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Two NIC in one Laptop, Trying to utilize Dual band Router

Last response: in Wireless Networking
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February 27, 2010 2:46:03 AM

Hello all,

I am knew here and apologize in advance if I cross any forum etiquette lines. I am somewhat techie, but I have very little experience with networking. Here is the situation I am seeking advice on.

Here is the hardware:

Linksys WRT610N Dual Band N Router (2.4GHz/5GHz)
Laptop with onboard 802.11n WLAN mini-card and Linksys WEC6600N Dual-Band Wireless-N ExpressCard
OS: Vista 32bit, 4GB...
D-Link DNS-323 NAS

What I want to do is make the internal NIC connect to 2.4GHz only and the ExpressCard to only connect to the 5Ghz band. Then I want to do home network file transfers etc. on the low band and keep my internet connections on the high band.

Is any of that even possible?

Thanks
Anonymous
February 27, 2010 9:22:37 AM

Forget about it.
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February 27, 2010 1:58:53 PM

Care to elaborate on that?? Alternatives... Aren't there things that can be done with routing tables...ip to ip...DHCP reservation/mac address...metrics etc...
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Anonymous
February 27, 2010 3:30:19 PM

No, what you want can't be done.
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February 27, 2010 11:54:18 PM

It's possible, but perhaps not in the way you want, certainly not as easy as it may appear, and debatable as to whether it’s worth the effort give the rather questionable benefits (but that’s ultimately your call).

You have two network connections established from the same machine, each using a different wireless band, and both connected to the same router. Since each is using the same DHCP server, each will be configured identically except for their respective IP addresses (same subnet, same gateway IP, same dns servers(s)). For this discussion, let’s assume that subnet is 192.168.1.x.

Windows will not allow you to pick and choose network connections on a per application basis. All you can do when using multiple network adapters is prioritize them (see Network Connections->Advanced->Advanced Settings). Whichever one is listed first will be used EXCLUSIVELY since any resource (computer, NAS, the Internet) is equally accessible via either network connection. In effect, the other network connection goes unused.

The only way Windows will use different network connections is if they are actually DIFFERENT networks (subnets). IOW, if Windows can only reach a particular resource on one of several available network connections, then obviously it must choose that network connection.

Knowing that, configure the PC’s other network connection and NAS within a different subnet (let’s assume 192.168.2.2 and 192.168.2.1, respectively). Now it works perfectly, at least for that PC. Unfortunately the NAS is now INACCESSIBLE to other computers since they’re still on the original subnet (192.168.1.x).

There are several options to addressing this problem we’ve just created.

Option #1

If your NAS supports multiple IPs, then it doesn’t get any easier; just add 192.168.2.1 as a valid IP address within the NAS TCP/IP configuration. Unfortunately, while that’s simple enough to do in Windows (e.g., the NAS is of your own design), most any “off the shelf” NAS is unlikely to support multiple IP assignments/subnets.

So from this point on, we’ll assume the NAS can only be established on a single subnet, and it must be the second subnet (192.168.2.x) in order to accommodate your PC.

Option #2

Update every computer’s TCP/IP configuration to include a unique IP address in the second subnet. It will definitely work, but beware Windows doesn’t let you add additional subnets w/ DHCP enabled (at least I’ve never found a way, including “netsh interface ip add address …”). So you’ll have to configure every computer without DHPC just so you can add that second subnet. Ugh.

Option #3

Connect the NAS directly to your second network connection (not the router). Then use ICS to bridge the networks and create a gateway on your own PC. Other computers can continue to use DHCP, but you must update their routing tables so they can find the NAS. On the downside, the NAS is only accessible while your computer is running. And at that point, you could have more easily just used a USB NAS and Windows file sharing!

Option #4

Use a second router. Assign this router an IP address in the same subnet as the other router (e.g., 192.168.1.2), patch the NAS to the WAN port, assign the NAS a static IP address in the second subnet (192.168.2.1), and update the routing tables of your other computers so they can find the NAS. What make this different from option #3 is that you’re moving responsibility for the gateway to another device rather than your own computer. It’s just a convenience; ultimately the concept is the same.

Option #5

Use a router that supports two WANs. Same concept as options #3 and #4, except you don’t need to update the routing tables of all your computers; the one gateway knows how to route to either the Internet or the 192.168.2.x subnet supporting the NAS.

NOTE #1: The temptation w/ options #3 and #4 would be to add a second gateway IP to all your computers instead of updating their routing tables. But that won’t work ( http://windows.microsoft.com/en-US/windows-vista/Config... ). But if your router supports RIP, you might be able to avoid manually updating all those routing tables by enabling their respective RIP listener in Windows.

NOTE #2: If your router supports Advanced Routing options, you could update the router’s routing table to forward traffic from the 192.168.1.x network to the 192.168.2.x network. Now your computers don’t have to be changed at all; they continue to use DHCP and the original gateway IP (192.168.1.1). Any traffic destined to the 192.168.2.x network will be automatically forwarded by the router.

So yes, it can be done. Which option is best for your situation is your call. But is it worth it?

