SMS: Netspeed.com Internals (131011)

SUMMARY

When you run Smsls.bat/CMD from a logon script, the Netspeed program is used to determine if the link is above a predefined threshold of speed in bits per second (bps). The results of this comparison are returned to Smsls.bat/CMD for evaluation, using MS-DOS errorlevels.

Depending upon the threshold speed set in the registry and the policy set in the Administrator tool, Smsls.bat/CMD will prompt the user to see if he or she wants inventory performed when a slow link is detected.

MORE INFORMATION

The following are possible errorlevel values:

0 - Network is fast.
1 - Network is slow, avoid further operation.
2 - Network is slow, prompt the user.

The speed threshold is defined in the HKEY_LOCAL_MACHINE\ subtree under the following key:

   SOFTWARE\Microsoft\SMS\Components\SMS_MAINTENANCE_MANAGER

The DWORD setting is Slow Net Threshold Speed. The default is 0x352 (850 decimal).

You cannot use the Administrator tool to change this setting; you must change it manually if you do not want to use the default value. If you do change it, Maintenance Manager updates Netspeed.com in SMS_SHR during the next polling interval. If Systems Management Server is not configured to automatically update user logon scripts, you must manually copy the updated Netspeed.com to the location where Smsls.bat is being run from.

A total of 3,400 bytes are read from Netspeed.dat on the logon server. The speed is measured in the number of milliseconds to read the total bytes. The default of 3,400 bytes within 850 milliseconds indicates a fast link. If it takes 850 milliseconds or longer, it is considered a slow link.

You can display the errorlevel value with the command NETSPEED /V at a command prompt.

You can use the same method to approximate appropriate modem speed: multiply 3,400 bytes by 8 bits per byte. These 27,200 bits read within 850 milliseconds will be a fast link (this is roughly 31,280 bits per second), making most 28.8 modems the minimum fast network scenario.

The documentation incorrectly states a default value of 500 milliseconds; the correct default value is 850 milliseconds.