trying to rig up a network switch...

[Professor Frink]

OK, here's the situation. I am the IT guy for my particular office, but I do not control the IP addressing or the network drops in the wall -- that is controlled by the folks downstairs. They have MAC filtering set up on every network drop, which is fine (it locks up if it detects a new MAC address being plugged in). I have two workstations in my office, but I'd really like to be able to connect more.

So what I want to do is this:

- add a second network card to my test PC

- connect a simple switch to that new card

- connect a third PC to that switch

So as far as MAC filtering goes, there is only one cable plugged into the wall, but hopefully I can be sharing it through the switch.

Will this work with both PCs running XP? If so, what would be the IP setup for both the new card in PC #1, and the card in PC #2? Like what would I use for the gateway? The following is fake, but let's pretend that this is the IP info for the main connection on PC #1:

IP address -- 10.50.100.200

subnet mask -- 255.255.255.0

Gateway -- 10.50.100.1

Any ideas?

[Cartoonite]

Sounds to me like what you want to set up is a slightly modified version of XP's Internet Connection Sharing system.

Based on your description, I think it should work as you intend. As for the settings, XP's ICS includes DHCP features that will allow you to simply configure the second PC for dynamic addressing. If you want to configure it manually, you can use just about any IP scheme you like.

The two cards (second card in first PC, and the card in the second PC) will each need an IP on the same subnet, say 192.168.0.1/24 and 192.168.0.2/24 (x.x.x.x/24 denotes a subnet mask of 255.255.255.0) The default gateway for the second PC would be the IP address of the second card in the first PC.

All in all, it would probably be easiest to set up ICS, and let its DHCP features manage those settings for you. That, however, is a decision you will have to make for yourself.

Hope this helps.

[Professor Frink]

I must be doing something wrong here, because it's only partially working. Again, let's pretend that this is the main IP info for PC #1's main connection (the one plugged into the wall that I can't mess with) :

IP address -- 10.50.100.200
Subnet Mask -- 255.255.255.0
Gateway -- 10.50.100.1

I then have a second NIC in PC #1, with the following IP info:

IP address -- 192.168.1.1
Subnet Mask -- 255.255.255.0
Gateway -- 10.50.100.1

(I assume that the gateway here needs to match the other NIC, since that is the router)

That is plugged into the switch. OK, so I then connect the switch to the one NIC in PC #2, and use this:

IP address -- 192.168.1.5
Subnet Mask -- 255.255.255.0
Gateway -- 192.168.1.1

I get a solid connection, and I can ping both IP addresses in PC #1 (192.168.1.1 & 10.50.100.200). But I can't ping the router (10.50.100.1), and as a result I can't get anywhere with PC #2. And from PC #2, I also can't ping the DNS server.

Am I doing anything wrong here? It only seems to be half-working. Shouldn't I be able to ping the router from PC #2?

I also tried this -- for the second NIC in PC #1, I tried setting the gateway as the IP address of the main NIC (10.50.100.200). That didn't do anything either.

Boy, I hope I'm explaining this right....

Edited June 16, 2005 by Professor Frink

[Cartoonite]

I must be doing something wrong here, because it's only partially working. Again, let's pretend that this is the main IP info for PC #1's main connection (the one plugged into the wall that I can't mess with) :

I get a solid connection, and I can ping both IP addresses in PC #1 (192.168.1.1  &  10.50.100.200). But I can't ping the router (10.50.100.1), and as a result I can't get anywhere with PC #2. And from PC #2, I also can't ping the DNS server.

Am I doing anything wrong here? It only seems to be half-working. Shouldn't I be able to ping the router from PC #2?

I also tried this -- for the second NIC in PC #1, I tried setting the gateway as the IP address of the main NIC (10.50.100.200). That didn't do anything either.

Boy, I hope I'm explaining this right.... 

Yes, you certainly should be able to ping the router from PC 2. Provided, of course, that you are able to ping it from PC 1, meaning that it has not been configured to discard ICMP traffic.

From the sounds of things, PC 2 is properly connected, but either the second NIC or some other settings aren't set up properly on PC 1. As a result, when traffic destined for anywhere other than either of the two NICs in PC 1 is received, PC 1 doesn't know how to route it and it gets lost.

Off the top of my head, the only thing I can think of is to try setting the Default Gateway for NIC 2 on PC 1 to its own IP address (192.168.1.1). I'm not entirely sure what the settings should be in this case.

If that doesn't work, I suggest trying to enable ICS on PC 1. The Wizard should walk you through step-by-step and configure the appropriate settings as you go.

[Professor Frink]

OK, I might try ICS. One concern, though -- ICS doesn't create a new virtual MAC address does it, the way bridging does? Because that would cause the port to lock up.