Named expanded community-list & regular expressions

[jhalliodc]

I am looking for some insight on why this may not be working.  My platform is a Catalyst 6500, SUP-720, PFC3BXL, MSFC3 running 12.2(33)SXI8.

I have written an expanded named community-list to match a range of communities.

ip community-list expanded SetLocalPref_190 permit 65000:20([0-9][0-9])

This should match 65000:2000 through 65000:2099.

I've built a route-map which is applied outbound to a neighboring iBGP router.  The intention of the route-map and the community-list is to match routes with a community value within the range and set it's local preference to 190 (down from a pre-set default of 200 in my network).

route-map iBGP_OUT permit 10

match community SetLocalPref_190

set local-preference 190

!

route-map iBGP_OUT permit 20

Long story short, this isn't working and the outbound routes are not having their local preference modified when the prefixes in fact have a matching community.

I also tried ip extcommunities with the same result.

[milan.kulik]

Hi,

a) If you issue

sh ip bgp community-list SetLocalPref_190

on your router, are you getting any prefixes listed?

b) You might have forgotten to configure

neighbor ... send-community

towards your iBGP neighbor?

HTH,

Milan

[jhalliodc]

Thank you for taking the time to read and respond to my issue.  Here is what I have conlcuded after receiving your suggestions.

a)  show ip bgp community-list SetLocalPref_190 returns the exact results I would expect and matches all of the prefixes that it should.

b)  my iBGP neighor peer is configured with send-community and does receive these communities.

For what it's worth, I opened a TAC case on this also and their suggestion was to add a plus(+) to the end of the regular expression.  This will match one or more instance, but I/we are not understanding how this will have any effect.

The regular express written either way (with or without the +) returns the expected results when the command "show ip bgp community-list SetLocalPref_190" is issued.

[paul driver]

Do you have any other outbound filter for that peering?

-As the route-map for bgp outbound traffic is at the bottom of the outbound order listing and was wondering if this isnt being proceesed becasue of that?

Outbound bgp order::
Distribute list

Prefix-list

Filter-list

Route-map

res

Paul

[jhalliodc]

Hi Paul, good point but the route-map is the only filtering applied at the moment.  For what it's worth, the iBGP session was first established with a prefix-list applied outbound which filtered all outbound advertisements and then, the route-map was applied and the prefix-list removed.  The session itself has never been cleared except for soft outbound reconfigurations.

[jhalliodc]

I got my answer from Cisco TAC and I should have thought of this.  The iBGP session where the route-map is applied is an RR-Client.  Therefore, modifying the local preference on the outbound advertisements wouldn't be possible for the reflected routes.

I'll modify my the local preference on the receiving end.