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BGP community announcement?

Posted on 2011-09-29
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Hi,

Realizing that I'm way out of my comfort zone, I had our bandwidth carrier do some troubleshooting for a possible network related issue to and from one of our managed server providers. Having done the troubleshooting end-to-end I wanted to make sure that there isn't any silliness on the BGP routes, etc.

Here is what the network person Above.net mentioned:
" We can have you apply the community 6461:5550  to your route announcements to us for the  209.*.*.*/24 block" ... "The other community that we could use is 6461:5000, which suppress the route to all peers, but I would suggest doing it to just L3 to start."

That being said, on the 6509, do I need to update the appropriate route-map to accomplish this?

Let me know if you need more details.
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Question by:wsani
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Garry Glendown earned 2000 total points
ID: 36817228
Yes, setting a BGP community for a prefix works like this (at least on IOS routers, 6500 should be similar):

- set a route-map to a BGP neighbor entry, e.g. "neighbox x.x.x.x route-map myRouteMap"
- on the route-map, do your matching, then set the community for the prefix:

route-map myRouteMap permit 10
  match ip address prefix-list PrefixListToBeTagged
  set community 6461:5500 additive

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Instead of the prefix list, you could also use an access list ... that's about all you need to add the community ... then do a "clear ip bgp NEIGHBOR-IP out" to update the outgoing prefixex to your uplink ...
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