The Windows Server 2003 Resource Kit includes a new tool called linkspeed, which measures the connectivity between two hosts. You run the command from one system and target a remote system:

> linkspeed /s \\<ServerName>

> linkspeed /s <ServerDNSName>

Alternatively, you can specify the /dc switch to have it test the machine’s current domain controller:

> linkspeed /dc

I’ve tested linkspeed on Windows 2000. While it runs without fatal errors, it doesn’t produce consistent results. It works best when the target system is another Windows Server 2003 machine.

Finding the link speed between two hosts is often useful when troubleshooting network connectivity problems. For example, if a client is having problems authenticating to Active Directory, you should learn the link speed between the client and the domain controller with which it is authenticating. A slow speed, perhaps due to congestion, could be the cause. If you want to determine the average link speed between two hosts, you should run the linkspeed command several times over multiple days. The results for any particular run of linkspeed could vary significantly depending on what is happening in the network at that time.