Andy, no easy question, and prety much send some of us back to basics.. one have to take a deeper look at this command to barely get a good picture. See first link thread , good discussion on your question.. generaly no ip- route-catch improves performance for router forwarding processing desitions.
I really appreciate the response. I had problems with the reply so sorry if you get two :-)
You mention that 'no ip route-cache' improves the performance, but if 'no ip route-cache' forces the packets to be process switched I would have thought that this would have a detrimental affect.
I can see why 'no ip route-cache' would be configured if you want packet info i.e. if you were running a 'debug ip packet detail' - I'm trying to understand under what other scenarios you would configure 'no ip route-cache' under an interface.
Andy, its mostly done due to bugs on Cisco IOS : ). When Cisco initially introdced DMVPN Phase 1 on IOS 12.2(X)T, it had a lot of bugs. Spoke to spoke tunneling required CEF to be disabled on spokes (the default on 12.2(x)T ) and sometimes even disable fast switching on the hub's tunnel interface. Now we live in the CEF age, and the days for fast switching, processing switching are past us. There are other similar reasons for disabling it, but pretty rare.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...