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Versions: (draft-leroux-mpls-mp-ldp-reqs) 00
01 02 03 04 05 06 07 08 RFC 6348
Network Working Group J.-L. Le Roux (Editor)
Internet Draft France Telecom
Category: Informational
Expires: September 2007 T. Morin
France Telecom
Vincent Parfait
Orange Business Services
Luyuan Fang
Cisco Systems, Inc.
Lei Wang
Telenor
Yuji Kamite
NTT Communications
Shane Amante
Level 3 Communications
March 2007
Requirements for Point-To-Multipoint Extensions to
the Label Distribution Protocol
draft-ietf-mpls-mp-ldp-reqs-02.txt
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Le Roux et al. Reqs for P2MP extensions to LDP [Page 1]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
Abstract
This document lists a set of functional requirements for Label
Distribution Protocol (LDP) extensions for setting up point-to-
multipoint (P2MP) Label Switched Paths (LSP), in order to deliver
point-to-multipoint applications over a Multi Protocol Label
Switching (MPLS) infrastructure. It is intended that solutions that
specify LDP procedures for setting up P2MP LSP satisfy these
requirements.
Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119.
Table of Contents
1. Terminology.................................................3
2. Introduction................................................4
3. Problem Statement and Requirements Overview.................5
3.1. Problem Statement...........................................5
3.2. Requirements overview.......................................5
4. Application scenario........................................6
5. Detailed Requirements.......................................7
5.1. P2MP LSPs...................................................7
5.2. P2MP LSP FEC................................................7
5.3. P2MP LDP routing............................................8
5.4. Setting up, tearing down and modifying P2MP LSPs............8
5.5. Label Advertisement.........................................8
5.6. Data Duplication............................................8
5.7. Avoiding loops..............................................9
5.8. P2MP LSP Re-routing.........................................9
5.8.1. Rerouting upon Network Failure..............................9
5.8.2. Rerouting on a Better Path..................................9
5.8.3. Rerouting upon Planned Maintenance.........................10
5.9. Support for LAN interfaces.................................10
5.10. Support for encapsulation in P2P and P2MP TE tunnels.......10
5.11. Label spaces...............................................10
5.12. IPv4/IPv6 support..........................................11
5.13. Multi-Area LSPs............................................11
5.14. OAM........................................................11
5.15. Graceful Restart and Fault Recovery........................11
5.16. Robustness.................................................11
5.17. Scalability................................................11
5.17.1. Orders of magnitude of the expected numbers of P2MP
LSPs in operational networks.............................12
5.18. Backward Compatibility.....................................12
6. Shared Trees...............................................12
6.1. Requirements for MP2MP LSPs................................13
7. Evaluation criteria........................................14
7.1. Performances...............................................14
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Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
7.2. Complexity and Risks.......................................14
8. Security Considerations....................................14
9. Acknowledgments............................................14
10. References.................................................14
10.1. Normative references.......................................14
10.2. Informative references.....................................15
11. Editor Address.............................................15
12. Contributors Addresses.....................................16
13. Intellectual Property Statement............................17
1. Terminology
LSR: Label Switching Router
LSP: MPLS Label Switched Path
Ingress LSR: Router acting as a sender of an LSP
Egress LSR: Router acting as a receiver of an LSP
P2P LSP: A LSP that has one unique Ingress LSR and one unique
Egress LSR
MP2P LSP: A LSP that has one or more Ingress LSRs and one unique
Egress LSR
P2MP LSP: A LSP that has one unique Ingress LSR and one or more
Egress LSRs
MP2MP LSP: A LSP that as one or more Leaf LSRs acting
indifferently as Ingress or Egress LSR
Leaf LSR: Egress LSR of a P2MP LSP or Ingress/Egress LSR of a
MP2MP LSP
Transit LSR: A LSR of a P2MP LSP that has one or more downstream
LSRs
Branch LSR: A LSR of a P2MP LSP that has more than one downstream
LSR
Bud LSR: A LSR of a P2MP LSP that is an egress but also has one or
more directly connected downstream LSRs
Le Roux et al. Reqs for P2MP extensions to LDP [Page 3]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
2. Introduction
Many operators have deployed LDP [LDP] for setting up point-to-point
(P2P) and multipoint-to-point (MP2P) LSPs, in order to offer point-to
-point services in MPLS backbones.
