NIC Teaming and Load Balancing question

[chuckk281]

Mark had a customer question on NIC teaming:

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I have a customer that has configured NIC teaming on his Windows 2008 R2 server and would like to see if he can also load balance across the NICs. He currently uses a tool called Spotlight on Windows for system monitoring and sees that under the Network section one NIC shows about 95% utilization, and the other NIC shows 0% utilization.

They are using the Network Configuration Utility. Are there any settings that can be changed to allow for these teamed NICs to also load balance? Or are there other areas that we can make modifications to try and balance the network traffic across the NICs?

It does appear that load balancing may take place when transmitting but not receiving. We did notice that the TEAM Type Selection options under the Teaming Controls Tab only has a selection for transmitting and not receiving. Could it be that it is only load balancing during transmit?

BTW, this server is a BL460C with VC Ethernet modules.

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Dave replied:

The basic teaming/bonding tools only use both/all NIC path in transmit. The switch returns on only one path. This is not our tool, but industry standard.

They would need to use Switch or Network teaming/bonding to utilize both directions. The key to these are, that it takes configurations on the switch to make it function. And it would be my guess that not all switches can be configured for SLB or NLB.

Ed also commented:

You may also want to investigate what type of load balancing decisions are being made by our teaming driver.

It might currently be set for MAC load balancing which might explain the 95/0 utilization.

If the NIC team is talking to a MAC address on a router then our teaming driver will assign one NIC to talk to that MAC using an internal algorithm based on the destination MAC address.

If that destination MAC address doesn’t change then the teaming driver keeps going back to that same NIC in the NIC team to transmit that traffic.

You can try changing the team to do IP Load Balancing which would be based on the destination IP address in the packet. This may give you a wider range of possibilities than a single MAC address and as such could result in a more equitable packet distribution.

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Any experiences in load balancing? Comments?