draft-ietf-mpls-mp-ldp-reqs-04.txt   draft-ietf-mpls-mp-ldp-reqs-05.txt 
Network Working Group J.-L. Le Roux (Editor) MPLS J. Le Roux, Ed.
Internet Draft France Telecom Internet-Draft T. Morin
Category: Informational Intended status: Informational V. Parfait
Expires: August 2008 Expires: May 30, 2011 France Telecom - Orange
L. Fang
March 2008 Cisco
L. Wang
Requirements for Point-To-Multipoint Extensions to Telenor
the Label Distribution Protocol Y. Kamite
NTT
draft-ietf-mpls-mp-ldp-reqs-04.txt S. Amante
Level3
Status of this Memo November 26, 2010
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress".
The list of current Internet-Drafts can be accessed at Requirements for Point-To-Multipoint Extensions to the Label
http://www.ietf.org/ietf/1id-abstracts.txt. Distribution Protocol
draft-ietf-mpls-mp-ldp-reqs-05
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Abstract Abstract
This document lists a set of functional requirements for Label This document lists a set of functional requirements for Label
Distribution Protocol (LDP) extensions for setting up point-to- Distribution Protocol (LDP) extensions for setting up point-to-
multipoint (P2MP) Label Switched Paths (LSP), in order to deliver multipoint (P2MP) Label Switched Paths (LSP), in order to deliver
point-to-multipoint applications over a Multi Protocol Label point-to-multipoint applications over a Multi Protocol Label
Switching (MPLS) infrastructure. It is intended that solutions that Switching (MPLS) infrastructure. It is intended that solutions that
specify LDP procedures for setting up P2MP LSP satisfy these specify LDP procedures for setting up P2MP LSP satisfy these
requirements. requirements.
Conventions used in this document Requirements Language
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].
Table of Contents Status of this Memo
1. Contributing Authors........................................3
2. Definitions.................................................3
2.1. Acronyms....................................................3
2.2. Terminology.................................................3
3. Introduction................................................5
4. Problem Statement and Requirements Overview.................6
4.1. Problem Statement...........................................6
4.2. Requirements overview.......................................6
5. Application scenario........................................7
6. Detailed Requirements.......................................8
6.1. P2MP LSPs...................................................8
6.2. P2MP LSP FEC................................................8
6.3. P2MP LDP routing............................................9
6.4. Setting up, tearing down and modifying P2MP LSPs............9
6.5. Label Advertisement.........................................9
6.6. Data Duplication............................................9
6.7. Detecting and Avoiding Loops...............................10
6.8. P2MP LSP Re-routing........................................10
6.8.1. Rerouting upon Network Failure.............................10
6.8.2. Rerouting on a Better Path.................................10
6.8.3. Rerouting upon Planned Maintenance.........................11
6.9. Support for LAN interfaces.................................11
6.10. Support for encapsulation in P2P and P2MP TE tunnels.......11
6.11. Label spaces...............................................11
6.12. IPv4/IPv6 support..........................................11
6.13. Multi-Area/AS LSPs.........................................12
6.14. OAM........................................................12
6.15. Graceful Restart and Fault Recovery........................12
6.16. Robustness.................................................12
6.17. Scalability................................................12
6.17.1. Orders of magnitude expected in operational networks......13
6.18. Backward Compatibility.....................................13
7. Shared Trees...............................................13
7.1. Requirements for MP2MP LSPs................................14
8. Evaluation criteria........................................14
8.1. Performances...............................................14
8.2. Complexity and Risks.......................................15
9. Security Considerations....................................15
10. IANA Considerations........................................15
11. Acknowledgments............................................15
12. References.................................................15
12.1. Normative references.......................................15
12.2. Informative references.....................................16
13. Editor's Address...........................................16
14. Contributors' Addresses....................................17
15. Intellectual Property Statement............................18
1. Contributing Authors
The co-authors listed below contributed to the text and content of
this document.
Shane Amante, Level 3 Communications, LLC.
Luyuan Fang, Cisco Systems.
Yuji Kamite, NTT Communications Corporation.
Jean-Louis Le Roux, France Telecom.
Thomas Morin, France Telecom.
Vincent Parfait, Orange Business Services.
Lei Wang, Telenor.
2. Definitions This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
2.1. Acronyms Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
P2P: Point-To-Point Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
P2MP: Point-To-MultiPoint The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
MP2MP: MultiPoint-To-Multipoint The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
PE: Provider Edge router This Internet-Draft will expire on May 30, 2011.
P: Provider router Copyright Notice
IGP: Interior Gateway Protocol Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
AS: Autonomous System This document is subject to BCP 78 and the IETF Trust's Legal
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described in the BSD License.
