The community attribute is used to simplify route-policy management.
The community attribute is used to simplify the application, maintenance, and management of route-policies. With the community attribute used, a group of BGP4+ peers in multiple ASs can share a route-policy. Before advertising a route carrying a community attribute to peers, a BGP4+ device can be configured to change the original community attribute of this route. Community attributes are route attributes, which are transmitted between BGP4+ peers, and the transmission is not restricted within an AS.