Depends on the cpu. For a rough rule of thumb, ipeql on a Ppro-200
multipathing between 2 fast ethernet cards would just saturate the cpu.
One saturated fast ethernet card would consume about 30%-35% of the cpu.
If ipeql incurred no overhead (currently due to an extra layer of indirection
and not using the route cache), you would expect 60-70% cpu utilization.
Most of the extra 30-40% overhead is (I expect) due to losing the route cache.
The extra overhead may be acceptable on a fast cpu using only 10Mbps
connections.
The "best" solution would be to not waste the route cache - something which
doesn't seem possible just in the realm of a device driver. Alterations to
the IP stack changing the way hardware header caching is done would be
necessary.
-John Langford