Paper: VMware vSphere 4.1 Networking Performance

VMware recently published an in-depth analysis about the latest vSphere network performance. The paper, downloadable here without any registration, goes into details explaining how VMware handles various high load benchmarks under various operating systems and configurations.

Performance of VMs communicating among each other and with systems outside the hosts are measured and correlated with the processing power (number of vCPUs) and NICs, showing the scalability results.
Interesting facts: throughput compared to 3.5 seems to have increased ten times, and a single VM can generate so much traffic to saturate a physical 10Gbs interface all by itself.