From The Linux Foundation

Tuning

• TCP

Test Tools

There are a wide range of tools available for measuring network performance. Common ones are:

• NetPIPE
• Netperf
• Iperf
• gensink
• ttcp
• n-u-t-t-c-p great successor to ttcp.
• nttcp An improved version of the popular ttcp program.
• ISIC is a suite of utilities to exercise the stability of an IP Stack and its component stacks (TCP, UDP, ICMP et. al.)
• curl-loader application traffic generation (HTTP/S, FTP/S), loading and testing tool

Benchmarks

Also of interest are common network application benchmarks such as:

netbench 

Windows file server benchmark develped by Veritest and used by PC Magazine.
It has been discontinued but you can download the client here.

nfsstone 

NFS benchmark available at Gelato@UNSW

specweb 

Web server benchmark. Original SpecWeb99 is replaced by SpecWeb2005.
This is a commercial benchmark that costs $1200/$300 and has reporting restrictions.