Recursive lookup OSPF

Unanswered Question
Sep 10th, 2007

Hi,

Does ospf uses recursive lookup..?

regards,

G

I have this problem too.
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GillieLucent Mon, 09/10/2007 - 06:05

Hi ,

I don't get what you mean recursive lookup in OSPF. If you are asking about route calculation. No, its not recursive.

Generally, every router forms a link state topology of links in the area and runs SPF algorithm to calculate routes. Every router in an area has complete topology of the area. So, it calculates the route relative to itself.

Thanks,

Vijaybabu

Richard Burts Mon, 09/10/2007 - 06:30

G

I believe that there is some confusion about terms, or like Vijaybabu I do not understand what you are asking.

When we talk about recursive lookup we are generally talking about finding something in the routing table. We may be looking for a route to some destination and the routing table indicates that we get there by some next hop address. And then we have to do another lookup in the routing table to find how we get to that next hop. That is a recursive lookup.

So recursive lookup is part of resolving the content of the routing table. But OSPF does not look things up in the routing table and therefore would not use recursive lookup. OSPF helps build the routing table (and does not use recursion to do this) and it is other processes that look things up and would use recursive lookup.

If that was not what you were looking for then perhaps you can clarify your question.

HTH

Rick

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