第35题: [简答题]what’s the role of community attribute in the bgp route？ 参考答案:
BGP communitiy can be used to as tag of a set of routes. Those tags can be used for applying specific routing policy for a group of routes.
There are four well-known communities：
Internet：all route belongs to this community by default and is advertised freely.
No-export：routes belong to the community cannot be advertised to EBGP peer.
No-advertise：routes belong to the community cannot be advertised to any BGP peer.
Local-as：routes belong to the community cannot be advertised to eBGP peer，or if confederation is used，routes cannot be advertised to conferation eBGP peer and normal eBGP peer.
