CEF and recursive routes

I'd always thought recursive routing should be avoided at all costs. The big reason for this was that it was always hammered into me that it forced the router to do multiple routing table lookups before forwarding the packet. So it makes sense that you would be wasting significant CPU on a busy router.

In another part of my brain (that wasn't talking to the don't ever use recursive routing part) I knew that CEF cached forwarding tables and layer 2 details so that packets could be forwarded quickly.

It was only today that I realised that the tables CEF uses actually uses the REAL next hop (the one that you get when you recurse through all the routes). This means that the router theoretically only has to recurse through all the routes ONCE - at the time it builds the initial CEF tables.

So - recursive routing is not so bad after all