Reference Guide

connected to the router. The BGP process rst determines if all internal BGP peers are reachable, then it determines which peers outside
the AS are reachable.
1 Assign an AS number, and enter ROUTER-BGP mode from CONFIGURATION mode (1 to 65535 for 2-byte, 1 to 4294967295 for 4-
byte). Only one AS number is supported per system. If you enter a 4-byte AS number, 4-byte AS support is enabled automatically.
router bgp as-number
2 Enter a neighbor in ROUTER-BGP mode.
neighbor ip-address
3 Add a remote AS in ROUTER-NEIGHBOR mode, from 1 to 65535 for 2-byte or 1 to 4294967295 for 4-byte.
remote-as as-number
4 Enable the BGP neighbor in ROUTER-NEIGHBOR mode.
no shutdown
To reset the conguration when you change the conguration of a BGP neighbor, use the clear ip bgp * command. To view the BGP
status, use the show ip bgp summary command.
View BGP summary with 2-byte AS number
OS10# show ip bgp summary
BGP router identifier 202.236.164.86 local AS number 64901
Neighbor AS MsgRcvd MsgSent Up/Down State/Pfx
120.10.1.1 64701 664 662 04:47:52 established 12000
View BGP summary with 4-byte AS number
OS10# show ip bgp summary
BGP router identifier 11.1.1.1, local AS number 4294967295
BGP local RIB : Routes to be Added 0, Replaced 0, Withdrawn 0
1 neighbor(s) using 8192 bytes of memory
Neighbor AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/Pfx
5.1.1.2 4294967295 0 0 0 0 0 00:00:00 Active
For the router ID, the system selects the rst congured IP address or a random number. To view the status of BGP neighbors, use the
show ip bgp neighbors command. For BGP neighbor conguration information, use the show running-config bgp command.
The example shows two neighbors — one is an external BGP neighbor, and the other is an internal BGP neighbor. The rst line of the
output for each neighbor displays the AS number and states if the link is external or internal.
The third line of the show ip bgp neighbors output contains the BGP state. If anything other than established displays, the neighbor
is not exchanging information and routes - see IPv6 commands for more information.
View BGP neighbors
OS10# show ip bgp neighbors
BGP neighbor is 5.1.1.1, remote AS 1, internal link
BGP version 4, remote router ID 6.1.1.1
BGP state established, in this state for 00:03:11
Last read 01:08:40 seconds, hold time is 180, keepalive interval is 60 seconds
Received 11 messages
3 opens, 1 notifications, 3 updates
4 keepalives, 0 route refresh requests
Sent 14 messages
3 opens, 1 notifications, 0 updates
10 keepalives, 0 route refresh requests
Minimum time between advertisement runs is seconds
Capabilities received from neighbor for IPv4 Unicast:
MULTIPROTO_EXT(1)ROUTE_REFRESH(2)CISCO_ROUTE_REFRESH(128)
Capabilities advertised to neighbor for IPv4 Unicast:
MULTIPROTO_EXT(1)ROUTE_REFRESH(2)CISCO_ROUTE_REFRESH(128)
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Layer 3