Subject: Re: Multicast catching too much?
To: Michael Graff <email@example.com>
From: Havard Eidnes <Havard.Eidnes@runit.sintef.no>
Date: 11/20/1994 15:34:15
> I noticed that a NetBSD machine on an ethernet with a lot of traffic
> seems to really catch a lot of multicast packets. Is it perhaps
> catching too much?
This really depends on the ethernet card / interface you are using. If I
remember correctly, the WD80x3 cards have a hash table for doing multicast
address filtering, but this hash table is only used on a few of the
variants of the card. This means that on the variants where the multicast
address filter isn't being used, you either get no multicasts or all of
them. I suspect that other PC ethernet cards have similar deficiencies.
You are right that under these circumstances, these other protocols
(DECnet, MOP, LAT etc.) will be filtered out at the protocol demultiplexing
stage in the networking software.