You can group destinations into communities to simplify policy administration. A community is a group of destinations that share a common administrative property.
Use community control routing policies with respect to destinations. Create communities when you have more than one destination and want to share a common attribute.
The following list identifies specific community types:
Internet—advertise this route to the Internet community
no advertise—do not advertise to BGP peers including iBGP peers
You can use a community to control which routing information to accept, prefer, or distribute to other BGP neighbors. If you specify the append option in the route policy, the router adds the specified community value to the existing value of the community attribute. Otherwise, the specified community value replaces a previous community value.