BGP AS-Path Question???

[mdargin]

We have a configuration in our router that look like this:

router bgp 6544

Neighbor 2.3.3.3 filter-list 1 out

!

ip as-path access-list 1 permit ^$

What does the ^$ mean? Does it mean that any Autonomous system can advertise outbound of the router. If it means that what is the purpose of the statemnt?

Thank You for any responses

[Richard Burts]

Mark

The ^$ means to only allow advertisement for routes that originate within your AS. Technically it tests for routes with an empty AS path and the only routes that have an empty AS path are the routes that originate within your own AS.

This test is a good way to assure that you do not become a transit AS. It is a good thing to do.

HTH

Rick