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BGP community format

Hi there,

The ip bgp-community new-format is documented as a local display command to change the 32-bit format in AA:NN format (4 bytes), in addition the documentation indicates this command has no effect in the community exchange; however, I have experienced problems (routes not learned) in a PE router, when the CPE router has not included the ip bgp-community new-format and all advertised routes has attached the community in 32-bit format. Is this command mandatory in both PE and CPE routers?

Thanks in advance


Re: BGP community format


This command should have no effect on the actual community exchange. What specific problem did you have ?


Cisco Employee

Re: BGP community format

This would be normal behavior if you make use of an expanded community-list on the receiving router to permit or deny the incoming prefixes.

The expanded community-list allows you to compare a community using a regular expression. This regular expression might or might not match depending if the command "ip bgp-community new-format" is configured or not.

If an expanded community-list is used with the format , make sure that "ip bgp-community new-format" is configured. Otherwise it won't match.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
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