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Catalyst 3750 MetroSwitch Software Configuration Guide
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Chapter 28 Configuring IP Unicast Routing
Configuring BGP
To configure a BGP peer group, you create the peer group, assign options to the peer group, and 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 configuration options of the
peer group, including the remote-as (if configured), version, update-source, out-route-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.
Beginning in privileged EXEC mode, use these commands to configure BGP peers:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
router bgp autonomous-system Enter BGP router configuration mode.
Step 3
neighbor peer-group-name peer-group Create a BGP peer group.
Step 4
neighbor ip-address peer-group
peer-group-name
Make a BGP neighbor a member of the peer group.
Step 5
neighbor {ip-address | peer-group-name}
remote-as number
Specify a BGP neighbor. If a peer group is not configured with a
remote-as number, use this command to create peer groups
containing EBGP neighbors. The range is 1 to 65535.
Step 6
neighbor {ip-address | peer-group-name}
description text
(Optional) Associate a description with a neighbor.
Step 7
neighbor {ip-address | peer-group-name}
default-originate [route-map map-name]
(Optional) Allow a BGP speaker (the local router) to send the
default route 0.0.0.0 to a neighbor for use as a default route.
Step 8
neighbor {ip-address | peer-group-name}
send-community
(Optional) Specify that the COMMUNITIES attribute be sent to
the neighbor at this IP address.
Step 9
neighbor {ip-address | peer-group-name}
update-source interface
(Optional) Allow internal BGP sessions to use any operational
interface for TCP connections.
Step 10
neighbor {ip-address | peer-group-name}
ebgp-multihop
(Optional) Allow BGP sessions, even when the neighbor is not
on a directly connected segment. The multihop session is not
established if the only route to the multihop peer’s address is the
default route (0.0.0.0).
Step 11
neighbor {ip-address | peer-group-name}
local-as number
(Optional) Specify an AS number to use as the local AS. The
range is 1 to 65535.
Step 12
neighbor {ip-address | peer-group-name}
advertisement-interval seconds
(Optional) Set the minimum interval between sending BGP
routing updates.
Step 13
neighbor {ip-address | peer-group-name}
maximum-prefix maximum [threshold]
(Optional) Control how many prefixes can be received from a
neighbor. The range is 1 to 4294967295. The threshold
(optional) is the percentage of maximum at which a warning
message is generated. The default is 75 percent.
Step 14
neighbor {ip-address | peer-group-name}
next-hop-self
(Optional) Disable next-hop processing on the BGP updates to a
neighbor.
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