Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements
Webcast-Catalyst9k
New Member

Filtering Routes on BGP

My ASN 65002. I want to filtering inbound traffic at my border router. Say I have to links. Link "A" connects to private IXP (ASN 65003) and link "B" connects to global Internet. I just want to filter so only some network from another AS 65001 (which is also have same connection as I have) can trough my "A" link and another network routes trough link "B".

2 REPLIES

Re: Filtering Routes on BGP

Hi Maurice,

you cannot force the traffic decisions of another autonomous system.

you can only try to influence their decisions by manipulating the policies.

There are 2 ways to do this 1) MED and 2) AS-path prepending

you can use MED to influence the routing decisions to your AS but this has very limited reach. It can be used only to influence routing decisions to the directly conencted AS as thsi attiribute does not pass along to other AS. Also the other side AS should be using the always-compare-med command.

Another preferred way is to use AS-path prepending. you can use this attribute and advertise your subnets in such a way that some netwoeks seems to be preferable via one route and rest via other.

HTH

Narayan

New Member

Re: Filtering Routes on BGP

Hi,

You can use prefix list with neighbor command in bgp config to selectively permit+deny specific routes to learn and advertise..

Thx,

G

104
Views
0
Helpful
2
Replies
CreatePlease to create content