There are emerging requirements for supporting delivery of point-to-
multipoint applications in MPLS backbones, such as those defined in
[L3VPN-MCAST-REQ] and [L2VPN-MCAST-REQ].
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
with MPLS traffic replication at some Branch LSRs.
RSVP-TE extensions for setting up Point-To-Multipoint Traffic
Engineered LSPs (P2MP TE LSPs), have been defined in [P2MP-TE-RSVP].
They meet requirements expressed in [P2MP-TE-REQ]. This approach is
useful, in network environments where P2MP Traffic Engineering
capabilities are needed (Optimization, QoS, Fast recovery).
However for operators who want to support point-to-multipoint traffic
delivery on an MPLS backbone, without Traffic Engineering needs, and
have already deployed LDP for P2P traffic, an interesting and useful
approach would be to rely on LDP extensions in order to setup 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.
This document focuses on the LDP approach for setting up P2MP LSPs.
It lists a detailed set of requirements for P2MP extensions to LDP,
so as to deliver P2MP traffic over a LDP-enabled MPLS infrastructure.
These requirements should be used as guidelines when specifying LDP
extensions. It is intended that solutions that specify LDP procedures
for P2MP LSP setup, satisfy these requirements.
Note that generic requirements for P2MP extensions to MPLS are out of
the scope of this document. Rather this document describes solution
specific requirements related to LDP extensions in order to set up
P2MP LSPs.
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
scope of this document. The objective is not to compare these
mechanisms but rather to focus on the requirements for an LDP
extension approach.
The document is structured as follows:
- Section 3 points out the problem statement;
- Section 4 illustrates an application scenario;
- Section 5 addresses detailed requirements for P2MP LSPs;
- Section 6 finally discusses group communication, and
requirements for MP2MP LSPs.
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Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
3. Problem Statement and Requirements Overview
3.1. Problem Statement
Many operators have deployed LDP [LDP] for setting up P2P and MP2P
MPLS LSPs 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 for supporting multicast traffic delivery within these
VPN infrastructures ([L3VPN-MCAST-REQ] and [L2VPN-MCAST-REQ]). For
various reasons, including consistency with P2P applications, and
taking full advantages of MPLS network infrastructure, it would be
highly 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, but such an approach may be sub-optimal since it would
result in data replication at the ingress LSR, and bandwidth
inefficiency (duplicate data traffic within the network). Hence new
mechanisms are required that would allow traffic from an Ingress LSR
to be efficiently delivered to a number of Egress LSRs in an MPLS
backbone, avoiding duplicate copies of a packet on a given link.
Such efficient traffic delivery requires setting up P2MP LSPs. A P2MP
LSP is an LSP starting at an Ingress LSR, and ending on a set of one
or more Egress LSRs. Traffic sent by the Ingress LSR is replicated on
one or more Branch LSRs down to Egress LSRs.
RSVP-TE extensions for setting up P2MP TE LSPs, which meet
requirements expressed in [P2MP-TE-REQ], have been defined in [P2MP-
TE-RSVP]. This approach is useful, in network environments where
Traffic Engineering capabilities are required. However, for operators
that deployed LDP for setting up PE-to-PE unicast MPLS LSPs, and
without the need for traffic engineering, an interesting approach
would be using LDP extensions for setting up P2MP LSPs.
The following gives a set of guidelines that a specification of LDP
extensions for setting up P2MP LSPs should follow.
3.2. Requirements overview
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
replication at some Branch LSRs.
The P2MP LDP mechanism MUST allow the addition or removal of leaves
associated with a P2MP LSP.
The P2MP LDP mechanism MUST co-exist with current LDP mechanisms and
inherit its capability sets from [LDP]. It is of paramount importance
that the P2MP LDP mechanism MUST NOT impede the operation of existing
P2P/MP2P LSPs.
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The P2MP LDP mechanism MAY also allow setting up multipoint-to-
multipoint (MP2MP) LSPs connecting a group of Leaf LSRs acting
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
LSR.
4. Application Scenario
Figure 1 below illustrates an LDP enabled MPLS provider network, used
to carry both unicast and multicast traffic of VPN customers
following for instance the architecture defined in [2547-MCAST] for
BGP/MPLS VPNs, or the one defined in [VPLS-MCAST].
