multiple network cards

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#1 Sun, 07/15/2007 - 09:50
mike

multiple network cards

Hello there, i have a question regarding the use of multiple network cards, i have done some poking around at servers for sale and i always seem to see the same thing, they all seem to have dual network interface cards in them, I am thinking about dropping a second card into my machine as it only has 1 in it but before I go and do that i would like to know if there is any benefit to the use of 2 network cards over 1, the current network card in my machine is an on board 1000MBps network card but the WAN port and 4 LAN Ports all support only 100MBps i am not sure if i can open multiple instances of the same port to different machines on the router because i haven't tested it yet, I know that if i had a network backup system there would be a benefit because i could thread all the backup traffic on the 1 network card and have all the other services on the other but because there is 1 server i am not sure if using 2 cards would be beneficial or not.

Sun, 07/15/2007 - 10:42
Joe
Joe's picture

Hey Mike,

We're talking about a webserver here, right? You're not proxying, firewalling an internal network, or anything like that, right? And you're not building a heartbeat+failover system that would be happiest with a dedicated heartbeat circuit between devices, right?

Short answer: No.

Longer answer: Only if you know you need a second interface, and you know why. ;-)

If you have two pipes to the Internet, two NICs might make sense. If you have two routers to the same Internet pipe, two NICs might make sense. But in an environment where all of the things that are most likely to fail (hard disk and other components of the server, the network connection, and the routing devices) are not doubled up, it doesn't make sense to spend a bunch of effort on doubling up something that almost certainly will never fail, just because it's the cheapest one. I've seen NICs fail, but only in circumstances where other components also failed and having a secondary would have done nothing good.

Anyway, why look for ways to make your life more complicated? If you need always-on reliability, a second NIC is the least of your worries. ;-)

The reason servers have multiple NICs is because some types of workload need a second NIC, and it costs almost nothing to add a second to a motherboard. Literally, it costs a couple bucks more to buy a motherboard with two NICs instead of one. So, if you're buying a server and they want to include two NICs, fine...but no need to use it, unless you have the rest of the infrastructure to make it useful.

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Sun, 07/15/2007 - 11:00
mike

ok thanks for the quick reply, i figured i would ask that before i put the second nic in the machine and configured the router to supply a static IP addy to it

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