True CEF is preferred over FS. My point is by using DCEF the RSP is freed up from processing lookups (FIB and Adjacency Tables). The VIP's take that over. If you just have CEF enable and not DCEF the RSP does the work. That's why they came out with DCEF - to distribute a copy of the FIB and Adjacency tables to the VIP's so they can handle it and hence free up the RSP.
Hope that helps, Ian www.ccie4u.com Rack Rentals -----Original Message----- From: Zsombor Papp [mailto:[EMAIL PROTECTED] Sent: Thursday, July 03, 2003 8:02 PM To: Sales Cc: [EMAIL PROTECTED] Subject: RE: fast switching v.s. cef switching [7:71862] CEF is better than fast switching for sure. Distributed CEF however doesn't free up memory on the RSP per se, as the RSP still has to build up and store the CEF table. I am also not sure whether the VIP cards can't do switching on their own without CEF. You sure about this? Thanks, Zsombor At 09:25 PM 7/3/2003 +0000, Sales wrote: >Couple of other minor points to add. The fast switching cache is on the >RSP and uses it's memory as does CEF. You can distribute the CEF tables >to VIP (versatile interface processors) cards. This enables the VIP >cards to store and process the packets based on the CEF tables on the >VIP cards. Uses memory and CPU on the VIP and hence frees up the RSP >for other tasks. > >We use distributed CEF quite a bit along with Turbo ACL's for better >performance. > > >Ian >www.ccie4u.com >Rack Rentals > > > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of >Zsombor Papp >Sent: Thursday, July 03, 2003 2:43 PM >To: [EMAIL PROTECTED] >Subject: Re: fast switching v.s. cef switching [7:71815] > >At 04:37 PM 7/3/2003 +0000, Jans van Deventer wrote: > >Does the CEF cache and Fast Switching cache reside in router memory? > >Yes. > > > And > >if so what makes CEF faster > >than Fast Switching? > >The cache structure is more efficient. > >Thanks, > >Zsombor > > > >Regards, > >Jans > > > > >Fast switching builds a forwarding cache on the fly, based on the >packets > > >that reach the router and need to be switched. CEF builds the "cache" >(CEF > > >table) based on the routing table, independently from the traffic. > > > > > >The fast switching cache does not (necessarily) contain all the >information > > >that's in the routing table; it starts out empty and entries are aged >out > > >of it later on. Consequently the first packet of every new "session" >going > > >through the router must be process switched, ie. a routing table >lookup >and > > >cache population need to take place before the packet can be >forwarded. > > > > > >The CEF table always contains all the information that the router has > > >access to, it changes (almost) immediately after the router receives >a > > >routing update. > > > > > >Thanks, > > > > > >Zsombor > > > > > >At 03:17 AM 7/3/2003 +0000, wj chou wrote: > > > > > > > > >>Can anyone tell me what's the difference between fast switching and >cef > > >>switching? > > >> > > >>thanks first! > > >> > > >>Ellie > >-- > >================================ > >Jans van Deventer > >Phone: (55-61) 361-1466 > >Fax: (55-61) 234-8722 > >www.rhox.com.br > >================================ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=71869&t=71862 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