A set of MP2P LDP LSPs are setup between PE routers to carry unicast
VPN traffic within the MPLS backbone.
A set of P2MP LDP LSPs are setup between PE routers acting as Ingress
LSRs and PE routers acting as Egress LSRs, so as to support multicast
VPN traffic delivery within the MPLS backbone.
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
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
non-branch transit LSRs, they forward MPLS traffic sent by P1 to PE3
and PE4 respectively.
PE1
*| *** P2MP LDP LSP
*| ****
P1-----PE2
*/ \*
*/ \*
*****/ \* ****
PE3----P2 P3----PE4
| |
| |
| |
PE5 PE6
Figure 1: P2MP LSP from PE1 to PE2, PE3, PE4.
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
replicate traffic received from P1, to PE3 and PE5, and to PE4 and
PE6 respectively (see figure 2 below).
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Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
PE1
*| *** P2MP LDP LSP
*| ****
P1-----PE2
*/ \*
*/ \*
*****/ \* ***
PE3----P2 P3----PE4
*| |*
*| |*
*| |*
PE5 PE6
Figure 2: Attachment of PE5 and PE6.
5. Detailed Requirements
5.1. P2MP LSPs
The P2MP LDP mechanism MUST support setting up P2MP LSPs.
Data plane aspects related to P2MP LSPs are those already defined in
[P2MP-TE-REQ]. 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 specific aspects related to P2MP LSPs is the action
required at a Branch LSR, where data replication occurs.
Incoming labelled data is appropriately replicated to several
outgoing interfaces which may use different labels. Only one copy of
a packet MUST be sent on a given link of a P2MP LSP.
A P2MP LSP MUST be identified by a constant and unique identifier
within the whole LDP domain, whatever the number of leaves, which
may vary dynamically.
This identifier will be used so as to add/remove leaves to/from the
P2MP tree.
5.2. P2MP LSP FEC
As with P2P MPLS technology [LDP], traffic MUST be classified 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 the same
P2MP LSP.
As such, a solution MUST specify a FEC that is suitable for P2MP
forwarding. Such P2MP FEC MUST be distinguished clearly from the
existing P2P FEC.
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5.3. P2MP LDP routing
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
information maintained in LSR Routing Information Bases (RIB).
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.
5.4. Setting up, tearing down and modifying P2MP LSPs
The P2MP LDP mechanism MUST support the establishment, maintenance
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
network and a large amount of leaf LSRs for a single P2MP LSP.
In order to scale well with a large number of leaves it is
RECOMMENDED to follow a leaf-initiated P2MP LSP setup approach. For
that purpose, leaves will have to be aware of the P2MP LSP
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
of this document.
The P2MP LDP mechanism MUST allow the dynamic addition and removal of
leaves to and from a P2MP LSP, without any restriction (provided
there is network connectivity). It is RECOMMENDED that these
operations be leaf-initiated.
These operations MUST not impact the data transfer (packet loss,
duplication, delay) towards other leaves. It is RECOMMENDED that
these operations do not cause any additional processing except on the
path from the added/removed Leaf LSR to the Branch LSR.
5.5. Label Advertisement
The P2MP LDP mechanism SHOULD support downstream unsolicited label
advertisement mode. This is well suited to a leaf-initiated approach
and is consistent with P2P/MP2P LDP operations.
5.6. Data Duplication
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
be detrimental for certain applications. Hence, data duplication
SHOULD be avoided as much as possible, and limited to (hopefully
rare) transitory conditions.
Note, in particular, that data duplication might occur if P2MP LSP
rerouting is being performed (See also section 5.8).
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5.7. Avoiding loops
The P2MP LDP mechanism SHOULD have a mechanism to avoid routing loops
even during transient events.
Furthermore, the P2MP LDP mechanism MUST avoid routing loops that may
trigger unexpected non-localized exponential growth of traffic. Note
that any loop-avoidance mechanism MUST respect scalability
requirements.
5.8. P2MP LSP Re-routing
The P2MP LDP mechanism MUST support the rerouting of a P2MP LSP in
the following cases:
- Network failure (link or node);
- A better path exists (e.g. new link, metric change);
- Planned maintenance.
