32-52
Cisco ME 3400 EthernetAccess Switch SoftwareConfiguration Guide
78-17058-01
Chapter32 Configuring IP Unicast Routing
Configuring BGP
Beginning in privileged EXEC mode, follow these steps to create and to apply a community list:
Configuring BGP Neighbors and Peer Groups
Often many BGP neighbors are configured with the same update poli cies ( t hat is, the same o utbou nd
route maps, distribute lists, filter lists, update source, and so on). Neighbors with the same update
policies can be grouped into peer groups to simplify configuration and to make updating more efficient.
When you have configured many peers, we recommend this approach.
To configure a BGP peer group, you create the peer group, assign options to the peer group , a nd add
neighbors as peer group members. You configure the peer group by using the neighbor router
configuration commands. By default, peer group members inherit all the configu ratio n o pti ons of the
peer group, including the remote-as (if configured), version, up dat e-sour ce , out- rou te- map,
out-filter-list, out-dist-list, minimum-advertisement-interval, and next-hop -self. All peer group members
also inherit changes made to the peer group. Members can also be configured to override the options that
do not affect outbound updates.
To assign configuration options to an individual neighbor, specify any of these router configuration
commands by using the neighbor IP address. To assign the options to a peer group, specify any of the
commands by using the peer group name. You can disable a BGP peer or peer group without removing
all the configuration information by using the neighbor shutdown router configuration command.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 ip community-list community-list-number
{permit | deny} community-number Create a community list, and assign it a number.
•The community-list-number is an integer from 1 to 99 that
identifies one or more permit or deny groups of communities.
•The community-number is the number configured by a set
community route-map configuration command.
Step3 router bgp autonomous-system Enter BGP router configuration mode.
Step4 neighbor {ip-address | peer-group name}
send-community Specify that the COMMUNITIES attribute be sent to the neighbor at
this IP address.
Step5 set comm-list list-num delete (Optional) Remove communities from the community attribute of an
inbound or outbound update that match a standard or extende d
community list specified by a route map.
Step6 exit Return to global configuration mode.
Step7 ip bgp-community new-format (Optional) Display and parse BGP communities in the format AA:NN.
A BGP community is displayed in a two-part format 2 bytes long. Th e
Cisco default community format is in the format NNAA. In the most
recent RFC for BGP, a community takes the form AA:NN, where the
first part is the AS number and the second part is a 2-byte number.
Step8 end Return to privileged EXEC mode.
Step9 show ip bgp community Verify the configuration.
Step10 copy running-config startup-config (Optional) Save your entries in the configuration file.