1 Reply Latest reply on Aug 25, 2010 6:16 AM by joergriether

    How do I disable TSO (TCP Segment Offload) on ESXi 4.1

    jbWiseMo Novice


      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.