Modifying an AS number

Modify an AS number on a router but the new AS number is not used until the BGP instance is restarted either by administratively disabling or enabling the BGP instance or by rebooting the system with the new configuration.

Because the AS number is defined in the config>router context, not in the BGP configuration context, the BGP instance is not aware of the change. Re-examine the plan detailing the autonomous systems, the SRs belonging to each group, group names, and peering connections. Changing an AS number on a router could cause configuration inconsistencies if associated peer-as values are not also modified as required. At the group and neighbor levels, BGP re-establishes the peer relationships with all peers in the group with the new AS number.

Use the following CLI syntax to change an autonomous system number.

CLI syntax

config>router# autonomous-system autonomous-system

CLI syntax

config>router# bgp
  group name
    neighbor ip-addr
      peer-as asn

Example

config>router# autonomous-system 400
config>router# bgp
config>router>bgp# group headquarters1
config>router>bgp>group# neighbor 10.10.10.103
config>router>bgp>group# peer-as 400
config>router>bgp>group# exit