Some of my VMs (Guests) are doing advanced routing and packet manipulation (using Linux). Unfortunately, the support for "TCP Segment Offload" in the VMXNET 3 driver causes this to malfunction, as the machine needs to process the TCP packets individually, and not as preassembled TCP segments.
Under ESXi 4.0u1 I could solve this by turning off TSO in the VMXNET 3 driver using "ethtool -K ethX tso off ; ethtool -K ethX gso off", but after I upgraded to ESXi 4.1 and VMware tools 8.3.2, this no longer helps, and the VM still receives oversized pseudo-packets combined from multiple network packets, which in turn causes connections to fail.
So how do I turn off TCP Segmentation Offload for VM/vSwitch traffic under ESXi 4.1 ?
In case it matters: This is a HP DL385 G5p with on board Broadcom NICs.
i think this is not possible anymore an a vm basis since 4.1 (sadly). so my guess would be (if i am right) to either disable tso on the host or (maybe easier) to switch the virtual nic on this special vm.