2.2. Terminology Table of Contents
The reader is assumed to be familiar with the terminology in 1. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4
[RFC3031], [RFC5036], and [RFC4026]. 1.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Problem Statement and Requirements Overview . . . . . . . . . 6
3.1. Problem Statement . . . . . . . . . . . . . . . . . . . . 6
3.2. Requirements overview . . . . . . . . . . . . . . . . . . 7
4. Application scenario . . . . . . . . . . . . . . . . . . . . . 7
5. Detailed Requirements . . . . . . . . . . . . . . . . . . . . 9
5.1. P2MP LSPs . . . . . . . . . . . . . . . . . . . . . . . . 9
5.2. P2MP LSP FEC . . . . . . . . . . . . . . . . . . . . . . . 9
5.3. P2MP LDP routing . . . . . . . . . . . . . . . . . . . . . 9
5.4. Setting up, tearing down and modifying P2MP LSPs . . . . . 9
5.5. Label Advertisement . . . . . . . . . . . . . . . . . . . 10
5.6. Data Duplication . . . . . . . . . . . . . . . . . . . . . 10
5.7. Detecting and Avoiding Loops . . . . . . . . . . . . . . . 10
5.8. P2MP LSP Re-routing . . . . . . . . . . . . . . . . . . . 11
5.9. Support for LAN interfaces . . . . . . . . . . . . . . . . 12
5.10. Support for encapsulation in P2P and P2MP TE tunnels . . . 12
5.11. Label spaces . . . . . . . . . . . . . . . . . . . . . . . 12
5.12. IPv4/IPv6 support . . . . . . . . . . . . . . . . . . . . 12
5.13. Multi-Area/AS LSPs . . . . . . . . . . . . . . . . . . . . 12
5.14. OAM . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.15. Graceful Restart and Fault Recovery . . . . . . . . . . . 13
5.16. Robustness . . . . . . . . . . . . . . . . . . . . . . . . 13
5.17. Scalability . . . . . . . . . . . . . . . . . . . . . . . 13
5.18. Backward Compatibility . . . . . . . . . . . . . . . . . . 14
6. Shared Trees . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1. Requirements for MP2MP LSPs . . . . . . . . . . . . . . . 15
7. Evaluation criteria . . . . . . . . . . . . . . . . . . . . . 16
7.1. Performances . . . . . . . . . . . . . . . . . . . . . . . 16
7.2. Complexity and Risks . . . . . . . . . . . . . . . . . . . 16
8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
11.1. Normative References . . . . . . . . . . . . . . . . . . . 17
11.2. Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
Ingress LSR: 1. Definitions
Router acting as a sender of an LSP 1.1. Acronyms
Egress LSR: P2P: Point-To-Point
Router acting as a receiver of an LSP P2MP: Point-To-MultiPoint
P2P LSP: MP2MP: MultiPoint-To-Multipoint
A LSP that has one unique Ingress LSR and one unique PE: Provider Edge router
Egress LSR
MP2P LSP: P: Provider router
A LSP that has one or more Ingress LSRs and one unique IGP: Interior Gateway Protocol
Egress LSR
P2MP LSP: AS: Autonomous System
A LSP that has one unique Ingress LSR and one or more 1.2. Terminology
Egress LSRs
MP2MP LSP: The reader is assumed to be familiar with the terminology in
[RFC3031], [RFC5036], and [RFC4026].
A LSP that as one or more Leaf LSRs acting indifferently as Ingress LSR:
Ingress or Egress LSR Router acting as a sender of an LSP
Leaf LSR: Egress LSR:
Router acting as a receiver of an LSP
Egress LSR of a P2MP LSP or Ingress/Egress LSR of a MP2MP LSP P2P LSP:
A LSP that has one unique Ingress LSR and one unique Egress LSR
Transit LSR: MP2P LSP:
A LSP that has one or more Ingress LSRs and one unique Egress LSR
A LSR of a P2MP or MP2MP LSP that has one or more Downstream P2MP LSP:
LSRs A LSP that has one unique Ingress LSR and one or more Egress LSRs
Branch LSR: MP2MP LSP:
A LSP that as one or more Leaf LSRs acting indifferently as
Ingress or Egress LSR
A LSR of a P2MP or MP2MP LSP that has more than one Leaf LSR:
downstream LSR Egress LSR of a P2MP LSP or Ingress/Egress LSR of a MP2MP LSP
Bud LSR: Transit LSR:
A LSR of a P2MP or MP2MP LSP that has one or more Downstream LSRs
A LSR of a P2MP or MP2MP LSP that is an egress but also Branch LSR:
has one or more directly connected downstream LSR(s) A LSR of a P2MP or MP2MP LSP that has more than one downstream LSR
P2MP tree: Bud LSR:
A LSR of a P2MP or MP2MP LSP that is an egress but also has one or
more directly connected downstream LSR(s)
The ordered set of LSRs and links that comprise the path of a P2MP tree:
P2MP LSP from its ingress LSR to all of its egress LSRs. 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.
3. Introduction 2. Introduction
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 [L2VPN-MCAST-REQ]. [RFC4834] and [RFC5501].
This requires mechanisms for setting up point-to-multipoint LSPs This requires mechanisms for setting up point-to-multipoint LSPs
(P2MP LSP), i.e. LSPs with one Ingress LSR, a set of Egress LSRs, and (P2MP LSP), i.e. LSPs with one Ingress LSR, a set of Egress LSRs,
with MPLS traffic replication at some Branch LSRs. and with MPLS traffic replication at some Branch LSRs.
