Deriving the router ID

The router ID defaults to the address specified in the system interface command. If the system interface is not configured with an IP address, then the router ID inherits the last four bytes of the MAC address. The router ID can also be manually configured in the config>router router-idcontext. On the BGP protocol level, a BGP router ID can be defined in the config>router>bgp router-id context and is only used within BGP.

If a new router ID is configured, protocols are not automatically restarted with the new router ID. The next time a protocol is 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 syntax to configure the router ID.

config>router 
    router-id router-id
    interface ip-int-name 
        address {ip-address/mask | ip-address netmask} [broadcast all-ones | host-ones]

Example

The following is a sample router ID configuration output.

A:ALA-4>config>router# info
#------------------------------------------
# IP Configuration
#------------------------------------------
        interface "system"
            address 10.10.0.4/32
        exit
     . . . 
        router-id 10.10.0.4
#------------------------------------------
A:ALA-4>config>router#