The MPLS WG Archive

[Alia Atlas <aatlas@avici.com>]

Hi Nic & Kireeti,

Why is it necessary to recover a protected LSP between the active PLR and 
the merge node?  That protected LSP will not be used; if one reverts back 
to it, then it can be actively recreated, which has to happen today anyhow.

The merge node can ensure that the primary is recovered for itself and 
downstream.  The PLR can ensure it recovers its backup and the primary itself.

What I am missing in the problem statement?

Thanks,
Alia

At 09:47 AM 10/28/2003, Kireeti Kompella wrote:
>Hi Nic,
>
>On Mon, 27 Oct 2003, Nic Neate wrote:
>
> > The issue with that is not with overlap in the problems they are solving,
> > but in recovering FRR backup and protected LSPs (which may not be being
> > refreshed from upstream) after a restart.  Is this a problem that interests
> > you?
>
>Thanks for clarifying.  I agree that networks will have both GR and
>FRR.  In principle, I agree that this (recovering FRR sessions during
>GR) is a problem that needs to be solved.  However, the premise here
>is that during GR (hopefully a small time window, say a couple of
>minutes), you have a second failure (of a link or a node).
>
>Yes, it's possible to have multiple failures, but the combination of a
>control plane failure recoverable by GR and a link/node failure that
>requires FRR seems remote.
>
>A practical solution (that may not satisfy all) is for GR to recover
>'regular' LSPs sessions, and to re-initiate FRR sessions; and to abort
>GR if a second failure occurs that would have necessitated FRR.
>
>On the other hand, let me not discourage you.  Let's take a look at
>solutions, and see how simple/complex they are before ruling on the
>protocol work.
>
>Kireeti.
>-------