Extended Community Lists

An extended community is a larger group of destinations that share some common attribute. The BGP extended community list has attributes that can be used to mark a set of prefixes that share a common attribute. These markers are used in the match clause of a route map to filter the routes for implementing route leaks among virtual routers. You can also define policy list objects with the extended community list for filtering. The extended community list is an ordered list of matching statements. Routes are matched against the rules until a match is found with the specified route target (standard) or regular expression (expanded). Use the Extended Community page to create and edit extended community list policy objects.

Note	The extended community lists are applicable only for configuring import or export of routes.

You can use this object with FTD devices.

Procedure

Step 1

Select Objects > Object Management and choose Community List > Extended Community from the table of contents.

Step 2

Click Add Extended Community List.

Step 3

In the Name field, specify a name for the extended community list object. The length of the name cannot exceed 80 characters.

Step 4

Select the extended community rule type:

Click the Standard radio button to specify one or more route targets.
Click the Expanded radio button to specify regular expressions.

Note	You cannot have entries using Standard and Expanded extended community rule type in the same Extended Community List object.

Step 5

Click Add.

Step 6

If you have selected Standard as the extended community rule type, specify the following:

In the Sequence No field, enter the order in which you want the rule to be executed.

The sequence number must be unique in the list.
From the Action drop-down list, if you want to permit routes that have matching route target that is specified here, select Allow; if you want to deny routes that have matching route target that is specified here, select Block.
In the Route Target field, specify a route target.
- You can add a single route target or a set of route targets separated by commas in a single entry. For example, 1:2,1:4,1:6.
- Valid values can be from 1:1 to 65534:65535.
- You can have a maximum of 8 route targets in an entry.
- You cannot have redundant route target set across multiple entries. For example, say you want to configure seq1 with 1:200,100:100,1:300 route targets, and seq2 with 1:300,100:100,1:200 route targets. This results in redundant route target set and cannot be deployed.

Step 7

If you have selected Expanded as the extended community rule type, specify the following:

In the Sequence No field, enter the order in which you want the rule to be executed.

The sequence number must be unique in the list.
From the Action drop-down list, if you want to permit routes that have matching regular expression that is specified here, select Allow; if you want to deny routes that have matching regular expression that is specified here, select Block.
Specify the regular expression in the Expressions field.
- You can add a single route target or a set of route targets separated by a space in a single entry. For example, ^((16) | (18)):(.)$.
- You can add a maximum of 16 regular expressions to an entry.
- You cannot have redundant regular expression set across multiple entries. For example, say you want to configure seq1 with ^((16) | (18)):(.)$ ^4_[0-9]*$ route targets, and seq2 with ^4_[0-9]*$ ^((16) | (18)):(.)$ route targets. This results in redundant regular expression set and cannot be deployed.
For details on BGP regular expressions, see here.

Step 8

If you want to allow overrides for this object, check the Allow Overrides check box; see Allowing Object Overrides.

Step 9

Click Save.

The extended community list can be referenced in the match clause of the Route Map object or Policy List object:

In the Route Map object, the name of the extended community list is displayed in the Add Route Map Entry > Match Clause > BGP > Community List > Add Extended Community List dialog. For more details on configuring BGP settings in a route map, see Route Maps.
In the Policy List object, the name of the extended community list is displayed in the Add Policy List > Community Rule > Add Extended Community List dialog. For more details on configuring BGP settings in a policy list, see Policy Lists.