Our servers are using at least a NIC-Team of 3 (plus an independent Management-Adapter) to balance the load and ensure availability. 

Regular client access is perfectly fine and works without interruption, but when we transfer data between the servers (backups for example) we notice a frequent "disconnect" of 1-5 seconds. 

First, all servers have been running in LCAP Mode with dynamic load-balancing. After testing a lot of configuration settings without success, we ended up having static teams with Address Hash-Based load balancing. (The idea was that the disconnect might be caused by the dynamic distribution)

However still: Every 50 seconds or so, the nic used to transfer data is dropping to a speed of "0 Bytes/second" for 1-5 seconds. Also other Clients accessing the server in question through the pooled connection then suffers from a short disconnect. (Remote desktop client, etc...)

Neither of the Servers shows an error log, nor does the NIC Teaming interface report any problems - just the "Bytes/Second" drops to 0: (In this example, nic 3 is used due to address hash)

Connection drop:

the switch used is a HP ProCurve  1810G - 24 GE, with proper setup of the static teaming on the respective ports.

the Switch reports whenever a link is up or down - and whenever the issue appears, such an event is logged: 

1	Info	Sep 11 13:23:07	NIM	Interface 6 is Link Down
2	Info	Sep 11 13:23:10	NIM	Interface 6 is Link Up

If the teaming as removed and the server are using a single connection, no problems appear, connection remains stable.

All nics have been configured with a static duplex mode to avoid effects caused by auto-negotiation.

Any idea where to start with debugging this?

Maybe I should add, that the teaming is configured on the hyperv-hosts, while the servers transfering data are vms that are hosted on seperate hyperv hosts. (the Teamed connection is exclusively assigned to the hyperv-switch used by all VMs on that certain host)

• Edited by dognose Friday, September 11, 2015 1:43 PM

Hi Dognose,

Since there were no errors or events, it is difficult to reproduce and analyze the problem.

I have seen cases that broadcom NICs caused issues of NIC teaming. Are your NICs broadcom?

If yes, try to update the latest driver. Or contact the technical support for help.

Here is the link:
https://www.broadcom.com/support

When transfering data using host, not VM, did the issue also appear?

Besides, have you tried switch independent mode?

Best Regards,

Leo