Benefits of 1 NIC/2 IPs

Rob

Rob

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Yamba, Australia
Hello,
A job I'm working on has a PC on 2 subnets. Originally the PC was set up with 2 NICs, with a static IP assigned to each. Recently it's been changed to use 2 static IPs on only 1 of the NICs, even though the 2nd NIC is still in place and functioning.

I'm trying to understand why the tech would have done this rather than using the 2 NICs. Is there a benefit to only using one NIC, apart from saving a patch cable? The client has mentioned this PC has been running slowly. Could 2 IPs on a single NIC have an effect on this PCs internet and network access speed?
Thanks in advance.
 
Rob said:
Hello,
A job I'm working on has a PC on 2 subnets. Originally the PC was set up with 2 NICs, with a static IP assigned to each. Recently it's been changed to use 2 static IPs on only 1 of the NICs, even though the 2nd NIC is still in place and functioning.

I'm trying to understand why the tech would have done this rather than using the 2 NICs. Is there a benefit to only using one NIC, apart from saving a patch cable? The client has mentioned this PC has been running slowly. Could 2 IPs on a single NIC have an effect on this PCs internet and network access speed?
Thanks in advance.
Click to expand...

Not only could it, it absolutely 100% is having an effect, and not a small one. Using 2 IPs on a single NIC is ... well, it's just not something a normal person would do! I use two NIC's and a single IP/MAC relatively often. That's called binding. But the other way around is called foolish. The only reason I can imagine that the tech would have done that, is that he didn't know what he was doing.
 
parker.casey said:
Not only could it, it absolutely 100% is having an effect, and not a small one. Using 2 IPs on a single NIC is ... well, it's just not something a normal person would do! I use two NIC's and a single IP/MAC relatively often. That's called binding. But the other way around is called foolish. The only reason I can imagine that the tech would have done that, is that he didn't know what he was doing.
Click to expand...

There are times. I used to work for a company that manufactured printers with embedded XP controllers so adding hardware wasn't an option. A couple of times there were companies with different subnets(because of a merger) who both wanted to print to the device. Their in-house IT didn't want to make any changes so I bound an ip address for each subnet to the nic in the print controller.
 
MobileTechie said:
How has he managed to give it two different IP addresses?
Click to expand...

I hadn't seen it before either. In XP, in the NICs TCP/IP dialog there is an advanced button - in there.

I'll own up and say I had to get that info from the tech in question, along with a nice big helping of humble pie and a fair ear-bashing as well.

It's a little satisfying to hear that it might not be the greatest networking practice. If anybody wants to weigh in with their opinion please do - if general consensus indicates this might be shoddy work I'll take great pleasure in dumping his setup and changing it back to 2 NICs. I might have to send the charming man a link to this thread too! :D
 
Rob said:
I hadn't seen it before either. In XP, in the NICs TCP/IP dialog there is an advanced button - in there.

I'll own up and say I had to get that info from the tech in question, along with a nice big helping of humble pie and a fair ear-bashing as well.

It's a little satisfying to hear that it might not be the greatest networking practice. If anybody wants to weigh in with their opinion please do - if general consensus indicates this might be shoddy work I'll take great pleasure in dumping his setup and changing it back to 2 NICs. I might have to send the charming man a link to this thread too! :D
Click to expand...

Not really thought about the load side of things but never had to as it was a forced situation I was in. I suppose a lot will have to do with the collision domain setup ie hubs/switches etc

I can understand years ago but nowadays?
 
The part that makes this absolutely a terrible idea is that the thing HAS TWO NICS!!!! There is absolutely no reason to put all the load on one, and it's a waste not to use both even if it only had one IP.
 
I'm going to disagree with almost everyone so far and say that it's common practice to add extra binding to a NIC, specifically on web servers. I'll admit that the fact that he has two NICs and is not utilizing both is a little odd.
 
Why don't you ask the technician that did it? Will be interesting if you undo his work and find out they have some real screwball VLANs.

More than likely the 2ip/1nic doesn't effect anything of what the chief complaint is. Extra binding is a common practice among servers. Address the problem and ignore the 2ip/1nic for now and see if it's just a common issue unrelated to it.
 
Could be a number of reasons, maybe the other card isn't working or maybe it was discovered one card was gigabit and the other was an original card 10 or 100mbit. Usually you find one is an onboard and the other is an extra addon card. I've learned from years of going into companies if it ain't broke don't fix it. :D i've come unstuck a few times. :o

Software i've come across and worked with have been licensed against the mac address, computer name, HD id etc and making changes cause you extra work or worse.
 
Thanks for the continued input everyone, it's been excellent to get the second opinions.

Some more info about the PC in question, it's monitoring cash registers and is used to get the end of day reports from them. One of the NICs is an onboard one, both work, both are 100s. The PC is also used as a standard office machine - email, internet, banking.

I have emailed the register software tech support and they couldn't shed any light on the 1 Nic/2 IP method - it's not a requirement of the software, and the software is not linked to a MAC. I'm not planning on talking to the tech again if I can help it - aggressive & abusive was the best way to describe him.
 
My other concern, apart from the reported performance issues, is it isn't an obvious setup. It's a nice little boobytrap for the next tech who comes along if he/she doesn't spot it. The PC looks like your regular office machine, and with only one patch lead coming out of it, who's going to think to check for additional IPs? At least if it's using the 2 NICs most techs will spot it and think, "Hmm, what's going on here..."
 
Rob said:
My other concern, apart from the reported performance issues, is it isn't an obvious setup. It's a nice little boobytrap for the next tech who comes along if he/she doesn't spot it. The PC looks like your regular office machine, and with only one patch lead coming out of it, who's going to think to check for additional IPs? At least if it's using the 2 NICs most techs will spot it and think, "Hmm, what's going on here..."
Click to expand...

Is there another ip address bound to the 2nd card or is the card disabled?
 
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