RSVP-TE extensions for setting up Point-To-Multipoint Traffic RSVP-TE extensions for setting up Point-To-Multipoint Traffic
Engineered LSPs (P2MP TE LSPs), have been defined in [RFC4875]. Engineered LSPs (P2MP TE LSPs), have been defined in [RFC4875]. They
They meet requirements expressed in [RFC4461]. This approach is meet requirements expressed in [RFC4461]. This approach is useful,
useful, in network environments where P2MP Traffic Engineering in network environments where P2MP Traffic Engineering capabilities
capabilities are needed (Optimization, QoS, Fast recovery). are needed (Optimization, QoS, Fast recovery).
However for operators who want to support point-to-multipoint traffic However for operators who want to support point-to-multipoint traffic
delivery on an MPLS backbone, without Traffic Engineering needs, and delivery on an MPLS backbone, without Traffic Engineering needs, and
have already deployed LDP for P2P traffic, an interesting and useful have already deployed LDP for P2P traffic, an interesting and useful
approach would be to rely on LDP extensions in order to setup point- approach would be to rely on LDP extensions in order to setup point-
to-multipoint (P2MP) LSPs. This would bring consistency with P2P MPLS to-multipoint (P2MP) LSPs. This would bring consistency with P2P
applications and would ease the delivery of point-to-multipoint MPLS applications and would ease the delivery of point-to-multipoint
services in an MPLS backbone. services in an MPLS backbone.
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 a LDP-enabled MPLS infrastructure.
These requirements should be used as guidelines when specifying LDP These requirements should be used as guidelines when specifying LDP
extensions. It is intended that solutions that specify LDP procedures extensions. It is intended that solutions that specify LDP
for P2MP LSP setup, satisfy these requirements. procedures for P2MP LSP setup, satisfy these requirements.
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 solution
specific requirements related to LDP extensions in order to set up specific requirements related to LDP extensions in order to set up
P2MP LSPs. 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, such as for instance PIM extensions, but these are out of the
scope of this document. The objective is not to compare these scope of this document. The objective is not to compare these
mechanisms but rather to focus on the requirements for an LDP mechanisms but rather to focus on the requirements for an LDP
extension approach. extension approach.
The document is structured as follows: The document is structured as follows:
- Section 4 points out the problem statement;
- Section 5 illustrates an application scenario;
- Section 6 addresses detailed requirements for P2MP LSPs;
- Section 7 finally discusses requirements for
MultiPoint-to-MultiPoint (MP2MP) LSPs.
4. Problem Statement and Requirements Overview o Section 3 points out the problem statement;
4.1. Problem Statement o Section 4 illustrates an application scenario;
o Section 5 addresses detailed requirements for P2MP LSPs;
o Section Section 6 finally discusses requirements for shared trees
and MultiPoint-to-MultiPoint (MP2MP) LSPs.
3. Problem Statement and Requirements Overview
3.1. Problem Statement
LDP [RFC5036] has been deployed for setting up P2P and MP2P MPLS LSPs LDP [RFC5036] has been deployed for setting up P2P and MP2P MPLS LSPs
as PE-to-PE tunnels so as to carry point-to-point traffic essentially as PE-to-PE tunnels so as to carry point-to-point traffic essentially
in Layer 3 and Layer 2 VPN networks. There are emerging requirements in Layer 3 and Layer 2 VPN networks. There are emerging requirements
for supporting multicast traffic delivery within these VPN for supporting multicast traffic delivery within these VPN
infrastructures ([RFC4834] and [L2VPN-MCAST-REQ]). For various infrastructures ([RFC4834] and [RFC5501]). For various reasons,
reasons, including consistency with P2P applications, and taking full including consistency with P2P applications, and taking full
advantages of MPLS network infrastructure, it would be highly advantages of MPLS network infrastructure, it would be highly
desirable to use MPLS LSPs for the delivery of multicast traffic. desirable to use MPLS LSPs for the delivery of multicast traffic.
This could be implemented by setting up a group of P2P or MP2P LSPs, This could be implemented by setting up a group of P2P or MP2P LSPs,
but such an approach may be sub-optimal since it would result in data but such an approach may be sub-optimal since it would result in data
replication at the ingress LSR, and bandwidth inefficiency (duplicate replication at the ingress LSR, and bandwidth inefficiency (duplicate
data traffic within the network). Hence new mechanisms are required data traffic within the network). Hence new mechanisms are required
that would allow traffic from an Ingress LSR to be efficiently that would allow traffic from an Ingress LSR to be efficiently
delivered to a number of Egress LSRs in an MPLS backbone, avoiding delivered to a number of Egress LSRs in an MPLS backbone, avoiding
duplicate copies of a packet on a given link. duplicate copies of a packet on a given link.
