Hi all,

I am working with a strange problem at the minute with HP's NIC Teaming with Transmision Load Balancing.

We have a HP blade system the Server is connected to 2 cisco 3020's and then those 2 switches are connected to a 3750 Stack consisting of 2 Members.

Theres an LACP ether channel consisting of 4 Gigabit Ethernet Ports to each 3020 from the 3750 Stack.

They both have exactly the same configuration and all ports are up and the channel looks healthy.

When setting the Preference order on the server if I set the NIC connected to the 1st Cisco 3020 as primary i.e. Tx/Rx then everything is fine.

If I set the NIC Connected to the 2nd Cisco 3020 as primary then all seems fine i.e. I can ping it, it can access services outside its own vlan and the internet. It cannot however ping anything connected to the same subnet and VLAN on the 3750 Stack.

Doing a packet capture on a server connected to the VLAN on the 3750 stack I can see the Echo Requests coming in and the server sending an echo Reply but the echo reply never gets back to the server with the teamed NICs.

I did a Layer 2 traceroute and all looked fine, all the MAC Tables were good.

I thought maybe it was a layer 2 loop causing the problems but I have checked and re-checked STP and can't find any problems.

STP has picked up one intentional loop and blocked it.

I've raised a ticket with HP to see if they can point me in the right direction but I don't think it is a problem with there Drivers. It definately seems like a networking problem.

Can anyone give me any ideas on what to have a look at next.

Thanks.