RE: RSVP Graceful Restart

[Nurit Sprecher <nurit.sprecher@SeabridgeNetworks.com>]

Hi,
1. There are also issues not necessarily related to multiple errors in the
network. A MP of multiple detours should know which detour should be
refreshed downstream, etc.
2. You say, "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.". 
a. The entire LSP should be tuned with this (upstream detours that are
merged in the restarted node are affected, etc.).  This becomes to be not so
graceful

I think that this interworking of FRR and graceful restart should be
analyzed and the protocol may be needed to support it.
Nurit,


-----Original Message-----
From: Kireeti Kompella [mailto:kireeti@juniper.net]
Sent: Tuesday, October 28, 2003 16:47
To: Nic Neate
Cc: 'mpls@uu.net'; 'ccamp@ops.ietf.org'
Subject: RE: RSVP Graceful Restart

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.
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