Re: 3.0 wishlist Was: Overview of 2.2.x goals?

John Carol Langford (
Mon, 19 Jan 1998 17:33:11 -0500

>The question is, would this incur significant overhead at high speeds?
>Wouldnt just multipath+no-route-cache be better at e.g. 10mbps?

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

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

-John Langford