More multiple NICs--one NIC, one task?

A recent thread on multiple NICs in a box was interesting. At first it
seemed it couldn't be done, but then other ideas emerged. I'd like to
describe what I want to do and why, and ask whether you think it makes
sense.

A Server 2003 box has two NICs, each with its own IP and registered
FQDN. The NICs are on the same subnet connected to a cheap "switch."
I'm not worried about WINS on the second NIC.

I'm not trying to create redundency nor to reduce network traffic.
Rather, I want one NIC (and address) to handle one type of job--web
serving, say--and the other NIC (and address) to do another job, say
database serving. I'd rather the addresses appear to be unrelated, I'd
rather folk probing the public-facing web server not notice what else is
there. I guess it's a kind of obscurity. In this day of robots doing
the probing, does this approach even make sense?

If it does, what are the networking issues?

Thanks much.

"Frank Burleigh" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> A recent thread on multiple NICs in a box was interesting. At first it
> seemed it couldn't be done, but then other ideas emerged. I'd like to
> describe what I want to do and why, and ask whether you think it makes
> sense.
>
> A Server 2003 box has two NICs, each with its own IP and registered
> FQDN. The NICs are on the same subnet connected to a cheap "switch."
> I'm not worried about WINS on the second NIC.
>
> I'm not trying to create redundancy nor to reduce network traffic.
> Rather, I want one NIC (and address) to handle one type of job--web
> serving, say--and the other NIC (and address) to do another job, say
> database serving. I'd rather the addresses appear to be unrelated, I'd
> rather folk probing the public-facing web server not notice what else is
> there. I guess it's a kind of obscurity. In this day of robots doing
> the probing, does this approach even make sense?
>
> If it does, what are the networking issues?

The motivation makes sense but it is a lot of effort
for almost no advantage. The obscurity will not
ever likely help and if you just wanted multiple
IP addresses they could be added to a single NIC.

If you really want multiple NICs for redundancy then
buy one of the "teaming NIC/driver" combinations from
a vendor.

Key phrase to search "teaming NIC".


--
Herb Martin


>
> Thanks much.

Why not just assign multiple IPs to a single NIC. Many services (Web
Servers, DB Servers, etc) allow you to specify which local IP address(es)
they are bound to. So then you could simply bind the services to the IP
address you wanted and achieve the "same" result.


"Frank Burleigh" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>A recent thread on multiple NICs in a box was interesting. At first it
>seemed it couldn't be done, but then other ideas emerged. I'd like to
>describe what I want to do and why, and ask whether you think it makes
>sense.
>
> A Server 2003 box has two NICs, each with its own IP and registered FQDN.
> The NICs are on the same subnet connected to a cheap "switch." I'm not
> worried about WINS on the second NIC.
>
> I'm not trying to create redundency nor to reduce network traffic. Rather,
> I want one NIC (and address) to handle one type of job--web serving,
> say--and the other NIC (and address) to do another job, say database
> serving. I'd rather the addresses appear to be unrelated, I'd rather folk
> probing the public-facing web server not notice what else is there. I
> guess it's a kind of obscurity. In this day of robots doing the probing,
> does this approach even make sense?
>
> If it does, what are the networking issues?
>
> Thanks much.

"Frank Burleigh" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> database serving. I'd rather the addresses appear to be unrelated, I'd
> rather folk probing the public-facing web server not notice what else is
> there. I guess it's a kind of obscurity. In this day of robots doing
> the probing, does this approach even make sense?

Not really.

> If it does, what are the networking issues?

I don't think there would be a problem in this situation but there could be
"delay" created by the fact that the machine can become "confused" about
which physical nic to send outbound packets to the Default Gateway with.

It would be more efficient to use multiple IP#s bound to the same Nic. Even
an old 10mbps Nic is 7 times faster than a T1 line, it is unlikely that user
cimming in over a T1 could ever overload even an old 10mbps Nic.

The real purpose for multiple IP#s on a Webserver Nic is so that multiple
websites can exist on the same machines and each be distinctly "indentified"
by the IP# that was queried. Although I think there is a practical limit to
how many IP#s can be bound to a Nic, so I wouldn't get too carried away with
the idea if this is a comercial webserver with a lot of sites on it.

--

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