The community attribute identifies routes with the same characteristics without considering IP prefixes and AS numbers. Configuring community filters and community attributes simplifies route management when it is inconvenient to use the IP prefix list or AS_Path filter. For example, a company branch needs to receive routes only from its headquarters and from branches in adjacent countries. In this case, you can configure different community attributes for each of the branches. Routes in the original branch can then be managed based on community attributes, without considering IP prefixes and AS numbers of routes in different countries.
Community filters are classified into basic and advanced community filters. An advanced community filter supports regular expressions and is more flexible than a basic community filter.
The system view is displayed.
A community filter is configured.
To configure a basic community filter, run the ip community-filter { basic comm-filter-name | basic-comm-filter-num } { permit | deny } [ community-number | aa:nn | internet | no-export-subconfed | no-advertise | no-export ] &<1-20> command.
To configure an advanced community filter, run the ip community-filter { advanced comm-filter-name | adv-comm-filter-num } { permit | deny } regular-expression command.
In the preceding command, regular-expression indicates that the community filter uses a regular expression to define matching rules.