would reduce the amount of control and forwarding state
state that has to be maintained on a given LSR. that has to be maintained on a given LSR.
There are actually two main options for supporting such shared trees: There are two main options for supporting such shared trees:
o This could rely on the applications protocols that use LDP LSPs. o Relying on the applications' protocols that use LDP LSPs. A
A shared tree could consist of the combination of a MP2P LDP LSP shared tree could consist of the combination of an MP2P LDP LSP
from Leafs LSRs to a given root node, with a P2MP LSP from this from Leaf LSRs to a given root node with a P2MP LSP from this root
root to Leaf LSRs. For instance with Multicast L3 VPN to Leaf LSRs. For instance, with Multicast L3 VPN applications,
applications, it would be possible to build a shared tree by it would be possible to build a shared tree by combining (see
combining (see [I-D.ietf-l3vpn-2547bis-mcast]): [MVPN]):
* a MP2P unicast LDP LSP, from each PE of the group to a * An MP2P unicast LDP LSP, from each PE router of the group to a
particular root PE acting as tree root, particular root PE router acting as tree root and
* with a P2MP LDP LSP from this root PE to each PE of the group. * A P2MP LDP LSP from this root PE router to each PE router of
the group.
o Or this could rely on a specific LDP mechanism allowing to setup o Relying on a specific LDP mechanism allowing the setup of
multipoint-to-multipoint MPLS LSPs (MP2MP LSPs). multipoint-to-multipoint MPLS LSPs (MP2MP LSPs).
The former approach (Combination of MP2P and P2MP LSPs at the The former approach (combination of MP2P and P2MP LSPs at the
application level) is out of the scope of this document while the application level) is out of the scope of this document while the
latter (MP2MP LSPs) belong to the scope of this document. latter (MP2MP LSPs) is within the scope of this document.
Requirements for the set up of MP2MP LSPs are listed below. Requirements for the setup of MP2MP LSPs are listed below.
5.1. Requirements for MP2MP LSPs 5.1. Requirements for MP2MP LSPs
A Multipoint-to-multipoint (MP2MP) LSP is an LSP connecting a group A multipoint-to-multipoint (MP2MP) LSP is an LSP connecting a group
of Leaf LSRs acting as Egress and/or Ingress LSRs. Traffic sent by of Leaf LSRs acting as Egress and/or Ingress LSRs. Traffic sent by
any Leaf LSR is received by all other Leaf LSRs of the group. any Leaf LSR is received by all other Leaf LSRs of the group.
Procedures for setting up MP2MP LSPs with LDP SHOULD be specified. Procedures for setting up MP2MP LSPs with LDP SHOULD be specified.
An implementation that support P2MP LDP LSPs MAY also support MP2MP An implementation that supports P2MP LDP LSPs MAY also support MP2MP
LDP LSP. LDP LSPs.
The MP2MP LDP procedures MUST NOT impede the operations of P2MP LSP. The MP2MP LDP procedures MUST NOT impede the operations of P2MP LSP.
Requirements for P2MP LSPs, set forth in Section 4, apply equally to Requirements for P2MP LSPs, set forth in Section 4, apply equally to
MP2MP LSPs. Particular attention should be given on the below MP2MP LSPs. Particular attention should be given to the requirements
requirements: below:
o The solution MUST support recovery upon link and transit node o The solution MUST support recovery upon link and transit node
failure and be designed to re-establish connectivity for MP2MP failure and be designed to re-establish connectivity for MP2MP
LSPs in the event of failures, provided there exists network LSPs in the event of failures, provided network connectivity
connectivity between ingress and egress nodes (i.e. designed exists between ingress and egress nodes (i.e., designed without
without introducing single points of failure); introducing single points of failure).
o The size of MP2MP state on a LSR, for one particular MP2MP LSP, o The size of MP2MP state on an LSR, for one particular MP2MP LSP,
SHOULD only depend on the number of adjacent LSRs on the LSP; SHOULD only depend on the number of adjacent LSRs on the LSP.
o Furthermore, the MP2MP LDP mechanism MUST avoid routing loops that o Furthermore, the MP2MP LDP mechanism MUST avoid routing loops that
may trigger exponential growth of traffic. Note that this may trigger exponential growth of traffic. Note that this
requirement is more challenging with MP2MP LSPs as a LSR may need requirement is more challenging with MP2MP LSPs as an LSR may need
to receive traffic for a given LSP on multiple interfaces. to receive traffic for a given LSP on multiple interfaces.
