Two Peering on BGP - How to Block Prefix

[jimmy20.bpl]

Hi, 

We have a single Internet link from ISP configured with eBGP.  Only one pool is advertised under BGP 10.20.30.0/24

Additionally, recently we have configured one more eBGP peering on same router with our vendor (who is on Internet).

Requirement is to block advertising 10.20.30.0/24 pool to ISP, so that same can be learned / advertised from Vendor AS.  (Incoming from internet should be from vendor AS path and outgoing should to through ISP peering only).

I have applied AS path prepend but same is not effectively working. Any suggestion to get the same done with some other process, I guess with Prefix list. 

please advise.

Rgds

[Mark Malone]

Hi

Yes you could use a route-map attached to the neighbour  statement with prefix-list setup or just a prefix direct off the neighbour

router bgp xxx

neighbor 10.1.200.12 route-map as3498-outgoing-policy out

route-map as3498-outgoing-policy permit 10
 match ip address prefix-list TESTNET

ip prefix-list TESTNET seq 1 deny x.x.x.x/x

or direct

 neighbor 10.1.200.18 prefix-list LOCALROUTES out

or

use a distribute-list with standard acl

http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13750-22.html

http://www.cisco.com/c/en/us/td/docs/ios/12_2s/feature/guide/fsbgporf.html#wp1027188