[c-nsp] Symmetric load-splitting with CEF

[Oliver Boehmer (oboehmer)]

Tomas Daniska <> wrote on Monday, November 19, 2007 3:06 PM:

> Hi all,
> 
> I am aware that symmetric load splitting to transparent stateful
> devices (such as IPS, SCE etc...) is possible with EtherChanneling
> (with some careful balancing algorithm design), and is available on
> c6k5 for some time.

Right, but I would not call this "symmetric". You always need a
sufficiently large number of flows to achieve symmetric load.

> But - c6k5 do not support cross-chassis EtherChannels with current
> supervisors; so if topological redundancy is required, L2-based LB is
> not the way to go. I've noticed someone somewhere saying this is also
> possible with CEF at L3, but I can find no reference for such
> solutions. 

Yes, regular CEF load-balancing also achieves a similar result, with the
same caveat as above.

	oli