On 21/05/13 17:15, John Neiberger wrote:
I guess that's what I get for skimming too quickly. :) thanks! I did
find it interesting that during our testing we saw two different log
messages on the receiving router:
%ROUTING-BGP-5-ADJCHANGE : neighbor a.b.c.d Down - Peer closing down the
session (CEASE notification sent - administrative shutdown) (VRF: default)
%ROUTING-BGP-5-ADJCHANGE : neighbor a.b.c.d Down - Peer closing down the
session (VRF: default)
Sometimes we would see the first, other times we would see the second. I
assume that in the first case we are, in fact, receiving a CEASE
notification. In the second case, I'm thinking maybe the TCP session is
simply being torn down but we have not received a CEASE message.
Either way, it seems that it would be correct behavior to immediately
remove that neighbor's routes from the routing table and BGP table,
No, tearing down the routes on a "bare" TCP session close is
unquestionably wrong IMO.
Think about a peer that has rebooted and is non-stop forwarding, but not
yet ready to re-open a BGP connection. If we send a keepalive (or any
TCP packet) in the window before the peer re-opens a new session to us,
we'll get a RST, and dropping the routes in that situation is wrong.
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