[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]
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: November 2006 T. Morin
France Telecom
Vincent Parfait
Equant
Luyuan Fang
AT&T
Lei Wang
Telenor
Yuji Kamite
NTT Communications
Shane Amante
Level 3 Communications
May 2006
Requirements for point-to-multipoint extensions to
the Label Distribution Protocol
draft-ietf-mpls-mp-ldp-reqs-00.txt
Status of this Memo
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
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 1]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
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..............................................8
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..........................9
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...........................................10
5.13. Multi-Area LSPs.............................................10
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.............................11
5.18. Backward Compatibility......................................12
6. Shared Trees...............................................12
6.1. MP2MP LSPs.................................................12
7. Evaluation criteria........................................13
Le Roux et al. Reqs for P2MP extensions to LDP [Page 2]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
7.1. Performances...............................................13
7.2. Complexity and Risks.......................................13
8. Security Considerations....................................13
9. Acknowledgments............................................13
10. References.................................................14
11. Editor Address.............................................15
12. Contributors Addresses.....................................15
13. Intellectual Property Statement............................16
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
Leaf LSR: Egress LSR of a P2MP 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-00.txt May 2006
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
applications 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.
- Section 6 finally discusses group communication.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 4]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
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 arbitrary addition or removal
of leaves associated with a P2MP LSP.
The P2MP LDP mechanism MUST interoperate seamlessly with existing P2P
and MP2P LDP mechanisms.
It is of paramount importance that the P2MP LDP mechanism MUST NOT
impede the operation of existing P2P/MP2P LSPs.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 5]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
Note that 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 must be
maintained by a LSR. Detailed requirements for MP2MP LSPs are left
for further study.
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].
MP2P LDP LSPs are setup between PE routers to carry unicast VPN
traffic.
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).
Le Roux et al. Reqs for P2MP extensions to LDP [Page 6]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
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.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 7]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
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. It is RECOMMENDED that these
operations be leaf-initiated.
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).
5.7. Avoiding loops
The P2MP LDP mechanism SHOULD have a mechanism to avoid routing loops
even during transient events.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 8]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
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 must 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, or the addition of links or nodes.
Traffic disruption SHOULD be minimized as much as possible during
such rerouting. It SHOULD be feasible to avoid packet loss during
such rerouting.
Unnecessary data duplication during such rerouting SHOULD also be
minimized as much as possible.
Note that there is likely to be a tension between packet loss
minimization and packet duplication minimization objectives.
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 SHOULD be
minimized as much as possible during such rerouting. It SHOULD be
feasible to avoid packet loss during such rerouting.
Unnecessary traffic duplication during such rerouting SHOULD also be
minimized as much as possible.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 9]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
Note that there is likely to be a tension between packet loss
minimization and packet duplication minimization objectives.
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 P2MP LDP sessions.
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.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 10]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
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
[P2MP-OAM-REQ].
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 SHOULD avoid single points of failures or propose some
technical solutions for a failover mechanism.
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
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].
Le Roux et al. Reqs for P2MP extensions to LDP [Page 11]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
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 interoperate seamlessly 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:
- 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 the root PE to all PEs of the
Group (see also [2547-MCAST]).
- 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
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. MP2MP LSPs
*Editorial note: There is currently no clear analysis of the gain of
the MP2MP MPLS approach (with the potential impact on LDP), versus
using application-level shared trees. This is why the requirement for
MP2MP LSPs is currently optional*
The P2MP LDP mechanism MAY allow setting up MP2MP LSP. A MP2MP LSP is
a LSP connecting a group of Leaf LSRs acting indifferently as Ingress
Le Roux et al. Reqs for P2MP extensions to LDP [Page 12]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
or Egress LSRs. Traffic sent by any Leaf LSRs is received by all
other Leaf LSRs of the group. A sender LSR does not receive back the
traffic sent.
All detailed requirements for P2MP LSPs listed in section 5, apply
equally to MP2MP LSPs. Particularly it is RECOMMENDED that the size
of MP2MP state on a LSR, for one particular MP2MP LSP, depend only on
the number of adjacent LSRs on the LSP, and not on the number of Leaf
LSRs.
Additional detailed requirements specific to MP2MP LSPs are left for
further study.
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 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.
The proposed solution SHOULD not require deploying a new routing
protocol.
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.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 13]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
We would also like to thank authors of [P2MP-TE-REQ] from which some
text of this document has been inspired.
10. References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78, RFC
3667, February 2004.
[BCP79] Bradner, S., "Intellectual Property Rights in IETF
Technology", RFC 3979, March 2005.
[LDP] L. Andersson, P. Doolan, N. Feldman, A. Fredette, B. Thomas,
"LDP Specification", RFC 3036, January 2001
[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
[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.
[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.
[2547-MCAST] E. Rosen, R. Aggarwal, et. al., "Multicast in MPLS/BGP
IP VPNs", draft-ietf-l3vpn-2547bis-mcast, work in progress.
[P2MP-OAM-REQ] S. Yasukawa, A. Farrel, D. King, T. Nadeau, "OAM
Requirements for Point-To-Multipoint MPLS Networks", draft-ietf-mpls-
p2mp-oam-reqs, work in progress.
[VPLS-MCAST] R.Aggarwal, Y Kamite, L Fang, VPLS Multicast draft-
ietf-l2vpn-vpls-mcast, work in progress.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 14]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
11. Editor Address
Jean-Louis Le Roux
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
Email: jeanlouis.leroux@francetelecom.com
12. Contributors Addresses
Thomas Morin
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
Email: thomas.morin@francetelecom.com
Vincent Parfait
EQUANT
1041 Route des Dolines
Sophia Antipolis
06560 Valbonne
FRANCE
Email: vincent.parfait@equant.com
Luyuan Fang
AT&T
200 Laurel Avenue
Middletown, NJ 07748
USA
Email: luyuanfang@att.com
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
Le Roux et al. Reqs for P2MP extensions to LDP [Page 15]
Internet Draft draft-ietf-mpls-mp-ldp-reqs-00.txt May 2006
1025 Eldorado Blvd
Broomfield, CO 80021
USA
Email: shane@level3.net
13. Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Le Roux et al. Reqs for P2MP extensions to LDP [Page 16]
Html markup produced by rfcmarkup 1.129b, available from
https://tools.ietf.org/tools/rfcmarkup/