isolating network traffic to a dedicated switch.

hello,

I have Server1, Server2, and Server3. Each server has 2 NICs (NICA and
NICB). Server1-3 have a lot of interserver traffic, I want to have all the
traffic between these 3 servers to use a dedicated GB switch attached to
their second NIC (NICB). All other traffic should go through the first NIC
(NICA), which is connected to the rest of the LAN.

1)is this the way to isolate traffic?
2)how do I make sure that interserver traffic between these 3 serevrs uses
NICB?

"Pete" <(E-Mail Removed)> wrote in message
news:A6193DB8-5A3E-4C81-831E-(E-Mail Removed)...
> hello,
>
> I have Server1, Server2, and Server3. Each server has 2 NICs (NICA and
> NICB). Server1-3 have a lot of interserver traffic, I want to have all
> the
> traffic between these 3 servers to use a dedicated GB switch attached to
> their second NIC (NICB). All other traffic should go through the first
> NIC
> (NICA), which is connected to the rest of the LAN.
>
> 1)is this the way to isolate traffic?

First,...the traffic is already isolated if you run a Switched
network,...nobody should be using Hubs now-a-days.

Second,...in direct answer to the question,...
How to do this in the "generic sense",...each "set" of Nics (one from each
server) has to be on a different IP Segment. You have to come up with a
different "fake" name for each server and there needs to be one of these
names "invented" for each IP Segment. You cannot use the real server name
because that will always resolve the same IP# and will always follow the
same path. The only alternative to the "fake names" to to allways specify
the destination using the IP#, which is not always possible. These "fake
names" can be manually created as records in the DNS Server that is already
being used by the machines. It could also be done in a WINS server.

> 2)how do I make sure that interserver traffic between these 3 serevrs uses
> NICB?

You don't. This is a trainwreck waiting to happen. Traffic does not self
exist,...it comes from an Application or Service, and that is where the
focus needs to be. The Application or Service that generates the traffic
has to reference the Destination via one of the fake names mentioned above.
In many cases this is just not even possible.

This whole idea is built on a misconception (IMO) that a single nic would be
overload and not handle the traffic. This is wrong and you would be totally
amazed at how much a single Nic can handle on a fully switched & full duplex
circuit. People also forget that bandwidth is "shared" on a Hub but is
*dedicated* on a Switch because a Switch creates a "virtual circuit" between
the two communicating hosts that is not shared not ever even "seen" by any
other host. The one place with the heaviest load is the Switch's Backplane,
however many of those run at 3gig or better.

You should not try to solve perceived problems that may not really exist by
using solutions that are contrary to the way TCP/IP, Layer2 switching, and
Layer3 routing actually function. At least that is my opinion of this
subject anyway,... and there are about 3 or 4 questions a week in the groups
identical to this one.

Now people sometimes create a Stub Segment using the technique I described
to run Tape Backup over a different wire. Tape backups are essentially a
"filecopy" operation and a "filecopy" is the highest bandwidth consumer that
exist,...video & audio streaming are not, that is just a stereo-type left
over from the dialup internet access days. So it might make some sense to
do this in such case,..but I still do not do it. I have run multiple tape
back ups over the regular LAN wire at the same time and it was not even
noticed. I don't believe in solving problems until there is a real problem
to solve. That's not to downplay "prevention",...but I don't try to prevent
things that have been demonstrated to not happen or I don't believe are
going to happen.

--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com