There are additional requirements specific to MP2MP LSPs: There are additional requirements specific to MP2MP LSPs:
o It is RECOMMENDED that a MP2MP MPLS LSP is built based on the o It is RECOMMENDED that an MP2MP MPLS LSP is built based on the
unicast route to a specific LSR called root LSR; unicast route to a specific LSR called root LSR.
o It is RECOMMENDED to define several root LSRs (e.g. a primary and o It is RECOMMENDED to define several root LSRs (e.g., a primary and
a backup) to ensure redundancy upon root LSR failure; a backup) to ensure redundancy upon root LSR failure.
o The receiver SHOULD NOT receive back a packet it has sent on the o The receiver SHOULD NOT receive back a packet it has sent on the
MP2MP LSP; MP2MP LSP.
o The solution SHOULD avoid that all traffic between any pair of o The solution SHOULD avoid that all traffic between any pair of
leaves is traversing a root LSR (similarly to PIM-Bidir trees) and leaves is traversing a root LSR (similarly to PIM-Bidir trees) and
SHOULD provide the operator with means to minimize the delay SHOULD provide the operator with means to minimize the delay
between two leaves; between two leaves.
o It MUST be possible to check connectivity of a MP2MP LSP in both o It MUST be possible to check connectivity of an MP2MP LSP in both
directions. directions.
6. Evaluation Criteria 6. Evaluation Criteria
6.1. Performance 6.1. Performance
The solution will be evaluated with respect to the following The solution will be evaluated with respect to the following
criteria: criteria:
(1) Efficiency of network resource usage; (1) Efficiency of network resource usage;
(2) Time to add or remove a Leaf LSR; (2) Time to add or remove a Leaf LSR;
(3) Time to repair a P2MP LSP in case of link or node failure; and
(3) Time to repair a P2MP LSP in case of link or node failure;
(4) Scalability (state size, number of messages, message size). (4) Scalability (state size, number of messages, message size).
Particularly the P2MP LDP mechanism SHOULD be designed with as key Particularly, the P2MP LDP mechanism SHOULD be designed with the key
objective to minimize the additional amount of state and additional objective of minimizing the additional amount of state and additional
processing required in the network. processing required in the network.
Also, the P2MP LDP mechanism SHOULD be designed so that convergence Also, the P2MP LDP mechanism SHOULD be designed so that convergence
times in case of link or node failure are minimized, in order to times in case of link or node failure are minimized, in order to
limit traffic disruption. limit traffic disruption.
6.2. Complexity and Risks 6.2. Complexity and Risks
The proposed solution SHOULD NOT introduce complexity to the current The proposed solution SHOULD NOT introduce complexity to the current
LDP operations to such a degree that it would affect the stability LDP operations to such a degree that it would affect the stability
and diminish the benefits of deploying such solution. and diminish the benefits of deploying such solution.
7. Security Considerations 7. Security Considerations
It is expected that addressing the requirements defined in this It is expected that addressing the requirements defined in this
document should not introduce any new security issue beyond those document should not introduce any new security issues beyond those
inherent to LDP, and that a P2MP LDP solution will rely on the inherent to LDP and that a P2MP LDP solution will rely on the
security mechanisms defined in [RFC5036] (e.g. TCP MD5 Signature). security mechanisms defined in [RFC5036] (e.g., TCP MD5 Signature).
