Administrator Guide

You must use Configuring Peer Groups before assigning them a remote AS.
3 Enable the BGP neighbor.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group-name} no shutdown
Example of the show ip bgp summary Command (2-Byte AS number displayed)
Example of the show ip bgp summary Command (4-Byte AS number displayed)
Example of the show ip bgp neighbors Command
Example of Verifying BGP Configuration
NOTE: When you change the configuration of a BGP neighbor, always reset it by entering the clear ip
bgp command in EXEC Privilege mode.
To view the BGP configuration, enter show config in CONFIGURATION ROUTER BGP mode. To view the
BGP status, use the
show ip bgp summary command in EXEC Privilege mode. The first example shows the
summary with a 2-byte AS number displayed (in bold); the second example shows that the summary with a 4-
byte AS number using the show ip bgp summary command (displays a 4–byte AS number in bold).
R2#show ip bgp summary
BGP router identifier 192.168.10.2, local AS number 65123
BGP table version is 1, main routing table version 1
1 network entrie(s) using 132 bytes of memory
1 paths using 72 bytes of memory
BGP-RIB over all using 73 bytes of memory
1 BGP path attribute entrie(s) using 72 bytes of memory
1 BGP AS-PATH entrie(s) using 47 bytes of memory
5 neighbor(s) using 23520 bytes of memory
Neighbor AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/Pfx
10.10.21.1 65123 0 0 0 0 0 never Active
10.10.32.3 65123 0 0 0 0 0 never Active
R2#show ip bgp summary
BGP router identifier 192.168.10.2, local
AS number 48735.59224
BGP table version is 1, main routing table version 1
1 network entrie(s) using 132 bytes of memory
1 paths using 72 bytes of memory
BGP-RIB over all using 73 bytes of memory
1 BGP path attribute entrie(s) using 72 bytes of memory
1 BGP AS-PATH entrie(s) using 47 bytes of memory
5 neighbor(s) using 23520 bytes of memory
Neighbor AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/Pfx
10.10.21.1 65123 0 0 0 0 0 never Active
10.10.32.3 65123 0 0 0 0 0 never Active
For the router’s identifier, the system uses the highest IP address of the Loopback interfaces configured.
Because Loopback interfaces are virtual, they cannot go down, thus preventing changes in the router ID. If
you do not configure Loopback interfaces, the highest IP address of any interface is used as the router ID.
To view the status of BGP neighbors, use the show ip bgp neighbors command in EXEC Privilege mode
as shown in the first example. For BGP neighbor configuration information, use the
show running-config
bgp command in EXEC Privilege mode as shown in the second example.
Border Gateway Protocol IPv4 (BGPv4) 217