3Com 10014299 Configure the Cluster ID, Configure BGP Community, Standard-community-list-number

462 CHAPTER 30: CONFIGURING BGP

Table 542 Configure the Cluster ID

Operation	Command
Configure Cluster-ID of the	reflect cluster-id cluster-id
Route-Reflector
Remove Cluster-ID of the Route-Reflector	undo reflect cluster-id cluster-id

By default, the router ID of the route reflector is used as the cluster ID.

Configuring a BGP In BGP range, a community is a logical area formed by a group of destinations Community which share common attributes for applying the route policy. A community is not

limited to a network or an AS, and has no physical boundary.

The community attribute is an optional and transitional attribute. Some communities are commonly recognized and globally functional. These communities are called standard communities. Sometimes the extended community attribute can be defined for special purposes.

The community attribute list is used to identify the community information. It can be a standard-community-list and an extended-community-list.

In addition, one route can have more than one community attribute. The speaker with multiple community attributes in a route can work according to one, several or all attributes. The community attribute can be added or modified before the router transfers a route to other peers.

Perform the following configurations in system view.

Table 543 Configure BGP Community

Operation	Command
Create a standard-community-list	ip community-list
	standard-community-list-number {
	permit deny } { aa:nn internet
	no-export-subconfed no-advertise
	no-export }
Specify a extended-community-list entry	ip community-list
	extended-community-list-number {
	permit deny } as-regular-expression
Delete the specified community list	undo ip community-list
	{standard-community-list-number
	extended-community-list-number }

By default, no community list is created.

Configuring a BGP AS Confederation is another method to solve the problem of a sudden increase of

Confederation Attribute IBGP closed networks inside an AS. An AS is divided into multiple sub-ASs and the IBGP peers inside the sub-ASs are fully connected, and each sub-AS connects with other sub-ASs inside the confederation. Among the subsystem, the peers perform EBGP sessions, but they can exchange routing information just like IBGP peers. All the important information such as the next hop, MED value and the local priority will not be lost when passing through the AS.