Such efficient traffic delivery requires setting up P2MP LSPs. A P2MP Such efficient traffic delivery requires setting up P2MP LSPs. A
LSP is an LSP starting at an Ingress LSR, and ending on a set of one P2MP LSP is an LSP starting at an Ingress LSR, and ending on a set of
or more Egress LSRs. Traffic sent by the Ingress LSR is replicated on one or more Egress LSRs. Traffic sent by the Ingress LSR is
one or more Branch LSRs down to Egress LSRs. replicated on one or more Branch LSRs down to Egress LSRs.
RSVP-TE extensions for setting up P2MP TE LSPs, which meet RSVP-TE extensions for setting up P2MP TE LSPs, which meet
requirements expressed in [RFC4461], have been defined in [RFC4875]. requirements expressed in [RFC4461], have been defined in [RFC4875].
This approach is useful, in network environments where Traffic This approach is useful, in network environments where Traffic
Engineering capabilities are required. However, for operators that Engineering capabilities are required. However, for operators that
deployed LDP for setting up PE-to-PE unicast MPLS LSPs, and without deployed LDP for setting up PE-to-PE unicast MPLS LSPs, and without
the need for traffic engineering, an interesting approach would be the need for traffic engineering, an interesting approach would be
using LDP extensions for setting up P2MP LSPs. using LDP extensions for setting up P2MP LSPs.
The following gives a set of guidelines that a specification of LDP The following gives a set of guidelines that a specification of LDP
extensions for setting up P2MP LSPs should follow. extensions for setting up P2MP LSPs should follow.
4.2. Requirements overview 3.2. 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 co-exist 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 co-
exist with P2P and P2MP RSVP-TE mechanisms [RFC3209], [RFC4875]. It exist 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 a
LSR. LSR.
5. Application scenario 4. 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 [2547-MCAST] for following for instance the architecture defined in
BGP/MPLS VPNs, or the one defined in [VPLS-MCAST]. [I-D.ietf-l3vpn-2547bis-mcast] for BGP/MPLS VPNs, or the one defined
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 are setup 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.
And in this example a set of P2MP LDP LSPs are setup between PE And in this example a set of P2MP LDP LSPs are setup between PE
routers acting as Ingress LSRs and PE routers acting as Egress LSRs, routers acting as Ingress LSRs and PE routers acting as Egress LSRs,
so as to support multicast VPN traffic delivery within the MPLS so as to 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 setup 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 are
non-branch transit LSRs, they forward MPLS traffic sent by P1 to PE3 non-branch transit LSRs, they forward MPLS traffic sent by P1 to PE3
and PE4 respectively. 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 respectively (see figure 2 below). PE6 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. The above example is provided for the sake of illustration. Note
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.
6. Detailed Requirements 5. Detailed Requirements
6.1. P2MP LSPs 5.1. P2MP LSPs
The P2MP LDP mechanism MUST support setting up P2MP LSPs. The P2MP LDP mechanism MUST support setting up P2MP LSPs. Data plane
Data plane aspects related to P2MP LSPs are those already defined in aspects related to P2MP LSPs are those already defined in [RFC4461].
[RFC4461]. That is, a P2MP LSP has one Ingress LSR and one or That is, a P2MP LSP has one Ingress LSR and one or more Egress LSRs.
more Egress LSRs. Traffic sent by the Ingress LSR is received by all Traffic sent by the Ingress LSR is received by all Egress LSRs. The
Egress LSRs. The specific aspects related to P2MP LSPs is the action specific aspects related to P2MP LSPs is the action required at a
required at a Branch LSR, where data replication occurs. Branch LSR, where data replication occurs. Incoming labelled data is
Incoming labelled data is appropriately replicated to several appropriately replicated to several outgoing interfaces which may use
outgoing interfaces which may use different labels. Only one copy of different labels. Only one copy of a packet MUST be sent on a given
a packet MUST be sent on a given link of a P2MP LSP. link of a P2MP LSP.
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 within the whole LDP domain, whatever the number of leaves, which may
may vary dynamically. This identifier will be used so as to vary dynamically. This identifier will be used so as to add/remove
add/remove leaves to/from the P2MP tree. leaves to/from the P2MP tree.
6.2. P2MP LSP FEC 5.2. 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 FEC in this P2MP extension. All packets which belong to a
particular P2MP FEC and which travel from a particular node MUST use particular P2MP FEC and which travel from a particular node MUST use
the same P2MP LSP. the same P2MP LSP.
As such, a new LDP FEC that is suitable for P2MP forwarding MUST be As such, a new LDP FEC that is suitable for P2MP forwarding MUST be
specified. specified.
6.3. P2MP LDP routing 5.3. 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 (RIB).
It is RECOMMENDED that the P2MP LSP routing rely upon a shortest path It is RECOMMENDED that the P2MP LSP routing rely upon a shortest path
to the Ingress LSR so as to setup an MPLS shortest path tree. to the Ingress LSR so as to setup an MPLS shortest path tree.
