RE: TE metric and graceful restart

[Kireeti Kompella <kireeti@juniper.net>]

On Sat, 27 Apr 2002, Zafar Ali wrote:

> The reason that I understood this as a MAY case is that a node that saves
> bandwidth usage state information locally is able to determine (or
> estimate) the amount of unreserved resources immediately upon start-up. In
> which case it MAY advertise the saved (projected) value(s) during the
> graceful restart period.

Attractive as that may be, life is not so simple.  The process of
recovery for signaling is complex enough without having new LSPs set
up during recovery.  The idea of discouraging LSPs during recovery is
not just that the recovering node doesn't know its unreserved bandwidth,
but that it wants to complete recovery before setting up new LSPs.

A simple example is that the recovering node X uses per-box labels,
gets a new LSP request while recovering, and allocates label L to that
request.  But L is already in use for an existing LSP ....  One can
work around this particular example, but keeping it simple seems like
a good initial goal.

At least, that's my take.

Kireeti.