[afnog] Private IP Filters in bgp

[Mark Tinka]

On Friday, May 25, 2012 04:21:42 PM Shake Righa wrote:

> Yasini,
> 
> You could try and instead of using prefixes for the
> filters only make the use of a route-map.This would add
> more felxibility such as adding of local-pref or
> communities to the incoming routes.

There are situations where prefix lists alone can be useful, 
e.g., if you don't want to accept any routes from a peer, or 
if you want to accept only the default route with no special 
BGP attributes attached, e.t.c.

Route maps are more complex than prefix lists, and 
rightfully so because they are more powerful.

However, as in your sample configuration to Yasini, they can 
also be combined in order to refine the routing policy.

Of course, this whole concept holds true for IOS and IOS XE. 
The way routing policies are implemented in IOS XR and Junos 
is massively different, and in all likelihood, would need to 
implement the equivalent of a route-map just to do something 
a prefix list alone could have. So be mindful of that, 
particularly if you want to harmonize configuration language 
in a multi-vendor, multi-OS network.

Cheers,

Mark.