Chuck,

You need to make the deny '^5555 .*'.  Assuming you are putting this on an
EBGP router peering with AS5555.

"ip as-path access-list 55 deny ^5555 .*"

The '^' is an anchor in regex and forces a match at the beginning of the
input string you are comparing.  IE:  Whatever is after the '^' must start
at the beginning of the string being compared to match and make the
epxression true.

To see if you are getting anything from AS5555 try:

"show ip bgp regexp ^5555 .*"

Good way to test your regexp as well.


-Julian

""Chuck Larrieu""  wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> for an as-path filter, here is what I want to accomplish:
>
> from one particular router to another particular router I want to filter
any
> AS path whose most recent AS was 5555
>
> so if the BGP route has a path in the BGP table as 5555 1111 4444 ? or
5555
> 9999 ? etc
> then I want that route to be filtered to a particular neighbor
>
> routes such as 3333 5555 ? or 7777 2222 5555 3333, for example are OK to
> pass
>
> my access-list is:
>
> ip as-path access-list 55 deny ^5555_
> ip as-path access-list 55 permit .*
> !
> and my neighbor statement is neighbor a.b.c.d filter-list 55 out
>
> does the ^ character really mean what I think it is supposed to mean? I.e
> does it filter any AS path that BEGINS with 5555, or is it doing something
> unexpected?
>
> I have a complex mesh ( mess too ;-> ) of BGP neighbors, and it is a bit
> hard to tell if I am accomplishing what I think I am accomplishing.
>
> thanks.
>
> Chuck




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