Re: [Idr] Fwd: New Version Notification for draft-spaghetti-idr-bgp-sendholdtimer-05.txt

[Jeffrey Haas <[e-mail]>]

Donatas,

On Wed, Aug 03, 2022 at 09:19:02PM +0300, Donatas Abraitis wrote:
> A couple of words regarding GR too (might be added):
> 
> "[RFC8538] defines an extension to BGP Graceful Restart that permits the
> Graceful Restart procedures to be
> performed when the BGP speaker receives a NOTIFICATION message or the Hold
> Time expires.
> This document appends BGP Graceful Restart procedures to be performed also
> when Send Hold Time expires."

That's a good start for the side dropping the session due to the
sendholdtimer expiring.

The authors will want to consider what the operational considerations are
for the other side of that connection.  There's no way to tell in the face
of a closed TCP session without related BGP signaling why the session went
down.  If graceful restart is configured, the peer that was (probably)
having problems will start retaining routes and the upstream already knew it
was out of sync.

Jim Uttaro's point in the prior thread was, effectively, how bad are things?
Are you better off retaining a lot of likely good state with some pending
bad state?  Or, is BGP being used in a situation where graceful restart is
simply inappropriate.

While this probably seems obvious, this draft motivates the question about
dropping the session because Stuff Isn't Getting Through.  This bit of
obvious discussion needs to be in the draft.

-- Jeff