Transcript PPT Version
Requirements
for P2MP Extensions to LDP
draft-leroux-mpls-mp-ldp-reqs-02.txt
Jean-Louis Le Roux (France Telecom)
Thomas Morin (France Telecom)
Vincent Parfait (Equant)
Luyuan Fang (AT&T)
Lei Wang (Telenor)
Yuji Kamite (NTT Communications)
Shane Amante (Level 3 Communications)
IETF 64, Vancouver, MPLS WG, 11/08/2005
Motivations and Objectives (Reminder)
LDP largely deployed for setting up unicast LSPs in MPLS VPN
networks
Emerging requirements for supporting multicast traffic delivery
within these MPLS VPN networks
A relevant approach for multicast traffic delivery over a LDP enabled
MPLS backbone = LDP extensions for setting up Point-ToMultipoint LSPs (P2MP LSPs)
This draft focuses on the LDP approach for setting up P2MP LSPs
It lists a detailed set of requirements for P2MP extensions to LDP
To be used as guidelines when specifying LDP extensions
Requirements summary
MUST allow setting up P2MP LSPs
MUST define a FEC suitable for P2MP forwarding
SHOULD rely on unicast routing table for setting up MPLS shortest path trees
SHOULD support leaf initiated approach for LSP setup and modification
SHOULD avoid data duplication
SHOULD avoid routing loops
SHOULD minimize recovery upon network failure
SHOULD avoid both packet loss and packet duplication during rerouting upon
planned maintenance or metric change: Tension?
MUST avoid traffic replication on LAN interfaces
MUST Support encapsulation in P2P and P2MP TE tunnels
MUST support IPv4/IPv6 (control and forwarding)
MUST support multi-area LSPs
OAM Requirements:
MIB module, connectivity checking and path tracing tool, fast failure detection tool
MUST support Graceful Restart and Fault Recovery
SHOULD scale independently of the number of leaves
SHOULD allow setting up P2MP LSPs over a transit non branch legacy LSR
MUST not impede the operations of unicast LSPs
MAY support Multipoint-to-Multipoint LSPs (MP2MP LSPs)
Changes since last version
Added an application scenario
Multicast VPN traffic delivery on a LDP-enabled MPLS backbone
Clarified routing requirements
Clarified OAM requirements
Need for extensions of P2MP LSP-Ping to LDP P2MP LSPs
Need for a fast data plane failure detection mechanism for P2MP LDP LSPs
Detailed requirements addressed in the P2MP MPLS OAM draft
Added orders of magnitude of the expected #Trees &
#Leaves / Tree
Extracted from the Multicast L3 VPN survey (L3VPN WG)
Added some text on shared trees and MP2MP LSPs
Some rewordings for the sake of clarity
Remaining issues (1)
Need to complement the requirements related to LAN interfaces,
when there are several candidate upstream LSRs
The solution MUST allow selecting a single upstream for a given P2MP
LSP on a LAN
The solution SHOULD support for efficient balancing of a set of P2MP
LSPs among a set of candidates upstream LSRs on a LAN interface
Need to detail routing requirements
Consensus among SPs on this draft that P2MP LDP routing SHOULD
rely on the unicast RIB for setting up MPLS SPT, and not require an IP
multicast routing protocol…
We need to detail the rationales for this requirement
This requires more discussions and WG feedback
Remaining issues (2)
About shared trees
Two main approaches for setting up shared trees in an MPLS network:
– MPLS level: Multipoint-to-Multipoint LSPs (MP2MP LSPs) => need for specific
LDP procedures
– Application level: Combination of a MP2P LSPs with a P2MP LSP (see
Multicast 2547 ID)
Not clear analysis of the pros and cons of the two approaches at the time
being
– Do we need both approaches?
– What would be the gain of the MP2MP approaches versus the added complexity on
LDP?
This is why the requirement for MP2MP LSPs remains OPTIONAL
Of course this may evolve based on WG feedback
Next steps
Need for WG feedback, particularly on open issues
A WG polling in Paris showed a significant interest for this
work
WG doc?
To chairs: What is the status of the WG charter update process?