6.4. Setting up, tearing down and modifying P2MP LSPs 5.4. 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 amount of P2MP LSPs within a single
network and a large amount of leaf LSRs for a single P2MP LSP (see network and a large amount of leaf LSRs for a single P2MP LSP (see
also section 5.17 for scalability considerations and figures). also section 5.17 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 LSPs 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. operations be leaf-initiated. These operations MUST not impact the
These operations MUST not impact the data transfer (packet loss, data transfer (packet loss, duplication, delay) towards other leaves.
duplication, delay) towards other leaves. It is RECOMMENDED that It is RECOMMENDED that these operations do not cause any additional
these operations do not cause any additional processing except on the processing except on the path from the added/removed Leaf LSR to the
path from the added/removed Leaf LSR to the Branch LSR. Branch LSR.
6.5. Label Advertisement 5.5. Label Advertisement
The P2MP LDP mechanism MUST support downstream unsolicited label The P2MP LDP mechanism MUST support downstream unsolicited label
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.
6.6. Data Duplication 5.6. 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 as much as possible be avoided, and limited to (hopefully
rare) transitory conditions. rare) 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 6.8). rerouting is being performed (See also section 6.8).
6.7. Detecting and Avoiding Loops 5.7. 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, that may trigger unexpected non-localized exponential
growth of traffic. growth of traffic.
6.8. P2MP LSP Re-routing 5.8. P2MP LSP Re-routing
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:
- Network failure (link or node);
- A better path exists (e.g. new link, metric change); o Network failure (link or node);
- Planned maintenance.
o A better path exists (e.g. new link, metric change);
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 also implies the underlying routing of the following requirements also implies the underlying routing
protocols (IGP, etc.). protocols (IGP, etc.).
6.8.1. Rerouting upon Network Failure 5.8.1. 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 rebuild which may be caused by the instability of a specific link/
link/node in the network. This will rely on IGP dampening but may be node in the network. This will rely on IGP dampening but may be
completed by specific dampening at the LDP level. completed by specific dampening at the LDP level.
6.8.2. Rerouting on a Better Path 5.8.2. 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.
6.8.3. Rerouting upon Planned Maintenance 5.8.3. 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. deactivated for maintenance purposes. Traffic disruption and data
Traffic disruption and data duplication SHOULD be minimized as much duplication SHOULD be minimized as much as possible during such
as possible during such planned maintenance. planned maintenance. P2MP LSP rerouting upon planned maintenance MAY
P2MP LSP rerouting upon planned maintenance MAY rely on a make before rely on a make before break procedure.
break procedure.
6.9. Support for LAN interfaces 5.9. Support for LAN interfaces
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 Ethernet LAN interface and reach a single copy of the data onto an Ethernet LAN interface and reach
multiple adjacent downstream nodes. This requires that the same label multiple adjacent downstream nodes. This requires that the same
be negotiated with all downstream LSRs for the LSP. label be negotiated with all downstream LSRs for the LSP.
When there are several candidate upstream LSRs on a LAN interface, When there are several candidate upstream LSRs on a LAN interface,
the P2MP LDP mechanism SHOULD provide a way for all downstream LSRs the P2MP LDP mechanism SHOULD provide a way for all downstream LSRs
of a given P2MP LSP to select the same upstream LSR, so as to avoid of a given P2MP LSP to select the same upstream LSR, so as to avoid
traffic replication. In addition, the P2MP LDP mechanism SHOULD allow traffic replication. In addition, the P2MP LDP mechanism SHOULD
for an efficient balancing of a set of P2MP LSPs among a set of allow for an efficient balancing of a set of P2MP LSPs among a set of
candidate upstream LSRs on a LAN interface. candidate upstream LSRs on a LAN interface.
6.10. Support for encapsulation in P2P and P2MP TE tunnels 5.10. Support for encapsulation in P2P and P2MP TE tunnels
The P2MP LDP mechanism MUST support nesting P2MP LSPs into P2P and The P2MP LDP mechanism MUST support nesting P2MP LSPs into P2P and
P2MP TE tunnels. P2MP TE tunnels.
The P2MP LDP mechanism MUST provide a way for a Branch LSR of a P2MP The P2MP LDP mechanism MUST provide a way for a Branch LSR of a P2MP
LSP, which is also a Head End LSR of a P2MP TE tunnel, to send a LSP, which is also a Head End LSR of a P2MP TE tunnel, to send a
single copy of the data onto the tunnel and reach all downstream LSRs single copy of the data onto the tunnel and reach all downstream LSRs
on the P2MP LSP, which are also Egress LSRs of the tunnel. As with on the P2MP LSP, which are also Egress LSRs of the tunnel. As with
LAN interfaces, this requires that the same label be negotiated with LAN interfaces, this requires that the same label be negotiated with
all downstream LSRs of the P2MP LDP LSP. all downstream LSRs of the P2MP LDP LSP.
6.11. Label spaces 5.11. Label spaces
Labels for P2MP LSPs and P2P/MP2P LSPs MAY be assigned from shared or Labels for P2MP LSPs and P2P/MP2P LSPs MAY be assigned from shared or
dedicated label spaces. dedicated label spaces.
