|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical RE: CEF Load balancing...
>We have a situation where CEF in a particilar 12.0.x version >broke the BVI >interface in an IRB configuration w/ATM. Then the next version broke >forwarding between an ATM interface and a Ethernet interface in an >interesting way (I haven't tracked down the specifics on the >second case >yet.) I've seen issues where CEF drives the CPU through the roof if it is doing per-packet balancing on interfaces that reside on different VIPs. I've also seen links drop out of a CEF load-balancing group and the Adj Table hashes not purge the down interface, or keep the hash indices the same, with only two interfaces instead of three, thereby doing 67/33 balancing instead of 50/50. The workaround is to diable and reenable CEF. On the positive side, you can easily aggregate 200+Mbps across 6 DS3s with minimal CPU and smooth, per-packet balancing. Process switching on steroids it is... Besides, to uses reverse-path filtering, dCAR, dWRED, etc, you need dCEF. It is stable in 11.1.26CC1 - we use it all over for load-balancing on DS3s... Chris > >All in all, CEF works wonders, if it doesn't break something with its >extra-fancy forwarding. > >- Forrest W. Christian ([email protected]) KD7EHZ >---------------------------------------------------------------------- >iMach, Ltd., P.O. Box 5749, Helena, MT 59604 http://www.imach.com >Solutions for your high-tech problems. (406)-442-6648 >---------------------------------------------------------------------- > > |