Bridging function or NAT

Started by Mark


Bridging function or NAT   04 April 2006, 18:08

Hi, I'm currently hoping to use Bandwidth Manager to offer limited wifi access in my neighbourhood, but I've run into a few snags.

I have an ADSL internet connection, for which I use a D-Link DSL-G604T router. The router's IP address on the LAN is with the subnet It performs NAT and DHCP. So the computer I'm running Bandwidth Manager on is the gateway computer (Windows XP Home Edition SP2) to the Wireless LAN, and on the wired LAN it gets a dynamic IP in the 10.1.1.x range.

This is where I get confused with the bridging function.

1. On the NIC which is connected to the Wireless Access Point, does it have to have a static IP in the 10.1.1.x range? I tried this but my gateway computer lost internet connectivity. Clients cannot access the internet either.

2. If I use a different private IP class on the WLAN interface, ie: 192.168.0.x with the subnet or 172.16.1.x with the subnet, I get internet connectivity back on the gateway PC, however the two networks are then using different subnets and therefore cannot communicate, even if bridged in Bandwidth Manager.

3. In both scenarios the clients cannot obtain an IP address from my router's DHCP server, so I must configure them manually. What should I use as the Default Gateway? The IP of my router, or the IP of the second NIC on the gateway computer?

4. When I enabled Windows Internet Connection Sharing to create a second NAT and disabled Bandwidth Manager's bridging function, I got full connectivity on both the gateway PC and the clients. However, ICS makes me set the IP on the second NIC to with a subnet of This solution would be great if only I didn't want to use this IP range because it limits the number of connected WLAN clients to 254 at maximum. Ideally I want to use the 172.16.1.x range with subnet so I can have well over 254 clients connected (I have plans to expand). Setting the second NIC's IP to with subnet with ICS still enabled results in ICS no longer working and loss of internet connectivity on the WLAN.

So to recap:

1) Do the IP address ranges and subnet masks need to be the same on both NIC's and networks for Bandwidth Manager to bridge them correctly?

2) If so, how can I get all clients and the gateway PC to have full internet connectivity?

3)What do I set as the Default Gateway on the client PC's?

Thank you for your time. If you need me to make a map of my network I will do that.


Re: Help with bridging function or NAT please   05 April 2006, 07:40

Perhaps something to consider until Andrew replies...

I would recommend setting a static IP on both NIC of the gateway PC and disable the Internet Connection Sharing on the gateway PC since it's being Nat'ed elsewhere. The Interface that is connected to the Internet Router, should be static and for example subnet, and the gateway set to, and the dns server set to or your ISP's. This is so the gateway PC also has normal Internet access.
On the LAN side of the gateway PC, make sure it's interface is also static subnet You could set the gateway and dns aswell like you did on the first one although I don't think this matters as much.

Then go in to bandwidth manager and enable bridging.

You may need to go in to your DHCP server of your router and make sure the addresses of the gateway PC, & 6 are then reserved so as not to try and hand out those IP's to clients.

That should be pretty much it, and it should pretty much work, however sometimes there's other odd factors independent to each persons setup incase they are running antoher router, or other software like proxies etc...


Re: Help with bridging function or NAT please   05 April 2006, 14:34

Thanks for the reply Gavin.

I tried what you said but alas no internet connectivity on either the gateway PC nor the clients. I think the gateway PC is confused as to which connection to use for it's internet access. The moment I disable the second NIC, it can access the internet fine. I enabled Windows Bridging on the connections and it works fine, but then Bandwidth Manager doesn't work anymore. It may be that the gateway PC just isn't very good for this sort of thing, I've had troubles with it in the past. I might try another computer instead, just to rule out that factor.


Re: Help with bridging function or NAT please   05 April 2006, 15:32

Might be worth a shot. Although if the bandwidth manager is in bridge mode, it shouldn't effect the clients at all unless there are specific network adaptors that the bridge mode is less compatable, Andrew? Was Windows briding disabled when you tried to bidge bandwidth manager with static IP's on each card?