Given that P2MP LDP routing should rely on the RIB, the achievement
of the following requirements also implies the underlying routing
protocols (IGP, etc.).
5.8.1. Rerouting upon Network Failure
The P2MP LDP mechanism MUST allow for rerouting of a P2MP LSP in case
of link or node failure(s). The rerouting time SHOULD be minimized as
much as possible so as to reduce traffic disruption.
A mechanism MUST be defined to prevent constant P2MP LSP teardown and
rebuild which may be caused by the instability of a specific
link/node in the network.
5.8.2. Rerouting on a Better Path
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 metric change, a link repair, or the addition of links or nodes.
Traffic disruption and data duplication SHOULD be minimized as much
as possible during such rerouting.
There is actually a tension between packet loss minimization and
packet duplication minimization objectives.
It SHOULD be feasible to avoid either data duplication or packet loss
during such rerouting.
A solution MAY provide the operator with means to choose between
favoring avoiding packet loss at the expense of potential packet
duplication, and favoring avoiding duplication against packet loss.
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5.8.3. Rerouting upon Planned Maintenance
The P2MP LDP mechanism MUST support planned maintenance operations.
It MUST be possible to reroute a P2MP LSP before a link/node is
deactivated for maintenance purposes.
Traffic disruption and data duplication SHOULD be minimized as much
as possible during such planned maintenance.
There is actually a tension between packet loss minimization and
packet duplication minimization objectives.
It SHOULD be feasible to avoid either data duplication or packet loss
during such rerouting.
A solution MAY provide the operator with means to choose between
favoring avoiding packet loss at the expense of packet duplication,
and favoring avoiding duplication against packet loss.
5.9. Support for LAN interfaces
The P2MP LDP mechanism MUST provide a way for a Branch LSR to send a
single copy of the data onto an Ethernet LAN interface and reach
multiple adjacent downstream nodes. This requires that the same label
be negotiated with all downstream LSRs for the LSP.
When there are several candidate upstream LSRs on a LAN interface,
the P2MP LDP mechanism MUST provide a way for all downstream LSRs 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 for an efficient
balancing of a set of P2MP LSPs among a set of candidate upstream
LSRs on a LAN interface.
5.10. Support for encapsulation in P2P and P2MP TE tunnels
The P2MP LDP mechanism MUST support nesting P2MP LSPs into P2P and
P2MP TE tunnels.
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
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
LAN interfaces, this requires that the same LDP label be negotiated
with all downstream LSRs for the P2MP LDP LSP.
5.11. Label spaces
Labels for P2MP LSPs and P2P/MP2P LSPs MAY be assigned from shared or
dedicated label spaces.
Note that dedicated label spaces will require the establishment of
separate P2P and P2MP LDP sessions.
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Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
5.12. IPv4/IPv6 support
The P2MP LDP mechanism MUST be equally applicable to IPv4 and IPv6
traffic. Likewise, it SHOULD be possible to convey both kinds of
traffic in a given P2MP LSP facility.
Also the P2MP LDP mechanism MUST support the establishment of LDP
sessions over both IPv4 and IPv6 control planes.
5.13. Multi-Area LSPs
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
area as the Ingress LSR. This SHOULD be possible without requiring
the advertisement of Ingress LSRs' addresses across IGP areas.
5.14. OAM
LDP management tools ([LDP-MIB], etc.) MUST be enhanced to support
P2MP LDP extensions. This may yield a new MIB module, which may
possibly be inherited from the LDP MIB.
In order to facilitate correct management, P2MP LDP LSPs MUST have
unique identifiers, otherwise it is impossible to determine which LSP
is being managed.
Built-in diagnostic tools MUST be defined to check the connectivity,
trace the path and ensure fast detection of data plane failures on
P2MP LDP LSPs.
Further and precise requirements and mechanisms for P2MP MPLS OAM
purpose are out of the scope of this document and are addressed in
[RFC4687].
5.15. Graceful Restart and Fault Recovery
LDP Graceful Restart mechanisms [LDP-GR] and Fault Recovery [LDP-FT]
mechanisms SHOULD be enhanced to support P2MP LDP LSPs.
5.16. Robustness
A solution MUST avoid single points of failures provided there is
enough network connectivity.