Note that dedicated label spaces will require the establishment of Note that dedicated label spaces will require the establishment of
separate P2P and P2MP LDP sessions. separate P2P and P2MP LDP sessions.
6.12. IPv4/IPv6 support 5.12. 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.
6.13. Multi-Area/AS LSPs 5.13. 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 inter- The P2MP LDP mechanism MUST also support the establishment of
AS P2MP LSPs, i.e. LSPs whose leaves do not all reside in the same AS inter-AS P2MP LSPs, i.e. LSPs whose leaves do not all reside in the
as the Ingress LSR. This SHOULD be possible without requiring the same AS as the Ingress LSR. This SHOULD be possible without
advertisement of Ingress LSRs' addresses across ASes. requiring the advertisement of Ingress LSRs' addresses across ASes.
6.14. OAM 5.14. 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 OAM
purpose are out of the scope of this document and are addressed in purpose are out of the scope of this document and are addressed in
[RFC4687]. [RFC4687].
6.15. Graceful Restart and Fault Recovery 5.15. 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.
6.16. Robustness 5.16. Robustness
A solution MUST avoid single points of failures provided there is A solution MUST avoid single points of failures provided there is
enough network connectivity. enough network connectivity.
6.17. Scalability 5.17. Scalability
Scalability is a key requirement for the P2MP LDP mechanism. Scalability is a key requirement for the P2MP LDP mechanism. It MUST
It MUST be designed to scale well with an increase in the number of be designed to scale well with an increase in the number of any of
any of the following: the following:
- number of Leaf LSRs per P2MP LSP;
- number of Downstream LSRs per Branch LSR; o number of Leaf LSRs per P2MP LSP;
- number of P2MP LSPs per LSR.
o number of Downstream LSRs per Branch 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 a 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.
6.17.1. Orders of magnitude expected in operational networks 5.17.1. 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:
- 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;
- 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].
6.18. Backward Compatibility 5.18. 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 co-exist with current LDP mechanisms
and inherit its capability sets from [RFC5036]. The P2MP LDP solution and inherit its capability sets from [RFC5036]. The P2MP LDP
MUST not impede the operation of P2P/MP2P LSPs. A P2MP LDP solution solution MUST not impede the operation of P2P/MP2P LSPs. A P2MP LDP
MUST be designed in such a way that it allows P2P/MP2P and P2MP LSPs solution MUST be designed in such a way that it allows P2P/MP2P and
to be signalled on the same interface. P2MP LSPs to be signalled on the same interface.
7. Shared Trees 6. Shared Trees
For traffic delivery between a group of N Leaf LSRs which are acting For traffic delivery between a group of N Leaf LSRs which are acting
indifferently as Ingress or Egress LSRs, it may be useful to indifferently as Ingress or Egress LSRs, it may be useful to setup a
setup a shared tree connecting all these LSRs, instead of having N shared tree connecting all these LSRs, instead of having N P2MP LSPs.
P2MP LSPs. This would reduce the amount of control and forwarding This would reduce the amount of control and forwarding state that has
state that has to be maintained on a given LSR. to be maintained on a given LSR.
There are actually two main options for supporting such shared trees: There are actually two main options for supporting such shared trees:
- This could rely on the applications protocols that use LDP o This could rely on the applications protocols that use LDP LSPs.
LSPs. A shared tree could consist of the combination of a A shared tree could consist of the combination of a MP2P LDP LSP
MP2P LDP LSP from Leafs LSRs to a given root node, with a P2MP from Leafs LSRs to a given root node, with a P2MP LSP from this
LSP from this root to Leaf LSRs. For instance with root to Leaf LSRs. For instance with Multicast L3 VPN
Multicast L3 VPN applications, it would be possible to build a applications, it would be possible to build a shared tree by
shared tree by combining (see [2547-MCAST]): combining (see [I-D.ietf-l3vpn-2547bis-mcast]):
- a MP2P unicast LDP LSP, from each PE of the group to a
particular root PE acting as tree root,
- with a P2MP LDP LSP from this root PE to each PE of the
group.
- Or this could rely on a specific LDP mechanism allowing to * a MP2P unicast LDP LSP, from each PE of the group to a
setup multipoint-to-multipoint MPLS LSPs (MP2MP LSPs). particular root PE acting as tree root,
* with a P2MP LDP LSP from this root PE to each PE of the group.
o Or this could rely on a specific LDP mechanism allowing to setup
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) belong to the scope of this document.
Requirements for the set up of MP2MP LSPs are listed below. Requirements for the set up of MP2MP LSPs are listed below.
7.1. Requirements for MP2MP LSPs 6.1. Requirements for MP2MP LSPs
A MP2MP LSP is a LSP connecting a group of Leaf LSRs acting A MP2MP LSP is a LSP connecting a group of Leaf LSRs acting
indifferently as Ingress or Egress LSRs. Traffic sent by any Leaf LSR indifferently as Ingress or Egress LSRs. Traffic sent by any Leaf
is received by all other Leaf LSRs of the group. 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 support P2MP LDP LSPs MAY also support MP2MP
LDP LSP. LDP LSP.