An evaluation of the security features for MPLS networks may be found An evaluation of the security features for MPLS networks may be found
in [RFC5920], and where issues or further work is identified by that in [RFC5920], and where issues or further work is identified by that
document, new security features or procedures for the MPLS protocols document, new security features or procedures for the MPLS protocols
will need to be developed. will need to be developed.
8. IANA Considerations 8. Acknowledgments
This informational document makes no requests to IANA for action.
9. Acknowledgments
We would like to thank Christian Jacquenet, Hitoshi Fukuda, Ina We would like to thank Christian Jacquenet, Hitoshi Fukuda, Ina
Minei, Dean Cheng, and Benjamin Niven-Jenkins, for their highly Minei, Dean Cheng, and Benjamin Niven-Jenkins for their highly useful
useful comments and suggestions. We would also like to thank Adrian comments and suggestions. We would like to thank Adrian Farrel for
Farrel for reviewing this document before publication. reviewing this document before publication.
We would also like to thank authors of [RFC4461] from which some of
the text in this document has been inspired.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol We would also like to thank the authors of [RFC4461], which inspired
Label Switching Architecture", RFC 3031, January 2001. some of the text in this document.
[RFC3478] Leelanivas, M., Rekhter, Y., and R. Aggarwal, "Graceful 9. References
Restart Mechanism for Label Distribution Protocol",
RFC 3478, February 2003.
[RFC3479] Farrel, A., "Fault Tolerance for the Label Distribution 9.1. Normative References
Protocol (LDP)", RFC 3479, February 2003.
[RFC3815] Cucchiara, J., Sjostrand, H., and J. Luciani, "Definitions [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
of Managed Objects for the Multiprotocol Label Switching Requirement Levels", BCP 14, RFC 2119, March 1997.
(MPLS), Label Distribution Protocol (LDP)", RFC 3815,
June 2004.
[RFC4461] Yasukawa, S., "Signaling Requirements for Point-to- [RFC3031] Rosen, E., Viswanathan, A., and R. Callon,
Multipoint Traffic-Engineered MPLS Label Switched Paths "Multiprotocol Label Switching Architecture", RFC 3031,
(LSPs)", RFC 4461, April 2006. January 2001.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP [RFC3478] Leelanivas, M., Rekhter, Y., and R. Aggarwal, "Graceful
Specification", RFC 5036, October 2007. Restart Mechanism for Label Distribution Protocol",
RFC 3478, February 2003.
10.2. Informative References [RFC3479] Farrel, A., "Fault Tolerance for the Label Distribution
Protocol (LDP)", RFC 3479, February 2003.
[I-D.ietf-l2vpn-vpls-mcast] [RFC3815] Cucchiara, J., Sjostrand, H., and J. Luciani,
Aggarwal, R., Kamite, Y., Fang, L., and Y. Rekhter, "Definitions of Managed Objects for the Multiprotocol
"Multicast in VPLS", draft-ietf-l2vpn-vpls-mcast-08 (work Label Switching (MPLS), Label Distribution Protocol
in progress), October 2010. (LDP)", RFC 3815, June 2004.
[I-D.ietf-l3vpn-2547bis-mcast] [RFC4461] Yasukawa, S., "Signaling Requirements for Point-to-
Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y., Multipoint Traffic-Engineered MPLS Label Switched Paths
Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in (LSPs)", RFC 4461, April 2006.
MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-10 (work
in progress), January 2010.
[I-D.ietf-mpls-ldp-p2mp] [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Minei, I., Wijnands, I., Kompella, K., and B. Thomas, Specification", RFC 5036, October 2007.
