Did your BGP crash today?

Pierre Francois pierre.francois at uclouvain.be
Mon Aug 30 04:21:42 CDT 2010


Thomas,

Wouldn't the confusion come from the fact that updates are considered as 
keepalives, so that Claudio sees so few type 4 messages because he receives 
updates ?

Sec 4.2, Hold Time :

"The calculated value indicates the maximum number of
seconds that may elapse between the receipt of successive
KEEPALIVE and/or UPDATE messages from the sender."

Regards,

Pierre.

Thomas Mangin wrote:
>> Apart from one big vendor most BGP speaker only send KEEPALIVES when they
>> need to. So on my full feeds I see sessions running for more then 1 month
>> which received less then 300 KEEPALIVE packets. 
> 
> 
> The negociaged holdtime is always the lower value presented between two routers. The default HoldTime timer for Cisco is 180 seconds and for Juniper 90.
> So you should see a KEEPALIVE packet every minute from/to Cisco routers, and one every 30 seconds between Junipers.
> 
> Should a BGP speaker do not see any KEEPALIVE during $HOLDTIME, it will tear the session down.
> You are telling me that your effective holdtime is 2592000 seconds when the HOLDTIME field is 16 bits ... hum ...
> http://www.faqs.org/rfcs/rfc4271.html section 4.2
> 
> So unless you know something I don't, I believe you are totally mistaken :)
> 
> Thomas
> 
> 
> 





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