Re: Help with bridging function or NAT please   05 April 2006, 17:40

Yes, Windows Bridging was disabled when I enabled Bandwidth Manager's bridging. I used a different computer, assigning each of it's NIC's static IP's, however, I never even got to the stage of installing Bandwidth Manager on it because the instant I give the second NIC an IP that is in the same range as the first, internet connectivity stops altogether. If I disable that adapter, then connectivity resumes. It's definately something to do with the computer not knowing which adapter to look for the internet connection on. It's really frustrating. Any other ideas would be greatly appreciated.
SoftPerfect Support forum - Andrew avatar image

Re: Help with bridging function or NAT please   05 April 2006, 23:15

Hi Guys!

Sorry for the late reply. First I'd like to clarify something. Do I understand initial setup correctly?
ADSL/NAT/DHCP( - Server PC with BM - Wireless AP - Wireless clients
The problem is how to provide all the wireless clients with managed internet access, right? So, basically we have two options: a) use ICS on the PC b) Use bandwidth manager bridging on the PC. In any case we must be sure that the wireless AP is also in bridge mode and does not do any routing or forwarding. This is important, because if it does, we are unable to catch the wireless clients on the server, we will see only the AP's IP address, all the wireless will be hidden behind the AP.

Let's see these options in details.
a) Using ICS. As Mark told it is an easy solution but works just for 255 addresses due to addressing scheme limitations. If you were runnung Windows Server, you then could use RRAS (Routing and Remote Access Service) that supports NAT better.

b) Using bridging. Windows bridging must be disabled. Adapters must be given any IP addresses from the range. For example, and (it would be better if they are out of DHCP scope in the ADSL modem to avoid conflicts). Then merge the ethernet interfaces with the bandwidth manager. Remeber, in this case the server becomes a _transparent_ bridge. That is, the default gateway on the wireless clients must be It will go through the bridge.

Let me know if this helps or not.

P.S. In the future I hope we'll include NAT into the bandwidth manager to avoid such situations.

Re: Help with bridging function or NAT please   06 April 2006, 07:05

Will bandwidth manager not catch traffic if routing on the wireless AP to the DSL router is performed without NAT?

The problem with bridging on this setup as Mark's mentioned, the whole thing dies if you set an IP with in the same subnet mask on the second adaptor. The first adaptor also locks now without bandwidth manager, ICS or windows bridging aswell.

You're not using Windows 2000 Professional by any chance? I've had this happen once. It turned out that I was changing the IP on the second NIC while it was trying to get an address via DHCP to start with. The Win Interface showed the new static IP, but the ipconfig /all command showed it was still trying to renew/release a DHCP first. This took about 4 minutes to wait for it to correct or until the second NIC had a valid DHCP server somewhere to get an IP from first. It takes yonks for Win2K sometimes to figure out there finally is no DHCP available and assign one of those silly Microsoft 169.X.X.X addresses. Probably not what you're experiencing but it's another red-hearing so to speak that can confuse some.


Re: Help with bridging function or NAT please   07 April 2006, 14:51

Hi Andrew and Gavin,

Thanks for the help. I think I will purchase a copy of Windows 2000 Server to use RRAS(cheaper than Server 2003). Bandwidth Manager works fine with Server 2000 I assume? There are a lot of features I could use on a Server version of Windows as well, so it should be a good investment.

And to answer your question Gavin, I'm using Windows XP Home. I did try an availiable Windows 2000 Pro computer with exactly the same results as the XP machine.

Can't wait for that NAT feature if it is implemented Andrew. In the meantime I'll work on getting a copy of Win2k Server.

SoftPerfect Support forum - Andrew avatar image

Re: Help with bridging function or NAT please   07 April 2006, 16:26

It will work on W2K server just fine. Actually the development platform and lots of testing are done under Windows 2000 Pro and Server. If you have any problems configuring it then post a message here.

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