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draft-gan-fast-reroute

  • From: Alia Atlas <aatlas@avici.com>
  • Date: Thu, 11 Oct 2001 20:17:43 -0500
  • Cc: francis.arts@alcatel.be, mpls@UU.NET

At 06:40 PM 10/11/01 -0400, Arthi Ayyangar wrote:
>Hi,
>
>> 
>> I have a question on the RRO handling in <draft-gan-fast-reroute>.
>>  
>>        Node1 ====> Node2 ======> Node3 =====> Node4 ======> Egress
>>                       v                       ^ 
>>                       |                       | 
>>                       +-----------------------+ 
>> 
>> Notation: @(3-2) == IP address of node 3 on the link [node 3 - node 2].
>> 
>> Assume that the link between node 2 and node 3 fails. Then the detour
>> [node 2 - node 4] is taking over. But what does node 2 then send in the
>> RRO object of the RESV message to node 1: Does node 2 continue to send
>> [@(2-1), @(3-2), @(4-3), @(egress-4)] or does node 2 send [@(2-1),
>> @(detour between 4-2), @(egress-4)] or ...? 
>> 
>---> It would send , [@(2-1), @(detour between 4-2), @(egress-4)] 
>as the RRO in the Resv once the detour has taken over.

No, the RRO in the RESV for the Primary LSP would not change.  Node 2 would
continue to send the same RRO as before the failure.

If you look at lsp-tunnel-09.txt, there is a "local protection in-use" flag
which could be set in the IPv4 subobject of the RRO, but the implementation
of draft-gan with which I am familiar doesn't do this.

Alia