User's Manual

Table Of Contents
460
Users Manual of CS-6306R
Perform the following operations to configure the community-attributebased routing information filtration:
Command Purpose
ip community-list standard |
expendedcommunity-list-name
{permit | deny} communtiy-expression
Defines the community list.
route-map map-name
sequence-number {deny | permit}
Configures the route map.
match community-list-name
Configures the matching regulations.
router bgpautonomous-system
Enters the router configuration mode.
neighbor {ip-address }
route-maproute-map-name {in | out }
Applies the route map.
Refer to the section “Example for Route Map Through BGP Community Attribute”.
45.4.2.2.4 Configuring Autonomous System Alliance
The method to reduce IBGP connections is to divide one AS into multiple sub ASs and classify them into an
autonomous system alliance. As to the outside, the alliance seems like an AS. As to the inside of the alliance,
each sub AS is full-connected and connects other sub ASs in the same alliance. Even if the EBGP session
exists in the peers of different sub AS, they still exchange route choice information as IBGP peers do. That is,
they save the next hop, MED and local priority information.
To configure a BGP autonomous system alliance, you must designate the alliance identifier. The alliance
identifier is an AS number. As to the outside, the AS looks like a single AS which takes the alliance identifier
as the AS number.
Run the following command to configure the identifier of the autonomous system alliance:
Command Purpose
bgp confederation0 identifier
autonomous-system
Configures the identifier of the
autonomous system alliance.
Run the following command to designate the autonomous system number belonging to the autonomous
system alliance:
Command Purpose
bgp confederation peers
autonomous-system
[autonomous-system ...]
Designates the AS belonging to the
autonomous system alliance.
Refer to the section “BGP Autonomous System Alliance Example”.
45.4.2.2.5 Configuring Route Reflector
Another method to reduce IBGP connections is to configure the route reflector.
The peers in the route reflector are divided into two groups: client peers and other routers in the AS
(non-client peers). The route reflector reflects the routes between the two groups. The route reflector and the