OSPF - the final chapter (until the CCNP)

A stub zone can be configured in an area, which will replace any networks learned by the ABR with a default route pointing to that ABR.  This minimizes the routing updates that need to propagate that area, since any traffic not designated in that area gets sent to the default router.

All routers in a stub area need to be identified as such.  If the "stub" flag is not set on a router in the stub area, an adjacency will not form.  Also, networks within the stub area need to be manually summarized.  To do that, enter the command:

R1(config-router)#area 51 range 172.16.1.0 255.255.252.0

To redistribute the default route into the OSPF topology table, use:

R1(config-router)#default-information originate

And OSPF commands that can be applied to an interface:

R1(config-router)#ospf cost 2
Modifies the cost of the route to force preference over another interface.

R1(config-router)#ospf priority 22
Modifies the router priority to set the DR/BDR election to take place.  This is a best-practice in OSPF.

Comands used to verify OSPF and troubleshoot:

R1#show running-config
R1#show ip protocols
R1#sho ip ospf neigbor
R1#sho ip ospf database summary
R1#sho ip ospf interface
R1#debug ip ospf events

And onward we go!  I think it may be time for a little STP.