In summary, you MUST use a second subnet so your PC and NAS will work over the preferred network connection, then adjust the other computers so the NAS remains accessible. Those other computers must either participate directly in the second subnet (while remaining in the original subnet), or the second subnet must be reachable via a gateway which is either identified to those computers through their respective routing tables or the router (i.e., indirectly). If in fact you need to update all those routing tables, how they are updated will just depend on what’s available and practical.





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February 28, 2010 2:10:24 AM

Thank you so much eibgrad for your thoroughly detailed answer!! I will explore those options and post my results... I have a feeling I'll be busy for a while sorting this out.
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November 26, 2011 6:45:04 AM

Hi eibgrad,
I am using Ubuntu 11.10 on an HP notebook.

My situation is that I have two USB broadband connections(dongles) one GSM other CDMA. I also have a wifi connection available. I was wondering if you could give me some hint how I can, if it is possible, use all three or one dongle and one wifi connection simultaneously.

I have some experience of using linux for a while.
Thank you very much.

eibgrad said:
It's possible, but perhaps not in the way you want, certainly not as easy as it may appear, and debatable as to whether it’s worth the effort give the rather questionable benefits (but that’s ultimately your call).

You have two network connections established from the same machine, each using a different wireless band, and both connected to the same router. Since each is using the same DHCP server, each will be configured identically except for their respective IP addresses (same subnet, same gateway IP, same dns servers(s)). For this discussion, let’s assume that subnet is 192.168.1.x.

Windows will not allow you to pick and choose network connections on a per application basis. All you can do when using multiple network adapters is prioritize them (see Network Connections->Advanced->Advanced Settings). Whichever one is listed first will be used EXCLUSIVELY since any resource (computer, NAS, the Internet) is equally accessible via either network connection. In effect, the other network connection goes unused.

The only way Windows will use different network connections is if they are actually DIFFERENT networks (subnets). IOW, if Windows can only reach a particular resource on one of several available network connections, then obviously it must choose that network connection.

Knowing that, configure the PC’s other network connection and NAS within a different subnet (let’s assume 192.168.2.2 and 192.168.2.1, respectively). Now it works perfectly, at least for that PC. Unfortunately the NAS is now INACCESSIBLE to other computers since they’re still on the original subnet (192.168.1.x).

There are several options to addressing this problem we’ve just created.

Option #1

If your NAS supports multiple IPs, then it doesn’t get any easier; just add 192.168.2.1 as a valid IP address within the NAS TCP/IP configuration. Unfortunately, while that’s simple enough to do in Windows (e.g., the NAS is of your own design), most any “off the shelf” NAS is unlikely to support multiple IP assignments/subnets.

So from this point on, we’ll assume the NAS can only be established on a single subnet, and it must be the second subnet (192.168.2.x) in order to accommodate your PC.

Option #2

Update every computer’s TCP/IP configuration to include a unique IP address in the second subnet. It will definitely work, but beware Windows doesn’t let you add additional subnets w/ DHCP enabled (at least I’ve never found a way, including “netsh interface ip add address …”). So you’ll have to configure every computer without DHPC just so you can add that second subnet. Ugh.

Option #3

Connect the NAS directly to your second network connection (not the router). Then use ICS to bridge the networks and create a gateway on your own PC. Other computers can continue to use DHCP, but you must update their routing tables so they can find the NAS. On the downside, the NAS is only accessible while your computer is running. And at that point, you could have more easily just used a USB NAS and Windows file sharing!

Option #4

Use a second router. Assign this router an IP address in the same subnet as the other router (e.g., 192.168.1.2), patch the NAS to the WAN port, assign the NAS a static IP address in the second subnet (192.168.2.1), and update the routing tables of your other computers so they can find the NAS. What make this different from option #3 is that you’re moving responsibility for the gateway to another device rather than your own computer. It’s just a convenience; ultimately the concept is the same.

Option #5

Use a router that supports two WANs. Same concept as options #3 and #4, except you don’t need to update the routing tables of all your computers; the one gateway knows how to route to either the Internet or the 192.168.2.x subnet supporting the NAS.

NOTE #1: The temptation w/ options #3 and #4 would be to add a second gateway IP to all your computers instead of updating their routing tables. But that won’t work ( http://windows.microsoft.com/en-US/windows-vista/Config... ). But if your router supports RIP, you might be able to avoid manually updating all those routing tables by enabling their respective RIP listener in Windows.

NOTE #2: If your router supports Advanced Routing options, you could update the router’s routing table to forward traffic from the 192.168.1.x network to the 192.168.2.x network. Now your computers don’t have to be changed at all; they continue to use DHCP and the original gateway IP (192.168.1.1). Any traffic destined to the 192.168.2.x network will be automatically forwarded by the router.

So yes, it can be done. Which option is best for your situation is your call. But is it worth it?

In summary, you MUST use a second subnet so your PC and NAS will work over the preferred network connection, then adjust the other computers so the NAS remains accessible. Those other computers must either participate directly in the second subnet (while remaining in the original subnet), or the second subnet must be reachable via a gateway which is either identified to those computers through their respective routing tables or the router (i.e., indirectly). If in fact you need to update all those routing tables, how they are updated will just depend on what’s available and practical.

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!