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I am looking after this network with around 40 clients on one Windows 2008 R2 server. These clients are connected to server via two gigabit switches (24-port dumb switches). Over the next few months the number of clients are going to increase. Let us say we want to plan for up to 100 clients.

The network traffic is already high and sometimes it gets really clogged. My goal is to double the network bandwidth in near future and quadruple the same when we procure a new server hardware.

Obviously, this would require multiple NIC or an NIC card with multiple ethernet ports. These are my thoughts about options/limitations:

  1. I read that Windows Server 2012 has built-in NIC teaming feature. However, this is not at all viable as the licensing cost (server + CAL) would be too high. Besides, this cannot be a reason to upgrade the server software at all.

  2. Go with multiple NIC without LACP/teaming. Each NIC will have to be on a separate subnet because Windows Server does not play nicely when two of its NICs are on same subnet. Each NIC will connect to a different switch and accordingly those clients will be on different subnets. While this will increase the total bandwidth of the server, it will also add some complexities in network configuration (routing, DHCP, DNS, firewall, etc.) Can you convince me otherwise?

  3. Discard the existing dumb switches and go for something better. Netgear offers "unmanaged plus" switches which feature LACP/LAG. Each 24-port switch (highest port configuration) costs around Rs. 20k (~US$350) in India so four such switches will set us back by around Rs. 80k (~US$1400). But I think it would still be better than replacing Windows Server itself. This can be sort of last resort.

  4. I read that certain server-grade NIC cards (such as those from Intel) can offer driver-based teaming/aggregation even if the server OS or the switch don't support that feature. I have done some search and most results are about Linux and FreeNAS etc. so I am not sure if this works in Windows environment. If this is really a workable option, it is my best bet in near future. Can anyone share their experience with this kind of setup and suggest any specific NIC model to go with?

Other than that, I can try for some kind of network optimization. Currently all clients are connected to the switch directly. What I can do is introduce some small switches among a group of clients and connect those small switches to the main switches. But not sure if that will work for me because the traffic is mostly real and all of it involves the server. There isn't much going on between clients. The server is mainly being used as a file server.

What are your thoughts? Am I missing something here?

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First question:
What are the measured metrics used to determine your utilization (ie: what's "high" and "clogged"? I'm assuming this was done on the server only as you can't pull stats from unmanaged switches.

Second:

  • I would stay away from multiple nics on different subnets on the server.
  • I would stay far away from the "introduce some small switches" option
  • I would definitely upgrade the switches. I would also recommend against NetGear switches. Most of the unmanaged switches and the Netgear "enterprise switches" have limited buffer and still suffer from performance issues
  • Most modern NIC's in the server space can do some form of network teaming/bonding based on the drivers software suite. Almost all of them work fine in Windows. BACS (Broadcom Advanced Control Suite) and the Intel ACS (Advanced Network Services) are two of the more common ones).

edit to reply to your comment below as my reply was too long for a comment:

My question was trying to determine why you assume your network utilization is "already high" and "clogged". If your real problem is a design flaw (network loops, etc), a configuration issue (speed/duplex mismatches, etc), or an issue with the switches (buffer overruns/dropped packets/etc) then providing more bandwidth to the server won't help you. With your current hardware, it's hard to narrow down specifically where your issue is.

Where did you run your trace from? A wireshark trace that you say show nothing unusual isn't proof your "network traffic" is already high or getting "clogged". And not to be too harsh, but do you know what you are looking for in the trace? Based on your question and your current line of thinking, I don't know where your knowledge level is on troubleshooting a network trace to see if there are problems.

Running perfmon counters on the server NIC would give you a better picture of the utilization on the server NIC and would be only the first indication that more bandwidth to the server might be helpful. But you haven't said if you have run those counters or not.

Lastly, most driver software can do some form of network teaming with just about any switch (including unmanaged swtiches). Generally, you are limited to straight failover or transmit load balancing only. Failover is just as it sounds. Only one NIC is used until a failure is detected then it fails over to the other NIC. Transmit load balancing will only load balance outbound traffic from the system. Incoming traffic is still generally limited to a single NIC. I believe Broadcom can do SLB (Smart Load Balancing) where it attempts to do limited receive load balancing through gratuitous ARP's but I've never used it much. Full LaCP aggregation will require the switch to support it. There's more to it than all this, but this isn't a question on NIC teaming types and support.

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  • Used wireshark to inspect traffic; found nothing unusual. Copying 400mb file from server to client takes 15+ minutes - during normal operations - tested on different clients. Symantec might be an issue but not sure. The nic you mentioned, can they do teaming/aggregation without any support at switch? Your question seems to suggest that the problem might be elsewhere. Perhaps I am trying to brute force my way out. Where should I look? How? – Golmaal Jun 18 '14 at 15:36
  • Ran wireshark on server esp to see if some malware or any other activity were generating unwanted traffic. Also used netmon as initially I suspected too many ldap requests coming from firewall was an issue but that is now ruled out. In fact I never suspected it to be a network hardware/config issue as things were working alright. I believed it was gradual increase in number of clients and some sql server applications that we started using recently. My network troubleshooting experience is indeed limited; no offense taken there. will perform checks before reaching any decision. Thx. – Golmaal Jun 18 '14 at 17:33

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