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 (forrestc@imach.com) KD7EHZ ---------------------------------------------------------------------- iMach, Ltd., P.O. Box 5749, Helena, MT 59604 http://www.imach.com Solutions for your high-tech problems. (406)-442-6648 ----------------------------------------------------------------------