External Community List

About this task

A BGP external community is a group of routes sharing a common attribute, regardless of their network or physical boundary. By using a BGP community attribute, routing policies can implement inbound or outbound route filters based on a community tag, rather than a long list of individual permit or deny rules. A BGP community list is used to create groups of communities to use in a match clause of a route map. An external community list can be used to control which routes are accepted, preferred, distributed, or advertised.

To define a BGP external community list:

Procedure

Select Configuration > Network > BGP > External Community List
Select Add to create a new community list or Edit to modify the attributes of a selected list. Existing lists can be copied or renamed as needed.
Define whether the list is Standard or Expanded.
Standard community lists specify known communities and community numbers. Expanded community lists filter communities using a regular expression that specifies patterns to match the attributes of different communities.

Set the following based on the Standard or Extended option selected:


Community Id	If selecting Standard, enter a numeric community ID unique to this particular rule. If selecting Extended, enter a regular expression unique to this particular rule.
Allow	Use the drop-down menu to Permit or Deny requests for the external community ID. The default setting is deny.

Click OK to save the changes, Reset to revert to the last saved configuration or Exit to close the screen.