[c-nsp] BGP Cease notifications with Graceful Restart

[John Neiberger]

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, which
is not what we were seeing. The routes were not being removed from the
routing table until the graceful restart timer expired. It was certainly
unexpected.

Thanks again!
John


On Tue, May 21, 2013 at 9:56 AM, Phil Mayers <p.mayers at imperial.ac.uk>wrote:

> On 21/05/13 16:31, John Neiberger wrote:
>
>  What are your thoughts on this? What sort of behavior should we be
>> expecting?
>>
>
> Well, RFC 4724 says:
>
>    It is noted that the normal BGP procedures MUST be followed when the
>    TCP session terminates due to the sending or receiving of a BGP
>    NOTIFICATION message.
>
> "Cease" of course being a NOTIFICATION.
>
> This is also relevant:
>
> http://tools.ietf.org/html/**draft-keyupate-idr-bgp-gr-**extension-00<http://tools.ietf.org/html/draft-keyupate-idr-bgp-gr-extension-00>
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