[j-nsp] export policy Junos 9.0

[Richard A Steenbergen]

On Fri, Oct 24, 2008 at 08:43:26AM +0200, david.roy at orange-ftgroup.com wrote:
> 
> Thank you,
>  
> I've opened a Case and I had the same response : normal behavior. 

Juniper's BGP implementation is heavily built around the concept of
"update groups". This optimization helps reduce CPU load in the common
case where there are many BGP neighbors sharing the same export policy,
by performing the policy evaluation only once then replicating the 
results to all of the individual neighbors in the group. You can see 
your BGP grouping on your router with the command "show bgp group".

Unfortunately, when you change your export policy it changes your export
"group" and causes Juniper to bounce the session. There is nothing
inherient about this process which requires you to bounce the session
(like most of the other causes for bouncing, which require a new session
to be negotiated), it's just that Juniper never fixed their BGP
implementation to handle a dynamic export group change. Thus it is
"normal for them".

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)