On Thu, 15 May 2003, Mark Radabaugh wrote:
I'm having a hard time finding best practices for filtering outbound bgp announcements when providing transit to bgp-speaking customers. While we currently multi-home to several providers it appears we will soon need to provide transit for customers with their own AS's.
I like using BGP communities: o filter announcements you receive from downstreams based on your criteria of choice o set a specific BGP community (yourAS:whatever) on announcements which are to be propagated to various places (upstream providers, etc.) o do output filtering based on the communities you set Make sure you clear yourAS:whatever in announcements from your BGP peers. You can use this same technique for prefixes you originate, so that all your outbound BGP filtering is based on communities. ________________________________________________________________________ Jay Ford, Network Engineering Group, Information Technology Services University of Iowa, Iowa City, IA 52242 email: jay-ford@uiowa.edu, phone: 319-335-5555, fax: 319-335-2951