Hi all, I am experimenting with virtual machines existing in the same physical machine. My configuration is:- Native: opensuse,/xen and tool used is "iperf" I am getting TCP throughput of around 8Gbps between two VM. but the UDP throughput is around 1.53 Gbps at data rate of 3000Mbps. but with this the data loss is around 20-30% I tinkered with linux kernel settings to tune the TCP sockets r|w _mem = 4096 12288 262144 r|w _ default = 12288 r\w_max = 2262144 RTT = 0.096 ms txqueuelen = 10000 backlog queue= 2000 the above setting are done in both VMs and in the Dom0. Earlier I got UDP performance of 1.8 Gbps with negligible data loss. I dont know those settings in the kernel. I am not getting the optimum settings to get around this problem. Thanking you in anticipation -- M P Singh Carleton University, Ottawa +1 613 422 8074