11.9.3 BGP Community in Route Map

In Route Map (see Route Map), we can match or set BGP communities attribute. Using this feature network operator can implement their network policy based on BGP communities attribute.

Following commands can be used in Route Map.

Route Map: match community word

Route Map: match community word exact-match

This command perform match to BGP updates using community list word. When the one of BGP communities value match to the one of communities value in community list, it is match. When exact-match keyword is spcified, match happen only when BGP updates have completely same communities value specified in the community list.

Route Map: set community none

Route Map: set community community

Route Map: set community community additive

This command manipulate communities value in BGP updates. When none is specified as communities value, it removes entire communities attribute from BGP updates. When community is not none, specified communities value is set to BGP updates. If BGP updates already has BGP communities value, the existing BGP communities value is replaced with specified community value. When additive keyword is specified, community is appended to the existing communities value.

Route Map: set comm-list word delete

This command remove communities value from BGP communities attribute. The word is community list name. When BGP route’s communities value matches to the community list word, the communities value is removed. When all of communities value is removed eventually, the BGP update’s communities attribute is completely removed.