Uses for two Ethernet ports ?

I'm in the process of checking out kit for a new computer build and
I've noticed that quite a few of the higher end motherboards now have
two Ethernet connections on board. I'm sure there are many valid
reasons to need two ports , but I just can't think of any right now.
Doubtless I'm being my usual obtuse self , but please enlighten me ,
why would I need two ports , presumably some external gadget that
requires an Ethernet connection ?

TIA

Pete Symonds

"Peter Symonds" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> I'm in the process of checking out kit for a new computer build and
> I've noticed that quite a few of the higher end motherboards now have
> two Ethernet connections on board. I'm sure there are many valid
> reasons to need two ports , but I just can't think of any right now.
> Doubtless I'm being my usual obtuse self , but please enlighten me ,
> why would I need two ports , presumably some external gadget that
> requires an Ethernet connection ?
>
> TIA
>
> Pete Symonds

Setting up Windows Internet Connection Sharing requires two NIC cards,
therefore a m'board with two built-in would be needed.

You can also setup linux on a system, where two NIC cards could serve as a
router or other services.

Peter Symonds <(E-Mail Removed)> wrote:

>I'm in the process of checking out kit for a new computer build and
>I've noticed that quite a few of the higher end motherboards now have
>two Ethernet connections on board. I'm sure there are many valid
>reasons to need two ports , but I just can't think of any right now.
>Doubtless I'm being my usual obtuse self , but please enlighten me ,
>why would I need two ports , presumably some external gadget that
>requires an Ethernet connection ?

You might want your machine to have interfaces on two separate subnets
or networks, e.g. one might be for provision of specific information via
multicast and one might be for routine production network.

Or you might want the machine to route traffic between two subnets.

Just two ideas.

--
Andrew W. Young (E-Mail Removed)
http://www.andrew-young.com/

Peter Symonds wrote:
> I'm in the process of checking out kit for a new computer build and
> I've noticed that quite a few of the higher end motherboards now have
> two Ethernet connections on board.

In my situation, I have two ethernet ports; this is because eth0 is on
the same network as my broadband router, and therefore public, and eth1
is used for any ethernet devices that do not need direct external
access, and/or are otherwise insufficiently protected from outside
influence.

The machines with two ethernet cards act as firewalls and proxy servers
for the machines on the 'inside' network (eth1), and this allows me to
run far more machines than I have IP allocations for (my /28 provides 13
usable addresses)

For instance, the Lexmark E120n is a nice, cheap, and unusually for
lexmark, fairly cheap to run laser printer, but it's ethernet interface
and firmware is buggy, and insufficiently insecure. I'd probably come
home and discover my paper tray empty, and the room full of paper spam,
hence it goes on the internal network.

Other reasons for having two ports is for load balancing two network
connections (perhaps you have two ADSL lines?, or an ADSL line and a
cable modem?)

Besides, with gigabit ethernet, the cheapness of ethernet interface
chips, and relative ease in writing code to use IP over ethernet
compared to USB, I suspect we'll be seeing far more devices in the
future utilising ethernet instead of USB for connectivity. We're
already seeing cheap ethernet printers, and various things like the
NSLU2 'Network Storage Link', which I would not be comfortable with on a
public network. (Ok, so most users use NAT, but I don't)

Jim

On Mon, 20 Nov 2006 21:19:07 UTC, "The s-Bray" <the-(E-Mail Removed)>
wrote:

> Setting up Windows Internet Connection Sharing requires two NIC cards,

<pedant>
What's a NIC card?
</pedant>

(ICS only needs one network connection if you have a USB modem, of
course...)
--
[ 7'ism - a condition by which the sufferer experiences an inability
to give concise answers, express reasoned argument or opinion.
Usually accompanied by silly noises and gestures - incurable, early
euthanasia recommended. ]

On Mon, 20 Nov 2006 21:00:54 +0000, in uk.telecom.broadband , Peter
Symonds <(E-Mail Removed)> wrote:

>
>I'm in the process of checking out kit for a new computer build and
>I've noticed that quite a few of the higher end motherboards now have
>two Ethernet connections on board. I'm sure there are many valid
>reasons to need two ports , but I just can't think of any right now.

Failover / Redundancy.
Running on two different subnets.
Using the computer as a gateway / router / bridge.

etc
--
Mark McIntyre

In article <(E-Mail Removed)>,
Peter Symonds <(E-Mail Removed)> wrote:
>
>I'm in the process of checking out kit for a new computer build and
>I've noticed that quite a few of the higher end motherboards now have
>two Ethernet connections on board. I'm sure there are many valid
>reasons to need two ports , but I just can't think of any right now.
>Doubtless I'm being my usual obtuse self , but please enlighten me ,
>why would I need two ports , presumably some external gadget that
>requires an Ethernet connection ?

One reason is speed. With the right setup, you can connect both ports
to the same LAN and send data out at double the rate. (or vice versa)

Gordon

Bob Eager wrote:
> On Mon, 20 Nov 2006 21:19:07 UTC, "The s-Bray" <the-(E-Mail Removed)>
> wrote:
>
>> Setting up Windows Internet Connection Sharing requires two NIC cards,
>
> <pedant>
> What's a NIC card?
> </pedant>
>
It's what you get when you pay your national insurance contributions,
isn't it?

--
Dave
mail da (E-Mail Removed) (without the space)
http://www.llondel.org
So many gadgets, so little time

On Mon, 20 Nov 2006 21:00:54 +0000, Peter Symonds <(E-Mail Removed)>
wrote:

>why would I need two ports

one example I saw had separate 10/100 and GigE ports.

Phil
--
http://www.notspot.info/ - if you can't get the Broadband you want.

"Peter Symonds" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> I'm in the process of checking out kit for a new computer build and
> I've noticed that quite a few of the higher end motherboards now have
> two Ethernet connections on board. I'm sure there are many valid
> reasons to need two ports , but I just can't think of any right now.
> Doubtless I'm being my usual obtuse self , but please enlighten me ,
> why would I need two ports , presumably some external gadget that
> requires an Ethernet connection ?

standard practice on servers so you can:
1. have 2 connections to 2 different switches for resilience.
2. connect a "front side" app and a "back end" service - web and database
are common.
3. separate link for a backup LAN.

a lot of high end PC motherboards are getting closer to low end server
designs these days, so making 1 board more flexible probably increases the
potential markets

FWIW i have a 2nd NIC card in my laptop for running Sniffer. It doesnt have
IP bound to it to minimise the risk of cross infection on a customer
network.
>
> TIA
>
> Pete Symonds
--
Regards

(E-Mail Removed) - replace xyz with ntl