"Label Distribution Protocol Extensions for Point-to-
Multipoint and Multipoint-to-Multipoint Label Switched
Paths", draft-ietf-mpls-ldp-p2mp-13 (work in progress),
April 2011.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 9.2. Informative References
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC4026] Andersson, L. and T. Madsen, "Provider Provisioned Virtual [MLDP] Minei, I., Wijnands, I., Kompella, K., and B. Thomas,
Private Network (VPN) Terminology", RFC 4026, March 2005. "Label Distribution Protocol Extensions for Point-to-
Multipoint and Multipoint-to-Multipoint Label Switched
Paths", Work in Progress, August 2011.
[RFC4687] Yasukawa, S., Farrel, A., King, D., and T. Nadeau, [MVPN] Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter,
"Operations and Management (OAM) Requirements for Point- Y., Rosen, E., Wijnands, I., and S. Yasukawa,
to-Multipoint MPLS Networks", RFC 4687, September 2006. "Multicast in MPLS/BGP IP VPNs", Work in Progress,
January 2010.
[RFC4834] Morin, T., Ed., "Requirements for Multicast in Layer 3 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
Provider-Provisioned Virtual Private Networks (PPVPNs)", V., and G. Swallow, "RSVP-TE: Extensions to RSVP for
RFC 4834, April 2007. LSP Tunnels", RFC 3209, December 2001.
[RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, [RFC4026] Andersson, L. and T. Madsen, "Provider Provisioned
"Extensions to Resource Reservation Protocol - Traffic Virtual Private Network (VPN) Terminology", RFC 4026,
Engineering (RSVP-TE) for Point-to-Multipoint TE Label March 2005.
Switched Paths (LSPs)", RFC 4875, May 2007.
[RFC5501] Kamite, Y., Wada, Y., Serbest, Y., Morin, T., and L. Fang, [RFC4687] Yasukawa, S., Farrel, A., King, D., and T. Nadeau,
"Requirements for Multicast Support in Virtual Private LAN "Operations and Management (OAM) Requirements for
Services", RFC 5501, March 2009. Point-to-Multipoint MPLS Networks", RFC 4687,
September 2006.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS [RFC4834] Morin, T., Ed., "Requirements for Multicast in Layer 3
Networks", RFC 5920, July 2010. Provider-Provisioned Virtual Private Networks
(PPVPNs)", RFC 4834, April 2007.
Authors' Addresses [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa,
"Extensions to Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007.
Jean-Louis Le Roux (editor) [RFC5501] Kamite, Y., Wada, Y., Serbest, Y., Morin, T., and L.
France Telecom - Orange Fang, "Requirements for Multicast Support in Virtual
Private LAN Services", RFC 5501, March 2009.
Email: jeanlouis.leroux@orange-ftgroup.com [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
Thomas Morin (editor) [VPLS-MCAST] Aggarwal, R., Kamite, Y., Fang, L., and Y. Rekhter,
France Telecom - Orange "Multicast in VPLS", Work in Progress, July 2011.
Email: thomas.morin@orange-ftgroup.com Contributing Authors
Vincent Parfait Vincent Parfait
France Telecom - Orange, Orange Business Services France Telecom - Orange, Orange Business Services
Email: vincent.parfait@orange-ftgroup.com EMail: vincent.parfait@orange-ftgroup.com
Luyuan Fang Luyuan Fang
Cisco Systems, Inc. Cisco Systems, Inc.
Email: lufang@cisco.com EMail: lufang@cisco.com
Lei Wang Lei Wang
Telenor Telenor
Email: lei.wang@telenor.com EMail: lei.wang@telenor.com
Yuji Kamite Yuji Kamite
NTT Communications Corporation NTT Communications Corporation
Email: y.kamite@ntt.com EMail: y.kamite@ntt.com
Shane Amante Shane Amante
Level 3 Communications, LLC Level 3 Communications, LLC
Email: shane@level3.net EMail: shane@level3.net
Authors' Addresses
Jean-Louis Le Roux (editor)
France Telecom - Orange
EMail: jeanlouis.leroux@orange-ftgroup.com
Thomas Morin (editor)
France Telecom - Orange
EMail: thomas.morin@orange-ftgroup.com
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