Workstations: 2 NIC, Same IP Address

Sounds like someone cut and pasted in your spec sheet. How many networks do you have connected to each machine? You could have two networks attached to each machine which are connected to two different servers. Each NIC could have the same address for the two different networks. This may make future troubleshooting confusing so I would make sure the networks were at least named uniquely.

I have a computer with two networks: a NIC and the onboard LAN, (so essentially two NICs). I have two networks; each with a different server. I disable one interface then enable the other. Each NIC uses the same IP address and the host also has the same address. It was necessary to use either one or the other due to this configuration.

If you do have some kind of hot stand-by configuration I would hope that whoever spec'd out your design would have informed you of this and how it worked. This would be pretty in-depth considering the always-on nature of the Ethernet standard (that's another assumption).

While I agree with Pete, as doable, sort of, it is still a lazy and dumb idea creating more problems, than it solves.

For example, the 2 ethernet connections may go down, or one of the PC may go down. How will the software handle that in a switchover? IP is explicitly available to higher level of the software. NIC is used on the physical and next level, implicitly, if I recall correctly. Not available, except for diagnostic software.

The clean way is on the Application level, designating one IP as the backup or whatever for another IP. Then the Application has a chance to do a clean cutover. Imagine, instead a cludge.

The cludge has one advantage, if I can call that. Nobody understands it, maybe not even you. Iob security, as long as you are tolerated.

I agree. It's just silly. It is possible to run 255 different subnets over the same cable, so if one server goes offline, the workstation user can just change IP's.

Old versions of Windows required a restart to change network configurations; newer Windows doesn't require a restart, and since XP has been able to manage two IP's on one NIC, as when you are running a network printer on a different IP from that used for internet access. OSX can switch IP's in four mouse clicks.

You can not have the same IP address on two NICs on the same network, period!

Either there's one NIC without a cable plugged in or the NICs are on different networks.

Please provide more info about you setup.

Thanks for the comments, The spec call the network is ethernet standard TCP/IP communication.Each computer is provided with 2 network adapters sharing the same IP address, should one of the network adapters fail, the other one takes over immediately. We have 2 servers main and back up and our os is windows server. The network is using fiber optic ring and 4 fiber optic switches and this fiber optic switches with rj 45 connector for Cat 5 cables, and this connected to workstation each workstation has 2 Cat 5 cables going to different fiber optic switches.

It almost seems a little overboard. It would be easier to program if you had two NICs with two separate IP addresses. The computer could then be set to use either one or the other connections based on network activity.

If one is busy, use the other. If one is down it would be the same effect.