Hello, I have a HP DL380-G7 server with W2K8-R2 and has 4 available NICs. I had multi-homed this server but will be setting up NAT to take care of the multi-home side of things. My questions is if there would be any impact of using 2 NICs on the same subnet? Both NICs will have a unique IP address and will be accepting NAT'd traffic by service/port. Thank you in advance

Generally, there is no advantage to setting up two NICs on the same subnet. If you are considering to set up a "load-balanced" or "Failover" design, you'll need to implement a third party "Teaming" solution. HP and Intel come to mind. Otherwise, I dont see the point. Visit: anITKB.com, an IT Knowledge Base.

The NICs will be set to 'Auto' for speed/duplex and the backbone is 1Gbps. This server will host database services and so my reason for implementing it this way is to see if segregating services by NICs on the same subnet may equate to better throughtput in terms of response time.?.

What you are asking is common. The idea is to have multiple NICs and try to force traffic, depending on the service, via one NIC vs the other. The problem is that it doesnt generally work out that way. The computer is going to send outgoing traffic via the NIC according to its local routing table. There is nothing else native within Windows that will allow you to really couple certain services with specific NICs. If you want to ensure that you have enough bandwidth, you best option is to look at "Teaming" the NICs. Teaming has been around for a while (been working with it for about a decade now). I wouldnt recommend that you add this layer of complexity unless you know for a fact that you are going to be using this much bandwidth. You would be suprised on how many servers are OK with simply 100 mb connections. Visit: anITKB.com, an IT Knowledge Base.

I agree but see 'teaming' as having limitation(s) to the capacity of back-bone. This hasn't proved to work for us in the past and MS 'load-balancing' is a software-based load-balancing solution as opposed to a hardware-based load-balancing solution. Thanks for your comments.

Ok, the teaming is not really related to the software/hardware load balancing. I just recommended it as a thought because for most situations it appears that people try to connect multiple NICs into the same subnet to create an HA solution. So, not sure exactly what you are trying to accomplish based on your description, but to answer your question...if you do proceed and place both NiCs on the same segment, you could set up NAT translation so that each NIC is "assigned" to a seperate NAT rule.Visit: anITKB.com, an IT Knowledge Base.

Hi nfts, Thanks for posting here. >My questions is if there would be any impact of using 2 NICs on the same subnet? I agree with JM since this is really no a recommended configuration on Windows Platform, you will be aware of the explanation form the article below: Expected Behavior of Multiple Adapters on Same Network http://support.microsoft.com/kb/175767 > This server will host database services and so my reason for implementing it this way is to see if segregating services by NICs on the same subnet may equate to better throughtput in terms of response time.? If the purpose is trying to improve the networking performance with multi NICs on a single host, please also take look the introduction of each possible configuration in the designing article below: Using the multiple NICs of your File Server running Windows Server 2008 (and 2008 R2) http://blogs.technet.com/b/josebda/archive/2010/09/03/using-the-multiple-nics-of-your-file-server-running-windows-server-2008-and-2008-r2.aspx Thanks. Tiger Li TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.