Hi Jamie,
Nice design and planing :)
Generally, a default route can be originated from a BGP neighbor in 3 ways:
1. default-information originate + redistribute static (or any dynamic routing protocol having the default route - you may filter only the default route)
2. network command but must make sure the default route is present in the routing table
3. Another way of advertising a default route to a specific BGP neighbor is by issuing the neighbor default-originate command. This method does not require the presence of the 0.0.0.0/0 network in the routing table of the advertising router.
The configuration of the default-information originate command in BGP is similar to the configuration of the network (BGP) command. The default-information originate command, however, requires explicit redistribution of the route 0.0.0.0. The network command requires only that the route 0.0.0.0 is present in the Interior Gateway Protocol (IGP) routing table. For this reason, the network command is preferred.
NOTE If you are using the "default-information originate" the default route must be in the routing table, but if using the "default-originate" in front of a neighbor the default route doesn't need to be in the routing table.
NOTE The only purpose of the "default-information originate" command in BGP is to allow the redistribution of the default route in BGP. The "neighbor default-originate" command on the other hand, does advertise the default route to the specific neighbor whether it is present in BGP or not.
NOTE The default route generated via the default-originate command is kind of considered a special case and is therefore not submitted to the outbound route-map. You have two options if you want to prepend the default route.
HTH, please rate all helpful replies,
Mohammed Mahmoud.
