This is the environment in this example:
YOUR ASN is 65400
YOUR IP address is 10.0.0.1
Your UPSTREAMS ASN is 65500
Your UPSTREAMS IP address is 10.0.0.2
You want to announce 192.168.0.0/16, the router will automatically exchange all the routes that it holds in its BGP table, so it might be wise to shutdown the peer while configuring it.
router# conf t
router(config)# ip prefix-list announceAS65400 permit 192.168.0.0/16
router(config)# router bgp
router(config-bgp)# local-as 65400
router(config-bgp)# neighbor 10.0.0.2 remote-as 65500
router(config-bgp)# neighbor 10.0.0.2 shutdown
router(config-bgp)# neighbor 10.0.0.2 prefix-list announceAS65400 out
router(config-bgp)# clear ip bgp neighbor 10.0.0.2
router(config-bgp)# no neighbor 10.0.0.2 shutdown
Follow me on twitter