Appreciate any comments.

Have you tried the "no-export" or "no-advertise" community in real world?

Thanks!

I am puzzled why you feel ok to configure all of the EBGP peers with a route map and a prefix list to set the community but do not want to configure the EBGP peer with a prefix list or a distribute list or a route map to prevent advertisement of the provider dependent prefix.

If you try to use the no export or no advertise community you will be advertising the provider dependent prefix to your immediate peers and it seems to me to be a problem if you advertise that prefix to any of the other external peers. So the best solution is some route filtering (distribute list, prefix list, or route map) on the EBGP peers.

HTH

Rick

Hi Rick,

Thanks for your response. I currently have outbound filter-list applied on all my eBGP peerings and I worried too much filtering might affect the performance of the router. Using community might be another alternative idea but considering your comments also with Rick below prefix-list or distribute-list will help.

If say I applied both filter-list and prefix-list on the neighbor statement do you see any issue?

Thanks.

- Richard

In the config all you need is to apply one.

Here is a link that has some basic info http://www.cisco.com/en/US/partner/tech/tk365/technologies_configuration_example09186a008009456d.shtml

Basically you would use one or the other but not both when performing the funciton of filtering.

router bgp 300

network 1.0.0.0

network 2.0.0.0

neighbor 10.10.10.10 remote-as 100

neighbor 10.10.10.10 route-map localonly out

neighbor 10.10.10.10  prefix-list  ABC in

neighbor 20.20.20.20 remote-as 200

neighbor 20.20.20.20 route-map ROUTE-ADV out

neighbor 20.20.20.20 prefix-list  ABC in

ip prefix-list  ABC  seq 5 permit 0.0.0.0/0

ip prefix-list localonly seq 5 10.10.10.0/24 le 32

ip prefix-list ROUTE-ADV seq 5 permit 10.0.0.0/24 le 32

ip prefix-list ROUTE-ADV seq 10 permit 10.1.0.0/24 le 32

route-map ROUTE-ADV permit 10

match ip address ROUTE-ADV

set ip local-preference 200

route-map localonly permit 10

match ip address localonly

This is a sample config taken off the cisco link provided but also a few additions so you can see the differences and how they are applied.

Richard

No I do not see any issues if you use both a prefix list and a filter list on a neighbor statement.

HTH

Rick