Configuring a Large-Community Filter

A Large-Community filter is used to filter BGP routes based on Large-Community attributes contained in BGP routes. The Large-Community attribute is an extended Community attribute. The Community attribute is a group of destination addresses with the same characteristics and consists of a set of 4-byte values, each of which specifies a community. Generally, the Community attribute on the NetEngine 8000 F is in the format of aa:nn, where aa specifies a 2-byte AS number and nn specifies the Community attribute ID defined by an administrator. The Community attribute is not flexible enough because it fails to carry a 4-byte AS number and contains only one Community attribute ID. To address this problem, the Large-Community attribute can be used instead. The Large-Community attribute consists of a set of 12-byte values and is in the format of Global Administrator:LocalData1:LocalData2.

The Large-Community filter is used to filter only BGP routes because it is a private BGP attribute.