05-16-2012 02:40 AM - edited 03-04-2019 04:22 PM
Hi All,
Please see attached topology,
Router AS 200 have ebgp peering with AS 100 and also with AS2( which has direct peering with AS1) .We sending all the routes from AS200 to AS 100, but now
We have requirments at router in AS 200 that it only send route to AS 100 from AS2 and filter all the routes comming from AS1.
I am thinking to use AS filter at AS 200 towards AS100 with regular expration, but not sure which one will serve this requirment.
Thanks and Regards,
05-16-2012 03:45 AM
Hi
a ) If the requiremnet is to advertise to 100 ONLY AS 2 :
ip as-path access-list 100 permit _2$
Permit AS2 , deny anything
b ) If you have also other prefixes , but you want only to filter AS 1:
ip as-path access-list 100 deny _1$
ip as-path access-list 100 permit .*
Deny AS1, permit anything
Either way apply the as-path acl on OUT to AS100.
router bgp 200
neigh AS-100-NEI filter-list 100 out
Dan
05-16-2012 04:27 AM
Thanks DAN,
AS 200 is also connected to lots of other AS's, and I need all thses router goes from AS 200 to AS100,but only want to drop routes from AS1.
Regards,
05-16-2012 04:42 AM
Hi,
so Dan's option B is what you need.
Regards.
Alain
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