Cisco Press book question: Advanced IP Network Design ISBN:1-57870-097-3

mmorris11 · ‎01-30-2007

On pp110 of Ch5 the fifth paragraph of Solution 1 suggests that OSPF running on an interface facing the DMZ (bcast network) running another protocol (EIGRP,IS-IS, etc.) could advertise all of the networks on the DMZ as internal routes. My question is how is this done? If this router has no adjacencies on the DMZ then how is anything discovered and propagated into OSPF at all?

beth-martin · ‎02-05-2007

This can be done by enabling redistribution on the router running both Eigrp and Ospf .From Eigrp mode use redist ospf metric 100 100 255 255 1500.

mmorris11 · ‎02-05-2007

I am familiar with what you are talking about. I use this technique often. But I can't figure out what the author means. He says to run OSPF on the DMZ and while no other router on the DMZ is running OSPF and that such an interface could be passive. Thus the DMZ routes would appear as internal OSPF routes. Clearly redistribution from another IGP is not the approach to infer in this case.

sundar.palaniappan · ‎02-05-2007

I don't have the book that you are talking about. If I understand your question, why would the DMZ route show up as an internal OSPF route when there's not another router on the DMZ segment running OSPF that it could form adjacency with. As long as OSPF is enabled on an interface the route would be propagated by OSPF an internal route and it doesn't need to have an adjacency out that interface.

If I misunderstood any part of the question please clarify.

HTH

Sundar