The MPLS WG Archive

[lidefeng <77cronux.leed0621@huawei.com>]

In section 3.4 of draft-ietf-mpls-rsvp-te-p2mp-00.txt, it says that "All LSRs need to  process the ERO corresponding to the first P2P sub-LSP. A LSR needs  to process a P2P sub-LSP descriptor for a subsequent P2P sub-LSP only if the first hop in the corresponding SERO is a local address of that LSR. The branch LSR that is the first hop of a SERO propagates the   corresponding P2P sub-LSP downstream."

Does  it mean that an LSR received the Path message with one ERO and several SEROs, if all the SEROs don't include this particular LSR, this particular need't process all these SEROs? For example,  In the case of the p2mp tree of figure 1 in draft-ietf-mpls-rsvp-te-p2mp-00.txt, LSR H encode the P2P sub-LSP explicit  routes in the Path message sent to LSR I:
      P2P sub-LSP-Q:   ERO = {I, M, Q}, P2P_SUB_LSP Object-Q,
      P2P sub-LSP-R:   SERO = {Q, R}, P2P_SUB_LSP Object-R,

then, LSR I need only process "P2P sub-LSP-Q:   ERO = {I, M, Q}, P2P_SUB_LSP Object-Q,", needn't process "P2P sub-LSP-R:   SERO = {Q, R}, P2P_SUB_LSP Object-R,"? if it is right, what is the justification to carry the SERO?

And what does "The branch LSR that is the first hop of a SERO propagates the   corresponding P2P sub-LSP downstream." mean? it means that LSR Q propagates the  corresponding P2P sub-LSP downstream when LSR I receives the Path message sented by LSR H? and it is clear that at this time LSR Q doesn't receive the Path message yet, how can it propogate the P2P sub-LSP downstream? Or this sentence means something else? 

Regards

Defeng Li




----- Original Message ----- 
From: <Internet-Drafts@ietf.org>
To: <i-d-announce@ietf.org>
Cc: <mpls@ietf.org>
Sent: Wednesday, November 17, 2004 5:13 AM
Subject: [mpls] I-D ACTION:draft-ietf-mpls-rsvp-te-p2mp-00.txt


> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Multiprotocol Label Switching Working Group of the IETF.
> 
> Title : Extensions to RSVP-TE for Point to Multipoint TE LSPs
> Author(s) : R. Aggarwal, et al.
> Filename : draft-ietf-mpls-rsvp-te-p2mp-00.txt
> Pages : 45
> Date : 2004-11-16
> 
> This document describes extensions to Resource Reservation Protocol -
>    Traffic Engineering (RSVP-TE) for the setup of point-to-multipoint
>    (P2MP) Label Switched Paths (LSPs) in Multi-Protocol Label Switching
>    (MPLS) and Generalized MPLS (GMPLS) networks.  The solution relies on
>    RSVP-TE without requiring a multicast routing protocol in the Service
>    Provider core. Protocol elements and procedures for this solution are
>    described. There can be various applications for P2MP TE LSPs such as
>    IP multicast. Specification of how such applications will use a P2MP
>    TE LSP is outside the scope of this document.
> 
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