Configuring a router ID

In BGP, routing information is exchanged between autonomous systems. The BGP router ID, expressed like an IP address, uniquely identifies the router. It can be set to be the same as the loopback address.

Note that if a new or different router ID value is entered in the BGP context, then the new router ID value is used instead of the router ID configured on the router level, system interface level, or inherited from the MAC address. The router-level router ID value remains intact. A router ID can be derived by:

Defining the value in the config>router router-id context.
Defining the system interface in the config>router>interface ip-int-name context.
Inheriting the last four bytes of the MAC address.
The BGP protocol level. The router ID can be defined in the config>router>bgp router-id context and is only used within BGP.

When configuring a new router ID, protocols are not automatically restarted with the new router ID. The next time a protocol is (re) initialized the new router ID is used. An interim period of time can occur when different protocols use different router IDs. To force the new router ID, issue the shutdown and no shutdown commands for each protocol that uses the router ID or restart the entire router. Use the following CLI syntax to configure the router ID:

config>router# router-id router-id

Example: Command usage to configure router ID

config>router# router-id 10.10.10.104

Example: Router ID configuration output

ALA-B>config>router# info
----------------------------------------------
# IP Configuration
#------------------------------------------
        interface "system"
            address 10.10.10.104/32
        exit
        interface "to-103"
            address 10.0.0.104/24
            port 1/1/1
        exit
        autonomous-system 100
        router-id 10.10.10.104
#------------------------------------------
...
ALA-B>config>router#