5.17. Scalability
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 the following:
- number of Leaf LSRs per P2MP LSP;
- number of Downstream LSRs per Branch LSR;
- number of P2MP LSPs per LSR.
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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
particular LSP, depend only on the number of adjacent LSRs on the
LSP.
5.17.1. Orders of magnitude of the expected numbers of P2MP LSPs in
operational networks
Typical orders of magnitude that we expect should be supported are:
- tens of thousands of P2MP trees spread out across core network
routers;
- hundreds, or a few thousands, of leaves per tree;
See also section 4.2 of [L3VPN-MCAST-REQ].
5.18. Backward Compatibility
In order to allow for a smooth migration, the P2MP LDP mechanism
SHOULD offer as much backward compatibility as possible. In
particular, the solution SHOULD allow the setup of a P2MP LSP along
non-Branch Transit LSRs that do not support P2MP LDP extensions.
Also, the P2MP LDP solution MUST co-exist with current LDP mechanisms
and inherit its capability sets from [LDP]. The 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 P2MP LSPs
to be signalled on the same interface.
6. Shared Trees
For traffic delivery between a group of N Leaf LSRs which are acting
indifferently as Ingress or Egress LSRs, it may be useful to
setup a shared tree connecting all these LSRs, instead of having N
P2MP LSPs. This would reduce the amount of control and forwarding
state that has to be maintained on a given LSR.
There are actually two main options for supporting such shared trees:
- This could rely on the applications protocols that use LDP
LSPs. A shared tree could consist of the combination of a
MP2P LDP LSP from Leafs LSRs to a given root node, with a P2MP
LSP from this root to all Leaf LSRs. For instance with
Multicast L3 VPN applications, it would be possible to build a
shared tree by combining (see section 6.6 of [2547-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 PEs of the
Group.
- Or this could rely on a specific LDP mechanism allowing to
setup multipoint-to-multipoint MPLS LSPs (MP2MP LSPs).
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The former approach (Combination of MP2P and P2MP LSPs at the
application level) is out of the scope of this document while the
latter (MP2MP LSPs) belong to the scope of this document.
Requirements for the set up of MP2MP LSPs are listed below.
6.1. Requirements for MP2MP LSPs
A MP2MP LSP is a LSP connecting a group of Leaf LSRs acting
indifferently as Ingress or Egress LSRs. Traffic sent by any Leaf
LSRs is received by all other Leaf LSRs of the group.
Procedures for setting up MP2MP LSPs SHOULD be specified.
An implementation that support P2MP LDP LSPs MAY also support MP2MP
LDP LSP.
The MP2MP LDP procedures MUST not impede the operations of P2MP LSP.
Requirements for P2MP LSPs set forth in section 5 apply equally to
MP2MP LSPs. Particular attention should be given on the below
requirements:
- The solution MUST support recovery upon link and transit node
failure and there MUST NOT be any single point of failure (provided
network connectivity is redundant). Note that transit node
failure recovery is likely to be more complex to handle with MP2MP
LSPs than with P2MP LSPs;
- 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:
- It is RECOMMENDED that a MP2MP MPLS LSP follow shortest paths to a
specific LSR called root LSR;
- It is RECOMMENDED to define several root LSRs (e.g. a primary and
a backup) to ensure redundancy upon root LSR failure;
- The receiver SHOULD not receive back a packet it has sent on the
MP2MP LSP;
- The solution SHOULD avoid that all traffic between any pair of
leaves is traversing a root LSR, and SHOULD as much as possible
minimize the distance between two leaves (similarly to PIM-Bidir
trees);
- It MUST be possible to check connectivity of a MP2MP LSP in both
directions.
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Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
7. Evaluation criteria
7.1. Performances
The solution will be evaluated with respect to the following
criteria:
(1) Time to add or remove a Leaf LSR;
(2) Time to repair a P2MP LSP in case of link or node
failure;
(3) Scalability (state size, number of messages, message size).
Particularly the P2MP LDP mechanism SHOULD be designed with as key
objective to minimize the additional amount of state and additional
processing required in the network when deploying P2MP LDP.
Also, the P2MP LDP mechanism SHOULD be designed so that convergence
times in case of link or node failure are minimized, in order to
limit traffic disruption.
