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I've "Bridged" the NIC's in my Server 2003 box but when I do a large file transfer, I see that only one is active at a time.

What do I need to do to spread the love across both NIC's? I'm hoping to increase transfer speeds from my Server to my network.

PS: I have a D-Link DGS-1016D Switch.

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up vote 1 down vote accepted

To do this you need to "trunk" (also called "bonding" or "link aggregation") your two NICs. To do this you need:

  1. NICs that support this (most common are LACP or 802.3ad)
  2. An OS that supports this
  3. A switch that supports this

Windows does not support this out of the box, so you will need to use latest manufacturer drivers for your NICs, and follow their instructions for enabling this functionality.

I don't think the DGS-1016D supports link aggregation though, so you might have been struck out on the first hurdle.

The other option is to run different services on the different NICs, so if your issue is with multiple concurrent file transfers, run half over the IP address of NIC1 and half over the IP address of NIC2. This should give you a similar overall result.

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Would it also work to assign different IP's to the NIC's but assign the same DNS name (the server also runs our in-house DNS). Then enable round robin on the DNS server? – Chase Florell Apr 20 '10 at 3:49
Possibly, but it's not going to give you control over who goes where, so it's quite possible that everyone is going to end up on the same NIC. What I tend to do is give the server a 2nd entry in the DNS under a different name, which is quite useful if the server is multi-tasking. Our exchange server is also our VoIP server, so we have livexs1 and livevoip1 that both go to different NICs on the same server. – Mark Henderson Apr 20 '10 at 4:00
Our backup catalogue is also on our storage array, so we also split the traffic over two NICs for that one too, as the backup NIC is working 24/7 – Mark Henderson Apr 20 '10 at 4:01
This is a very VERY small install. I'm running a staging server and a couple of VM's for minor in house things. Nothing mission critical. I just wanted to try and distribute the load and have a bit of a fail-safe in case one NIC goes down. – Chase Florell Apr 20 '10 at 4:08
If that's the case then you can manually bridge your VMs to seperate NICs to do manual load balancing, but as a failover you'll need supported hardware down to the switch level. – Mark Henderson Apr 20 '10 at 4:12

Disclaimer: This applies to what I see in Windows and may be different for another OS.

When run in load sharing mode it's quite normal to only see one NIC in use. Only when the demand in one direction gets to the point where the second NIC is required will you see traffic flowing through it. OTOH, I quite often see inbound traffic on one NIC and outbound on the other.

Also bear in mind that the total throughput is often limited by other connected devices. e.g. A server with 2 1Gb NICs won't be bothered by a few clients connecting with 100Mb NICs. No point having a suer fast connection on the server if it can't be utilised by the clients.

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Actually my entire network is on Gigabit and I tested by transferring a 4GB file across the network. – Chase Florell Apr 20 '10 at 4:31
If one end has a single 1Gb NIC the other end can't make the transfer any faster by having more than one. The maximum speed is dictated by the slowest component involved in the transfer, whether that's a NIC, a switch/hub or something else. – John Gardeniers Apr 20 '10 at 5:53

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