> Just guessing - you're seeing these events between midnight
> and 5 am?Hm, couldn't reist this one: "which time zone"?
Just hinting that even though it's that time interval in the US, local
time is different in other places around the world, so if this is
causing disturbance, others are probably being hit in their working
hours.
Heh, the "perpetual global maintenance window syndrome", eh? A
very useful concept...
Besides, I was under the impression that to activate a new outbound
roting policy on a Cisco, you could just modify / replace it, but that
you would still have to dorouter#clear ip bgp xxx soft out
to activate it. This means that the policy for an existing peer can
be modified without having to remove the peering and reenable it
shortly thereafter (something which would cause needless route
flapping).
Somewhat true. The new policy would not be applied to routes that
were already in the table, but would be applied to any adds/withdrawals
that occur once the policy changes are placed in the configuration.
This fact has a synergistic effect when you're making changes that
affect lots of sessions. So a policy change made a significant time
before a clear or soft clear could in fact result in flaps.
Also consider: there are a lot of routers using traditional ACL's in their
policies (as opposed to things like prefix-lists which have more granular
editing features) which would necessitate removing the ACL completely and
rewriting it with updated lines. Due to the above, a potential for leaks
exists unless the session is either shutdown or deleted while acl's are
being modified.
If the sequence of events in a configuration script is not well thought
out, the result could be what Ratul has observed in his study.