Overview

Display all routes with any AS path:

show ip bgp “.*”

Display all routes having at least two AS numbers in the AS path:

show ip bgp “. .+

Display all routes that traversed AS number 600:

show ip bgp “.* 600 .*”

Display all routes with beginning with AS number 300 and ending with AS number 800 in the AS path:

show ip bgp “^300 .* 800$”

Peer Groups

A BGP peer group is a set of BGP neighbors sharing update policies. Rather than define similar policies for each individual neighbor, you can define a peer group and assign policies to the peer group itself. If you modify options for the peer group, all members of the peer group inherit the changes. You can also configure individual members to override those options that do not effect outbound updates.

Peer-groups are comprised of either IBGP or EBGP members. IBGP group members must be in the same AS as the peer-group, which itself must be in the same AS as the router. On the other hand, when you create an EBGP peer-group, an AS number is not associated with the peer-group and all peer-group members must belong to an AS other than the AS set for the router.

Do not mix IBGP and EBGP members in the same peer-group. Members of an EBGP group can be from different ASs. A peer can belong to a single peer-group only.

A BGP peer group is configured by:

Creating the peer group

Assigning Options

Adding neighbors

A BGP peer or peer group can be disabled without deleting all settings with the neighbor shutdown command.

Creating a Peer Group

Create a BGP peer group and add a neighbor to it with the neighbor peer-groupcommand.

Assigning Peer Group Options

A peer group is set with neighbor commands. Peer group members inherit all group options as well as subsequent changes by default. They can also be configured to override those options not pertinent to outbound updates.

Members of a peer group always inherit these attributes: remote-as(if configured), update- source, neighbor filter-list, advertisement-interval, and next-hop-self.

You can set options for an particular neighbor by using any of the following commands with an IP address. If you want to configure options for a peer group, configure any of the commands employing the peer group name.

• Configure a BGP neighbor: neighbor remote-as number

6-14 Configuring the Border Gateway Protocol

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Enterasys Networks X-PeditionTM manual Peer Groups, Creating a Peer Group, Assigning Peer Group Options