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 6, apply equally to Requirements for P2MP LSPs, set forth in section 6, apply equally to
MP2MP LSPs. Particular attention should be given on the below MP2MP LSPs. Particular attention should be given on the below
requirements: requirements:
- The solution MUST support recovery upon link and transit node o The solution MUST support recovery upon link and transit node
failure and there MUST NOT be any single point of failure (provided failure and there MUST NOT be any single point of failure
network connectivity is redundant); (provided network connectivity is redundant);
- The size of MP2MP state on a LSR, for one particular MP2MP LSP,
SHOULD only depend on the number of adjacent LSRs on the LSP;
- Furthermore, the MP2MP LDP mechanism MUST avoid routing loops that
may trigger exponential growth of traffic. Note that this
requirement is more challenging with MP2MP LSPs as a LSR can
receive traffic for a given LSP on multiple interfaces.
There are additional requirements specific to MP2MP LSPs: o The size of MP2MP state on a LSR, for one particular MP2MP LSP,
SHOULD only depend on the number of adjacent LSRs on the LSP;
- It is RECOMMENDED that a MP2MP MPLS LSP follow shortest paths to a o Furthermore, the MP2MP LDP mechanism MUST avoid routing loops that
specific LSR called root LSR; may trigger exponential growth of traffic. Note that this
- It is RECOMMENDED to define several root LSRs (e.g. a primary and requirement is more challenging with MP2MP LSPs as a LSR can
receive traffic for a given LSP on multiple interfaces.
There are additional requirements specific to MP2MP LSPs:
o It is RECOMMENDED that a MP2MP MPLS LSP follow shortest paths to a
specific LSR called root LSR;
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;
- The receiver SHOULD not receive back a packet it has sent on the
MP2MP LSP; o The receiver SHOULD not receive back a packet it has sent on the
- The solution SHOULD avoid that all traffic between any pair of MP2MP LSP;
leaves is traversing a root LSR, and SHOULD as much as possible
minimize the distance between two leaves (similarly to PIM-Bidir o The solution SHOULD avoid that all traffic between any pair of
trees); leaves is traversing a root LSR, and SHOULD as much as possible
- It MUST be possible to check connectivity of a MP2MP LSP in both minimize the distance between two leaves (similarly to PIM-Bidir
trees);
o It MUST be possible to check connectivity of a MP2MP LSP in both
directions. directions.
8. Evaluation criteria 7. Evaluation criteria
8.1. Performances 7.1. Performances
The solution will be evaluated with respect to the following The solution will be evaluated with respect to the following
criteria: criteria:
(1) Time to add or remove a Leaf LSR; (1) Time to add or remove a Leaf LSR;
(2) Time to repair a P2MP LSP in case of link or node
failure; (2) Time to repair a P2MP LSP in case of link or node failure;
(3) Scalability (state size, number of messages, message size).
(3) 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 as key
objective to minimize the additional amount of state and additional objective to minimize 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.
8.2. Complexity and Risks 7.2. 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.
9. Security Considerations 8. Security Considerations
This document does not introduce any new security issue beyond those This document does not introduce any new security issue beyond those
inherent to LDP, and a P2MP LDP solution will rely on the security inherent to LDP, and a P2MP LDP solution will rely on the security
mechanisms defined in [RFC5036] (e.g. TCP MD5 Signature). 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 [MPLS-SEC], 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.
10. IANA Considerations 9. IANA Considerations
This informational document makes no requests to IANA for action. This informational document makes no requests to IANA for action.
11. Acknowledgments 10. Acknowledgments
We would like to thank Christian Jacquenet (France Telecom), We would like to thank Christian Jacquenet (France Telecom), Hitoshi
Hitoshi Fukuda (NTT Communications), Ina Minei (Juniper), Dean Fukuda (NTT), Ina Minei (Juniper), Dean Cheng (Cisco), and Benjamin
Cheng (Cisco Systems), and Benjamin Niven-Jenkins (British Telecom), Niven-Jenkins (BT), for their highly useful comments and suggestions.
for their highly useful comments and suggestions.
We would also like to thank authors of [RFC4461] from which some text We would also like to thank authors of [RFC4461] from which some text
of this document has been inspired. of this document has been inspired.
12. References 11. References
12.1. Normative references 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5036] L. Andersson, I. Minei, B. Thomas, "LDP Specification", RFC [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
5036, September 2006. Label Switching Architecture", RFC 3031, January 2001.
[RFC3815] J. Cuchiarra et al. "Definitions of Managed Objects for the [RFC3478] Leelanivas, M., Rekhter, Y., and R. Aggarwal, "Graceful
Multiprotocol Label Switching (MPLS), Label Distribution Protocol Restart Mechanism for Label Distribution Protocol",
(LDP)", RFC 3815, June 2004. RFC 3478, February 2003.
