Question to the networking experts: Dual-port NIC

I need to design a redundant connection to a PC acting as server. There will be two LAN switches (interconnected by means of a crossed cable) and the PC which should have a dual-port NIC.

What do I need to look out for when purchasing the hardware (PC with dual-port NIC)?
I assume the PC is standard and have seen that dual-port NICs are available, but are there e.g. different kinds of dual-port NICs?

What about the “soft part” - is there any special SW (besides the driver) required to support such a card and the required function, i.e. automatic switchover in case of a single-point of failure in the connection (e.g. one LAN cable broken or one LAN switch failed)?

Any advise appreciated.


You can get 2 or 4 port ethernet cards. They aren’t too common, being mostly useful on servers, but they are out there. Be careful to make sure it is actually a multi-nic card. There’s also cards with one nic and a 4 port hub or switch built into the card, not the same thing at all.

As for the failover part, that requires additional software. Since you didn’t specify, I assume you mean Windows. I know some of the expensive firewall packages have NIC failover, not sure if there’s cheaper stuff available. You might want to look into clustering as well. NIC and switch failures are pretty rare compared to a server crashing or a disk going out. With clustering you can have multiple machines and can failover to a whole 'nother system.

Intel has NIC’s for Servers, after you install all the cards and there s/w. You can set the NIC’s as a team in redundant connection mode or Load balancing mode etc.

You need to buy the Server version of the NICs not the Desktop version.
Are you planning 100Mbps or 1 GB version ?

yah what the other guy said… of my years of doing network/pc ive only had the network hardware fail once… and that was due to a power surge taking out a mau(token ring yummi) im not sure your requirements(ie load balancing) but is their any advantages of using a multi port nic? like for it being fail safe… but lets say the nic was too fail… what are the chances only one port would fail? like why would you just not get a 2nd NIC? i forget how the pci bus works… is it shared between all other pci devices? i think so…

Thanks so far. The purpose is for redundancy only, not load sharing or clustering.
OS will be Windows (2000).

There is no concern as to the availibility of the PC and it’s components (hard-disks, power supply etc.) or the network card itself, but I need to protect against a single point of failure, which could be the LAN cabling or the LAN switch.
Since I can’t connect one port to two switches, I need a dual-port NIC.

The software mentioned - is it included with such dual-port NICs?

It possible to have 2 network cards on one PC, it can be used for extra security, to have 2 seperate networks: 1 for the internet, and 1 for the LAN. Or to set up a firewall on a linux machine between your LAN and the internet.

I’m guessing the people who do these things use 2 cards instead of a 2 port card ?

Yes, AFAIK this is done with two NIC, one connects to the intranet (office LAN) and one could connect to the internet (via a Firewall/Router).
However I need it strictly for connecting one PC to two LAN switches. If I use two seperate cards it won’t include the required SW I assume and as mentioned redundancy of the card itself is not a concern.

If you use Intel cards then you have s/w for doing this even with two seperate Intel NICs