The following example configures the originate default route feature for BGP neighbor 10.203.134.5 using policy def_originate.pol.
def_originate.pol
entry prefix_matching {
if match any {
nlri 192.168.3.0/24;
} then {
as-path "64505";
permit;
}
}
enable bgp neighbor 10.203.134.5 originate-default policy def_originate
With this configuration, a default route is originated and sent to neighbor 10.203.134.5 only if there is a BGP route in the local RIB which matches the statement nlri 192.168.3.0/24. If a matching route exists, the default route is sent to neighbor 10.203.134.5 with the 64505 as-path prepended. If this is an EBGP neighbor, then the local AS-Number is prepended after 64505.
If the route for the match statement nlri 192.168.3.0/24 goes away and there is no other matching route in the BGP RIB, the default route origination feature becomes inactive and BGP withdraws the 0.0.0.0/0 default route from neighbor 10.203.134.5. When a matching route becomes available again in the local BGP RIB, the default route origination feature becomes active again and the default route 0.0.0.0/0 is advertised to neighbor 10.203.134.5.