Plz give me brief explanation about community attribute in bgp ? How it is used & why it is used ?
Post-It Notes. It just carries a note about a route. Some communities (internet, no-export, local-as, no-advertise) have preset values and functions, which I believe you'll find in the web page Conwyn provided....
Otherwise, using a numerical value has no set meaning unless you have a policy to match and do something with it!