Virtual machine effects on network traffic dynamics

Although virtual machine performance has been widely studied in the context of CPU utilization, the effects of virtual machines on network traffic dynamics has received far less attention. In this study, using VMware´s GSX server on a Linux host, we evaluate the impact of VM overhead on TCP performance in both a LAN and emulated WAN environment. It is shown that when multiple VM hosted TCP senders compete on a LAN, sustained aggregate throughput decreases significantly and that ack arrival distributions are strongly affected. In the emulated WAN environment, TCP is shown to exhibit increasingly bursty behavior with associated increases in loss rate as the number of virtual Web servers increases.