Changing the router ID number in the BGP context causes the new value to overwrite the router ID configured on the router level, system interface level, or the value inherited from the MAC address. It triggers an immediate reset of all peering sessions.
Example
config>router>bgp# router-id 10.0.0.123
This example displays the BGP configuration with the BGP router ID specified:
ALA-B>config>router>bgp# info detail
----------------------------------------------
no shutdown
no description
no always-compare-med
ibgp-multipath
. . .
router-id 10.0.0.123
----------------------------------------------
ALA-B>config>router>bgp#