Configuring A Bgp Community - 3Com 3032 Configuration Manual

462 C 30: C
HAPTER ONFIGURING
Configuring a BGP
Community
Configuring a BGP AS
Confederation Attribute
BGP
Table 542 Configure the Cluster ID
Operation
Configure Cluster-ID of the
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.
In BGP range, a community is a logical area formed by a group of destinations
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
Create a standard-community-list
Specify a extended-community-list entry
Delete the specified community list
By default, no community list is created.
Confederation is another method to solve the problem of a sudden increase of
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.
Command
reflect cluster-id cluster-id
Command
ip community-list
standard-community-list-number {
permit | deny } { aa:nn | internet |
no-export-subconfed | no-advertise |
no-export }
ip community-list
extended-community-list-number {
permit | deny } as-regular-expression
undo ip community-list
{standard-community-list-number |
extended-community-list-number }