Subject: [mpls] Scope of Loopback function in draft-ietf-mpls-tp-li-lb-07

From: Greg Mirsky <[email-masked]>
Date: Wed, 5 Oct 2011 11:18:50 -0700

Dear All,
in review of the latest version of LI/LB document a question of what is the
scope of the Loopback function in MPLS came up. The current version of the
document defines scope of the Loopback as:

   - MEPs and MIPs on bi-directional co-routed LSP
   - PW
   - MPLS Section (I believe it should be explicitly characterized as
   bi-directional section)
   - MEPs on bi-directional associated LSP

Thus MIPs of associated LSP that are on both forward and reverse directions
of the same LSP are excluded and not expected to be put in the Loopback
state. I think that such MIP, referred as "coincidental co-routed MIPs" must
be included in scope of the Loopback function. Co-routed bi-directional LSP
can be viewed as special case of associated bi-directional LSP where all
MIPs are not coincidental but intentionally co-routed. But regardless of why
a particular MIP happens to have co-routed character, I think, such MIP can
be set in Loopback. And I propose to explicitly include "coincidental
co-routed" MIPs on associated co-routed LSP in the scope of Loopback
function as defined in the draft-ietf-mpls-tp-li-lb-07.

Regards,
Greg