Subject: RE: Question regarding multi-homed prefix LFA computation

From: Kui Zhang <[email-masked]>
Date: Fri, 15 Feb 2008 19:52:30 +0800

The remaining problem is the relation between node protecting and link
protecting inequality. Please read the following words:

As for node-protecting alternatives, I read the following description in
section 3.3.  Broadcast and NBMA Links:

“Because the shortest path from the pseudo-node goes through E, if a

   loop-free alternate from a neighbor N is node-protecting, the

   alternate will also be link-protecting unless the router S can only

   reach the alternate neighbor N via the same pseudo-node.”

This means only the SRLG of broadcast and NBMA links make the
node-protecting LFA failed to provide link protection. Except for this,
node-protecting alternate should always be link protecting. Is that right?

zhangkui

_______________________________________________
rtgwg mailing list
[email-masked]
http://www.ietf.org/mailman/listinfo/rtgwg

---

From: "Alia Atlas" <[email-masked]>
Date: Fri, 15 Feb 2008 10:04:12 -0500

You mean, except for the case where the node-protecting LFA isn't
link-protecting because it goes through the same pseudo-node, it will be
link-protecting?  Yes - but that's not a very meaningful statement.

For point-to-point interfaces, an LFA that is node-protecting is always
link-protecting.

Alia

2008/2/15 Kui Zhang <[email-masked]>:

> "Because the shortest path from the pseudo-node goes through E, if a
>
>    reach the alternate neighbor N via the same pseudo-node."
>
>
>