Administrator Guide

{deny | permit} as-regular-expression
3. Return to CONFIGURATION mode.
AS-PATH ACL
exit
4. Enter ROUTER BGP mode.
CONFIGURATION mode
router bgp as-number
5. Filter routes based on the criteria in the configured route map.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group-name} filter-list as-path-name {in | out}
Configure the following parameters:
● ip-address or peer-group-name: enter the neighbor’s IP address or the peer group’s name.
● as-path-name: enter the name of a configured AS-PATH ACL.
● in: apply the AS-PATH ACL map to inbound routes.
● out: apply the AS-PATH ACL to outbound routes.
To view which commands are configured, use the show config command in CONFIGURATION ROUTER BGP mode and the
show ip as-path-access-list command in EXEC Privilege mode.
To forward all routes not meeting the AS-PATH ACL criteria, include the permit .* filter in your AS-PATH ACL.
Configuring BGP Route Reflectors
BGP route reflectors are intended for ASs with a large mesh; they reduce the amount of BGP control traffic.
NOTE: Dell Networking recommends not using multipath and add path simultaneously in a route reflector.
With route reflection configured properly, IBGP routers are not fully meshed within a cluster but all receive routing information.
Configure clusters of routers where one router is a concentration router and the others are clients who receive their updates
from the concentration router.
To configure a route reflector, use the following commands.
● Assign an ID to a router reflector cluster.
CONFIG-ROUTER-BGP mode
bgp cluster-id cluster-id
You can have multiple clusters in an AS.
● Configure the local router as a route reflector and the neighbor or peer group identified is the route reflector client.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group-name} route-reflector-client
When you enable a route reflector, the system automatically enables route reflection to all clients. To disable route reflection
between all clients in this reflector, use the no bgp client-to-client reflection command in CONFIGURATION
ROUTER BGP mode. All clients must be fully meshed before you disable route reflection.
To view a route reflector configuration, use the show config command in CONFIGURATION ROUTER BGP mode or the
show running-config bgp in EXEC Privilege mode.
Aggregating Routes
The system provides multiple ways to aggregate routes in the BGP routing table. At least one specific route of the aggregate
must be in the routing table for the configured aggregate to become active.
To aggregate routes, use the following command.
AS_SET includes AS_PATH and community information from the routes included in the aggregated route.
● Assign the IP address and mask of the prefix to be aggregated.
CONFIG-ROUTER-BGP mode
Border Gateway Protocol IPv4 (BGPv4)
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