Three subnets and ip adresses needed

1050 pts.
IP address
Subnet mask
Windows XP SP3
I have a non-profit I am helping out with some network issues. they now have two XP pro SP3 machines on site. One was there when I came in, it has a DSL westell 6110 "dumb" modem connecting them to Verizons dsl. The original pc has a static ip, gateway and dns servers. the subnet of that machine is 255.25..255.0. They have a VPN to the local public transportation service with a subnet of They want to share files between the two in-house pc's. I am able to get that to occur by using a second NIC on pc1 with a static address using subnet and the same setup static and subnet on pc2. However when they launch the vpn, they can no longer share files, because the vpn is using the same subnet as the static NICs. What other subnet and address range can I use to allow for conectivity between these machines even when the VPN is in use? It is not necessary for pc2 to connect to the internet, and they do not have alot, or any money for new equipment. I was thinking a wireless router setup with the correct static information, but if I can just use the setup they have now, that would be fine.

Software/Hardware used:
xp pro sp3, dsl

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Sorry, the subnet of pc1 is

The subnets aren’t the most important part. You need to use different IP ranges on the NICs.

Assuming that nic1 on PC1 is a public IP address, you need to use a private IP range on the other NIC such as (and for PC2) with a subnet of If the IP that you get when you VPN into the other company is in that IP range then you’ll need to pick a different one like and


My only questions is: why is the Public WAN IP going straight from the ISP to the PC? I recommend setting some sort of multi-port router (get a good one at best-buy for $60) and put the Public IP on the router.
Then, like everyones saying, make sure your internal IP range is unique from the remote VPN LAN, configure PC 2 w/o a gateway IP , etc etc…

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  • Stevesz
    I do not see why you added a second NIC to the connected PC. The VPN connection can be made with just the one NIC. To resolve the sharing problem, get a cheap wired router/switch for them (if you are anything like me, you may just have an old one hanging around. Connect both machines to that, but set it up not to act as a DHCP server. Give both machines a static IP address. If you do not want the second to have internet access, simply do not add the Gateway address and DNS address(es). Map a drive to the second PC using the IP address instead of a name. Map the second machine to the first using the IP address also.
    2,015 pointsBadges:
  • Chippy088
    Is the IP address on pc1 nic1 static or allocated by the isp? What are the 3 IP addresses you are using, and which NIC are they set up on? It is easier to help if I know these things.
    4,625 pointsBadges:
  • swinehart6803
    Sorry for not spelling it out as clearly as I should have. PC1 has NIC1 with a static address and DNS assigned by the ISP provider on subnet and cannot be changed PC1 has NIC2 with no address, subnet or DNS as of now PC1 has a VPN with a static IP and DNS assigned by the VPN provider on subnet and cannot be changed PC2 has NIC1 with no address, DNS or subnet as of now I need an subnet and address for NIC2 on PC1 and NIC1 on PC2 that will not conflict with either existing static subnets but allow for "sharing" traffic between the two Internet is not needed on PC2
    1,050 pointsBadges:
  • The Most-Watched IT Questions: July 13, 2010 - ITKE Community Blog
    [...] Swinehart6803 needed three subnets and IP addresses, and Mr. Denny, Stevesz and Chippy088 got in on the [...]
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  • swinehart6803
    Just got back from there and I have all the ip addresses and vpn info I may have to have them get a wireless router to solve this issue but here is goes STATIC IP ON PC1 NIC 1assigned by IP provider IP- SM- GW- STATIC VPN ON PC1 NIC 1 ASSIGNED BY VPN PROVIDER IP- SN- GW- Would need a static IP and correct SN for PC1 NIC2 and PC 2 NIC1 to allow for "sharing" My attempts dont work, I cant ping or see the other pc. When I tried using other Subnets. I went to subnet to try a few and got no results. Is a wireless/wired router the way to go on this one?
    1,050 pointsBadges:
  • RGunther
    If you are a cable to go from PC1 Nic2 to PC2 Nic1 you will need to use a crossover cable since they are like devices. As for IP addresses, you could move to 192.168 range. Example use PC1 Nic2 and PC2 Nic1 can have Just make sure to leave the gateway blank on PC1 Nic2. If you are using a switch/router for this you can use a straight through cable. Ryan Gunther
    650 pointsBadges:

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