In order for Border Gateway Protocol (BGP) to advertise a classless network generated by issuing the network BGP configuration command, a valid route must exist in the routing table.
A valid route is an exact route matching the network/address pair used in the network BGP configuration command.
For more information on BGP route advertising issues, refer to the Troubleshooting BGP Route Advertisement section of Troubleshooting BGP.
For more information, refer to Troubleshooting When BGP Routes Are Not Advertised.
BGP Prefix Origination Method
Using network command
Prefix/network does not exist