Ethernet load balancing (was: Re: 3.0 wishlist Was: Overview of 2.2.x goals?)

Richard Jones (
Tue, 20 Jan 1998 11:20:53 +0000

I must be missing something here (again :-) ... why is
it not possible to write a special net device which just
distributes packets equally to two real net devices?
Sounds like it would just be a very thin layer. As long
as the devices have the same IP address, and are both,
say, 100Base-T, it would just work (wouldn't it?).

The only thing I can think of is that other machines on
the same subnet might get a bit confused by the fact that
a machine appeared to have two MAC addresses.


linux kernel account wrote:
> Why not reconfigure the cards as the same enet address and do the load
> balencing at the outgoing que (incoming would of course not need load
> balencing)
> On Mon, 19 Jan 1998, John Carol Langford wrote:
> > >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.
> >

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