Discussion on:

Set up multiple network interfaces in Windows XP

I have never seen Scenario B. Can someone please explain in more depth the reasons to use this topology, and any issues related to it. I have always seen two seperate NICs used to connect to two seperate networks.

Thanks,
Tony

I had a simliar need, a single workstation who's operator was to see information from two separate networks. No one else in each department was to see the other department's resources, so I bound the network card to both address spaces on this one machine. This was Novell in the earlier days and I had problems getting two NICs to work at the Application layer. So, the one NIC solution was easier.

Mark Raintree
Raintree Solutions, LLC

we have an exchange 2000 server on 100mb full duplex port. i have 100 users accessing during peak hours and sometimes, we experience excessive lag. i believe its the network load. is it possible to configure two cards to share load? does it makesense?

Though this article was targeted towards Desktops, it has applications towards servers as well.

What you want to look for, however, is NIC teaming. Depending on the equipment you have (switches, NIC's, etc) you can aggregate multiple NICs into asingle logical NIC.

Intel Pro based NICs support Adapter Fault Tolerance between Teaming NICs which, with the latest drivers, will also support Fast Ether Channel - giving 200Mbps Full Duplex. This way you gain fault tolerance (allowing either of the NICs to fail without losing network connectivity) AND faster throughput. The switches that the NICs attach to must support Fast Ether Channel. An example would be Cisco Catalyst switches with Port Aggregation Protocol...

Yeah This can be done easily with the help of NIC Teaming..

Easily Done you say? Care to share the minute details? Thanks

With Each Nic you Can Assign 5 if memory serves, lets say at least 4 for sake of argument. I used to configure my NT 4.0 Servers with multiple Addresses. Its pretty cool. Alot of overhead for one nic but it seems to work in a pinch.

An obvious application is where a mobile computer is moved between different networks, such as where a consultant deals with different clients. Its a pain if the network configuration has to be modified before a particular network can be accessed.

The GUI may limit you to setting only five IP addresses, but according to Microsoft "Windows NT 4.0 has no limitation on the number of IP addresses that can be bound to a NIC. The limitation is on system resources."

The Microsoft Knowledge Base Article given below is entitled "Adding More than Five IP Addresses to NIC in Windows NT."

http://support.microsoft.com/default.aspx?scid=kb;en-us;149426

(Remove any spaces in the above URL.)

I have seen posts by admins on a BIND NT mailing list claiming to have hundreds of IPs bound to single NICs.

The most I have had bound to a single NIC is about a dozen - I didn't have a reason to try more.

-Jeff

For example of this scenario, u connect to your notebook with your pc using local LAN and also connect to the internet using ADSL / Boardband network through a router.

I work with a network that has an NT server on 10. and cable router on 192. This was originally done with two small physical networks. Now we simply linked hubs on the two nets and can use on nic and one cable with two ip addresses. I had to setup a little windows route script to ensure the cable router gateway has a lower metric (higher priority) so machines don't try to find the internet through a slow satellite link on the nt network. On Win98 and Linux I am able to have one interface via DHCP and the other static, however Win2k does not allow this. Win2k will only allow multiple static IPs on one NIC. Havn't tried it with XP- the Teletubbie OS according to my 2+1/2 year old son.

Can the one NIC 2 networks scenario work if one of the Networks is DHCP? Our CEO wants to use his laptop hear and still use awol from home.Any ideas as to weather or not this will work in this scenario? Hear we are 192.... and NOVELL.

Can the one NIC 2 networks scenario work if one of the Networks is DHCP? Our CEO wants to use his laptop hear and still use awol from home.Any ideas as to weather or not this will work in this scenario? Hear we are 192.... and NOVELL.

Can the one NIC 2 networks scenario work if one of the Networks is DHCP? Our CEO wants to use his laptop hear and still use awol from home.Any ideas as to weather or not this will work in this scenario? Hear we are 192.... and NOVELL.

Now i am using it. My NIC is connected to lan and to Cable Modem. Thru switch. So i have both local and Internet IP!

A easy example of a Nic with Multiple TCP/IP address. Would be take a Win98 machine and set a Static IP for your local Intranet. Then go an add another TCP/IP protocol to your Network Neighborhood leaving it Dynamic or make Static for your Internet. Now watch how they work independent of each other.(You can on the internet and in your network working with no problems.)
If I remember right you can add 4 TCP/IP Protocols in Network Neighborhood and then 4 in the Registry or thats is both total I'm not sure with researching it again. But I do know it will work, do it on a 98 system all the time.

Here is a different scenario I've been struggling with. Our laptops have a built in 10/100 NIC which we use in the office. We have also been issued a wirelesw NIC for use when a wireless network is available. The problem arises when we need to use a DSL connection in a hotel. This needs to plug into our built in NIC. However, in the office we have to have the Net Firewall Service (provided with our AT&T Client) disabled. When on the road connecting through the AT&T Client it has to be enabled. Is there any way to set up two separate connections on one NIC. I have tried hardware profiles and that does not work. Have also tried using different user profiles and that does not work. I have resorted to putting a PCMCIA NIC in the computer but would rather solve it so I can use the built in NIC all the time.

Your company may have two or more locations You travel between company sites. Each site of course has a difference network address.
You have one laptop that can recognize either network.

I have a setup similar to what you discribed. One NIC 'Private' setup as a DHCP client from my Win2k server with no gateway specified. The other NIC is a static 'Public' NIC with the gateway specified in order to get to my company VPN. I would like to have my 'Private' NIC as my default path to anything except the VPN but can't because the company VPN won't route through NAT (it is a PIX firewall). I would like to have all my traffic except the VPN traffic go through the 'Private' NIC and only use the 'Public' NIC as the patht to the VPN.
Please help!
Greg

A heads up for anyone thinking to connect multiple domains to one PC or server with multiple IP addresses.

I remember serious problems cause by a multiple addressed PCs or server being connected to several NT domains on several IP subnets. Responses to Network discovery requests are not necessarily sent out on the Interface they were received on. Win NT and Win2K randomly picks an interface (the least busy one I believe). This can lead to election mechanisms of master and slave "browsers" going really haywire with NT/ W2K networks intermittently shutting down.

I have no idea if Win XP resolved that with ADS, but remember that Microsoft had no workable solution after many weeks and months of support calls.

i have xp pro.
connected to the internet by dsl with broadband connection type (PPPOE) .
and i have two nic but i disable one.so i use 1.
my dsl modem is connected to a hub by cross link.
my broadband is shared.
my nic is connected to the hub too.
and the problem is when i use VPN of the xp
to connect to my client i get connected but after 1 minute my connection break. and also my broadband and i have to reconnect it to the internet.
also when the connection with VPN is made for that minute i cant access to the virtual network.

thank
doron tamir

How can I make my WinXP laptop pause on boot to make changes to the network configuration. I use static IP's on two different networks while at work, then DHCP for my cable modem at home. Sure would be nice to have those three configurations already set, then choose them in a fashion similar to choosing which OS to boot to in a dual boot setup. Any help greatly appreciated!