Configuring a Community Filter
Context
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 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.
Procedure
- Run system-view
The system view is displayed.
- Run ip community-filter
A community filter is configured.
To configure a basic community filter, run the ip community-filter { basic comm-filter-name | basic-comm-filter-num } [ index index-number ] { 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 } [ index index-number ] { permit | deny } regular-expression command.
In the preceding command, regular-expression indicates that the community filter uses a regular expression to define matching rules. For details about regular expressions, see "Overview of CLIs" in CloudEngine 12800 and 12800E Series Switches- Configuration Guide - Basic Configuration.
- Run commit
The configuration is committed.