Cisco Hands On Training Podcast

OSPF routes should be filtered or summarized at area border routers.

OSPF's fundamental design is that all routers in an area have the same exact view of the network topology. This is fundamentally incompatible with filtering routes within an area. As a result OSPF distribute lists do not have the same effect as RIP distribute lists. In fact, using distribute-lists within an OSPF area is dangerous.

OSPF totally stubby areas and not-so-stubby areas are ways to improve OSPF scalability. But they can be very confusing.

We cover OSPF stub areas and neighbor synchronization.

We redistribute from RIPv2 into OSPF and introduce autonomous system boundry summary LSAs and external summary LSAs.

We introduce multiple OSPF areas and network summary LSA's.

We show a single area OSPF network and go into router and network link state advertisements (LSA's) in detail.

A brief tutorial on Dijkstra's Shortest Path First Algorithm. This algorithm is used by most link state routing protocols, including OSPF and IS-IS.

RIP version 2 includes subnet information in the route advertisement. It also improves efficiency by multicasting to RIPv2 routers instead of broadcasting to all hosts.

If you run two different routing protocols in two different parts of your network, you need to redistribute routes between the two routing protocols. This session is an introduction to route redistribution by example.
In production you must be cautious about route redistribution because the route metric is not converted in a meaningful manner. This can result in routing loops.