[RFC3478] M. Leelanivas, Y. Rekhter, R. Aggarwal, "Graceful Restart [RFC3479] Farrel, A., "Fault Tolerance for the Label Distribution
Mechanism for Label Distribution Protocol" RFC 3478, February 2003. Protocol (LDP)", RFC 3479, February 2003.
[RFC3479] A. Farrel, "Fault Tolerance for the Label Distribution [RFC3815] Cucchiara, J., Sjostrand, H., and J. Luciani, "Definitions
Protocol (LDP)", RFC 3479, February 2003. of Managed Objects for the Multiprotocol Label Switching
(MPLS), Label Distribution Protocol (LDP)", RFC 3815,
June 2004.
12.2. Informative references [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC4834] T. Morin, Ed., "Requirements for Multicast in L3 11.2. Informative References
Provider-Provisioned VPNs", RFC 4834, April 2007.
[L2VPN-MCAST-REQ] Y. Kamite et al. "Requirements for Multicast [I-D.ietf-l2vpn-vpls-mcast]
Support in Virtual Private LAN Services", draft-ietf-l2vpn-vpls- Aggarwal, R., Kamite, Y., Fang, L., and Y. Rekhter,
mcast-reqts, work in progress. "Multicast in VPLS", draft-ietf-l2vpn-vpls-mcast-08 (work
in progress), October 2010.
[2547-MCAST] E. Rosen, R. Aggarwal, et. al., "Multicast in MPLS/BGP [I-D.ietf-l3vpn-2547bis-mcast]
IP VPNs", draft-ietf-l3vpn-2547bis-mcast, work in progress. Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y.,
Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in
MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-10 (work
in progress), January 2010.
[VPLS-MCAST] R.Aggarwal, Y Kamite, L Fang, "VPLS Multicast" draft- [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
ietf-l2vpn-vpls-mcast, work in progress. and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC4687] S. Yasukawa, A. Farrel, D. King, T. Nadeau, "OAM [RFC4026] Andersson, L. and T. Madsen, "Provider Provisioned Virtual
Requirements for Point-To-Multipoint MPLS Networks", RFC 4687, Private Network (VPN) Terminology", RFC 4026, March 2005.
September 2006.
[RFC4461] S. Yasukawa, et. al., "Requirements for Point-to-Multipoint [RFC4461] Yasukawa, S., "Signaling Requirements for Point-to-
capability extension to MPLS", RFC 4461, April 2006. Multipoint Traffic-Engineered MPLS Label Switched Paths
(LSPs)", RFC 4461, April 2006.
[RFC4875] R. Aggarwal, D. Papadimitriou, S. Yasukawa, et. al., [RFC4687] Yasukawa, S., Farrel, A., King, D., and T. Nadeau,
"Extensions to RSVP-TE for Point to Multipoint TE LSPs", RFC 4875, "Operations and Management (OAM) Requirements for Point-
May 2007. to-Multipoint MPLS Networks", RFC 4687, September 2006.
[RFC4026] Andersson, L., Madsen, T., "PPVPN Terminology", RFC 4026, [RFC4834] Morin, T., Ed., "Requirements for Multicast in Layer 3
March 2005. Provider-Provisioned Virtual Private Networks (PPVPNs)",
RFC 4834, April 2007.
[RFC3209] Awduche, D, Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa,
Swallow, G. "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, "Extensions to Resource Reservation Protocol - Traffic
December 2001. Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007.
13. Editor's Address [RFC5501] Kamite, Y., Wada, Y., Serbest, Y., Morin, T., and L. Fang,
"Requirements for Multicast Support in Virtual Private LAN
Services", RFC 5501, March 2009.
Jean-Louis Le Roux [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
France Telecom Networks", RFC 5920, July 2010.
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
Email: jeanlouis.leroux@orange-ftgroup.com
14. Contributors' Addresses Authors' Addresses
Jean-Louis (editor)
France Telecom - Orange
Email: jeanlouis.leroux@orange-ftgroup.com
Thomas Morin Thomas Morin
France Telecom France Telecom - Orange
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
Email: thomas.morin@orange-ftgroup.com
Email: thomas.morin@orange-ftgroup.com
Vincent Parfait Vincent Parfait
Orange Business Services France Telecom - Orange, Orange Business Services
1041 Route des Dolines
Sophia Antipolis
06560 Valbonne
FRANCE
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
Snaroyveien 30
Fornebu 1331
NORWAY
Email: lei.wang@telenor.com Email: lei.wang@telenor.com
Yuji Kamite Yuji Kamite
NTT Communications Corporation NTT Communications Corporation
Tokyo Opera City Tower
3-20-2 Nishi Shinjuku, Shinjuku-ku,
Tokyo 163-1421,
JAPAN
Email: y.kamite@ntt.com Email: y.kamite@ntt.com
Shane Amante Shane Amante
Level 3 Communications, LLC Level 3 Communications, LLC
1025 Eldorado Blvd
Broomfield, CO 80021
USA
Email: shane@level3.net
15. Intellectual Property Statement Email: shane@level3.net
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