BGP Path Filtering
mark at amplex.net
Fri May 16 02:29:18 UTC 2003
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 find lots of references (and understand) the basic
ip as-path access-list 3 permit ^$
and it would seem that should we wish to provide transit for a bgp customer
AS12345 we would use:
ip as-path access-list 3 permit ^12345$
but I think this breaks if AS12345 prepends their advertisement.
Next up is:
ip as-path access-list 3 permit ^12345_[0-9]$*
Which seems correct to me. Is this still best practice (or even correct)?
More information about the NANOG