*BSD News Article 94837


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From: "Ted Mittelstaedt" <tedm@portsoft.com>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Two network adapters
Date: 29 Apr 1997 19:40:46 GMT
Organization: Portland Software
Lines: 41
Message-ID: <01bc54d5$518a0be0$6601a8c0@teds.portsoft.com>
References: <01bc5419$dbc57e00$17d1d0cd@fred.scaleable.com> <5k4glt$h54@ui-gate.utell.co.uk>
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Brian Somers <brian@shift.utell.net> wrote in article
<5k4glt$h54@ui-gate.utell.co.uk>...
> In article <01bc5419$dbc57e00$17d1d0cd@fred.scaleable.com>,
> 	"Fred Young" <myoung@scaleable.com> writes:
> > I installed a second network adapter in my machine that 's on the same
> > network as the first network adapter. I gave the second adapter an IP
> > address using ifconfig and the machine responds to the second adapter,
but
> > here's the problem. All responses are sent from the first adapter even
> > though the source IP address is the IP address of the second adapter.
What
> > am I doing wrong?
> 
> What do you expect it to do ?  It's finding the first routing table
> entry and obeying it.
> 
> You should add a static route (to localhost) for the new IP number.
> 

This will only work for the specified host.

The thing is that assuming your first network adapter is a good one with
the ability to transmit fast enough to saturate the ethernet (most modern
adapters can do this, even ISA ones) then you don't get any faster network
throughput by putting multiple network adapters in the machine and
connecting them to the same physical network.

Your probably confused by some of the schemes that Novell came out with
which put multiple NICs in the server to "double" the bandwith.  What they
didn't tell you is that these had to be plugged into a switching hub that
had special software on it to recognize what was going on.
 
Network throughput is gotten by dividing the number of hosts over the
network bandwith.  The only way to modify throughput is by changing one of
these two
variables.  You can either reduce the number of hosts by segmenting them
into additional physical networks using either switching or routing, or you
can increase the bandwith by going to 100baseT or some such.