North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Regular Expressions ......

  • From: Ally Gudgeon
  • Date: Fri May 26 05:18:36 2000

Hi All,

I am having a few problems getting my BGP filtering to work - and am
experiencing some strange results..

I have two routers connected to a peering point, we have decided that we
want to set local preferences of

110 to 1-deep AS-paths (as-path ACL 1)
100 to 2-deep AS-paths (as-path ACL 2)
and 90 to 3-deep AS-paths (as-path ACL 3)
and to not accept 4-deep AS-paths (as-path ACL 4)

I have the following as-path ACLs to try to set that and am using route
maps.

ip as-path access-list 1 permit ^[0-9]*$
ip as-path access-list 2 permit ^[0-9]*_[0-9]*$
ip as-path access-list 3 permit ^[0-9]*_[0-9]*_[0-9]*$
ip as-path access-list 4 permit .*

This appears to have failed miserably....It is not setting local prefs
correctly if they are 3-deep and have a repetition of an AS number it sees
it as 4-deep
If they are 4 AS's deep it doesn't apply a local preference but if it knows
it from our other core router it sets a local pref of 100 but prefers the
direct route?

(ALSO: If I do a sh ip bgp reg ^[0-9]*_[0-9]*$ it lists both 1-deep and
2-deep AS's....surely it should just list 2-deep?)

Any help would be greatly appreciated!......

Thanks in advance..


Ally


email - [email protected]
++++++++++++++++++++++++++++++++++++++++++++++++++++++++
This email and any files transmitted with it are confidential and intended
solely for the use of the individual or entity to whom they are addressed.
The views expressed in the email and files transmitted with it are those of
the individual, not the company. If you have received this email in error
please notify [email protected]
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++