I would enable CEF if you have either equal-cost paths to load-balance across, or if your routers have cause to do recursive route-lookups. CEF obviously enables intelligent load-balancing across multiple paths, and also enliminates recursive lookups through pro-active FIB building from the route and ARP tables. Personally I would probably go with CEF across the board - the technology is a *lot* more stable now - it has been around since the 11.1CA/CC "geek-track" images - saying that I am from an ISP background so we have it on everything, so I guess I am biased. Historically there was a joke which went: Q: How do you spell CEF? A: !.!.!.!.!.!.! relating to the tendancy of CEF to drop alternate packets under certain circumstances. Bear in mind finally that if you have a large enterprise network, that some of the high-end kit *has* to use CEF (or dCEF) - notably the 85XX, and 12XXX series. A ----- Original Message ----- From: "NRF" To: Sent: Wednesday, May 16, 2001 7:07 PM Subject: How helpful is CEF in a non-ISP-type environment? [7:4713] > I was wondering if anybody has ever been able to compare the performance of > routers doing CEF switching vs. fast switching (or one of its variants like > optimum switching) in an environment where routes change rarely (like an > enterprise, not an ISP, as I think we all agree that CEF is very useful in a > highly dynamic environment like an ISP). Yes, I am well aware of CEF's > advantages, like that you can quickly switch all packets of a flow without > having to process-switch the first packet, that there is greater > intelligence in CEF as regards to subnet masks, and that you can do more > kinds of load-balancing. All very useful in an ISP environment, I'm sure. > > But I have also heard that the CEF implementation still has some bugs, > particularly in the lower line of routers like the 2600. So my question is, > in an enterprise environment where there are maybe only 10's or 100's of > routes, and those routes rarely change anyway, how much better is CEF really > compared to, say, fast-switching. If your routers are CEF-able, should you > always have it on, no matter how small your network is? If not, how large > would you say a network has to be before CEF becomes viable? Naturally, > there is no hard and fast rule. I am just looking for a general synopsis of > what people think. > > Thanx > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=4770&t=4713 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