7.2. Complexity and Risks
The proposed solution SHOULD not introduce complexity to the current
LDP operations to such a degree that it would affect the stability
and diminish the benefits of deploying such P2MP LDP solution.
8. Security Considerations
This document does not introduce any new security issue beyond those
inherent to LDP, and a P2MP LDP solution may rely on the security
mechanisms defined in [LDP] (e.g. TCP MD5 Signature).
9. Acknowledgments
We would like to thank Christian Jacquenet (France Telecom),
Hitoshi Fukuda (NTT Communications), Ina Minei (Juniper), Dean
Cheng (Cisco Systems), and Benjamin Niven-Jenkins (British Telecom),
for their highly useful comments and suggestions.
We would also like to thank authors of [P2MP-TE-REQ] from which some
text of 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.
[LDP] L. Andersson, P. Doolan, N. Feldman, A. Fredette, B. Thomas,
"LDP Specification", RFC 3036, January 2001
Le Roux et al. Reqs for P2MP extensions to LDP [Page 14]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
[LDP-MIB] J. Cuchiarra et al. "Definitions of Managed Objects for the
Multiprotocol Label Switching (MPLS), Label Distribution Protocol
(LDP)", RFC3815, June 2004.
[LDP-GR] M. Leelanivas, Y. Rekhter, R. Aggarwal, " Graceful Restart
Mechanism for Label Distribution Protocol" RFC3478, February 2003.
[LDP-FT] A. Farrel, " Fault Tolerance for the Label Distribution
Protocol (LDP)", RFC3479, February 2003.
10.2. Informative references
[L3VPN-MCAST-REQ] T. Morin, Ed., "Requirements for Multicast in L3
Provider-Provisioned VPNs", draft-ietf-l3vpn-ppvpn-mcast-reqts, work
in progress.
[L2VPN-MCAST-REQ] Y. Kamite et al. "Requirements for Multicast
Support in Virtual Private LAN Services", draft-ietf-l2vpn-vpls-
mcast-reqts, work in progress.
[2547-MCAST] E. Rosen, R. Aggarwal, et. al., "Multicast in MPLS/BGP
IP VPNs", draft-ietf-l3vpn-2547bis-mcast, work in progress.
[VPLS-MCAST] R.Aggarwal, Y Kamite, L Fang, VPLS Multicast draft-
ietf-l2vpn-vpls-mcast, work in progress.
[RFC4687] S. Yasukawa, A. Farrel, D. King, T. Nadeau, "OAM
Requirements for Point-To-Multipoint MPLS Networks", RFC4687,
September 2006.
[P2MP-TE-REQ] S. Yasukawa, et. al., "Requirements for Point-to-
Multipoint capability extension to MPLS", RFC4461, April 2006.
[P2MP-TE-RSVP] R. Aggarwal, D. Papadimitriou, S. Yasukawa, et. al..,
"Extensions to RSVP-TE for Point to Multipoint TE LSPs", draft-ietf-
mpls-rsvp-te-p2mp, work in progress.
11. Editor Address
Jean-Louis Le Roux
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
Email: jeanlouis.leroux@orange-ftgroup.com
Le Roux et al. Reqs for P2MP extensions to LDP [Page 15]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
12. Contributors Addresses
Thomas Morin
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
Email: thomas.morin@orange-ftgroup.com
Vincent Parfait
Orange Business Services
1041 Route des Dolines
Sophia Antipolis
06560 Valbonne
FRANCE
Email: vincent.parfait@orange-ftgroup.com
Luyuan Fang
Cisco Systems, Inc.
300 Beaver Brook Road
Boxborough, MA 01719
USA
EMail: lufang@cisco.com Luyuan Fang
Lei Wang
Telenor
Snaroyveien 30
Fornebu 1331
NORWAY
Email: lei.wang@telenor.com
Yuji Kamite
NTT Communications Corporation
Tokyo Opera City Tower
3-20-2 Nishi Shinjuku, Shinjuku-ku,
Tokyo 163-1421,
JAPAN
Email: y.kamite@ntt.com
Shane Amante
Level 3 Communications, LLC
1025 Eldorado Blvd
Broomfield, CO 80021
USA
Email: shane@level3.net
Le Roux et al. Reqs for P2MP extensions to LDP [Page 16]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-02.txt March 2007
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