Subject: draft-gan-fast-reroute

From: [email-masked]
Date: Thu, 18 Oct 2001 11:01:14 +0200

Hello,

What is the use of having the DETOUR object in <draft-gan-fast-reroute>? Let me clarify (see drawing below).

When node 2 establishes the detour to node 4, it sends a PATH message to 
node 4. This PATH message contains the ERO of the detour [node 2 - node 
4]. Since node 2 has calculated this ERO to avoid the downstream router 
(node 3), what is then the use of having the DETOUR object in this PATH 
message? If it serves no purpose, why not just remove it?

        Node1 ====> Node2 ======> Node3 =====> Node4 ======> node 5
                       v                       ^
                       |                       |
                       +-----------------------+

         Francis.

---

From: Irfan Lateef <[email-masked]>
Date: Thu, 18 Oct 2001 10:59:01 -0400

Francis,

See section 4.3 in the draft. It says the detour lsp "MUST" have the
DETOUR object.
The presence of the detour object allows the detour merging node to
differentiate
main LSP from detour LSP which it has to merge with the main LSP.

Irfan

[email-masked] wrote:

>
> Hello,
>
> What is the use of having the DETOUR object in
> <draft-gan-fast-reroute>? Let me clarify (see drawing below).
>
> When node 2 establishes the detour to node 4, it sends a PATH message
> to node 4. This PATH message contains the ERO of the detour [node 2 -
> node 4]. Since node 2 has calculated this ERO to avoid the downstream
> router (node 3), what is then the use of having the DETOUR object in
> this PATH message? If it serves no purpose, why not just remove it?
>

--
Irfan Lateef
Village Networks Inc,