Experimental Setup

The experiments were performed on two Intel-based PCs that are physically connected to each other via Intel EtherExpress 100 Mb/s Ethernet NICs and a direct, crossover cable:

PC-350  - a 350 MHz Pentium II system with 128 MBytes of RAM running a Linux 2.2.13 kernel

PC-733  - a 733 MHz Pentium III system with 256 MBytes of RAM running a Linux 2.2.17 kernel.

A virtual machine is configured with a virtual AMD Lance NIC bridged to the native Intel EtherExpress NIC. The virtual machine runs a standard RedHat 6.2 Linux guest OS plus the 2.2.17-14 kernel update and uses the standard Linux pcnet32 driver to communicate over the virtual network. This virtual machine is hosted in two configurations on VMware Workstation 2.0:

VM/PC-350  - the virtual machine with 64 MBytes of RAM hosted by PC-350.

VM/PC-733  - the virtual machine with 128 MBytes of RAM hosted by PC-733.

The throughput experiments use a simple program called nettest that was developed internally for benchmarking network performance. The program opens a TCP connection between two IP addresses and copies a user specified amount of data with individual send()s and recv()s of a user specified size. The data transferred is merely repeated copies of the same in-memory buffer (to avoid paging and disk overhead) and is discarded on the receive side as soon as it arrives. The program measures the entire transfer and reports the average throughput in Mb/s.