Throttling Bandwidth to Manage Service Availability

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Applies To: Windows Server 2003, Windows Server 2003 with SP1

If the network or Internet connection used by your Web server is also used by other services, such as e-mail or news, you can limit the bandwidth used by your Web server so that the server is available for those other services. If your Web server hosts more than one Web site, you can individually throttle the bandwidth used by each site. However, keep in mind that the IPv6 network traffic handled by your Web sites is not throttled. Bandwidth throttling uses Packet Scheduler to manage when data packets are sent.

Determining When and Where to Use Bandwidth Throttling

Before enabling bandwidth throttling, determine your Web server's typical load by using System Monitor to log the following counters over several days:

  • Bytes Total/sec or Current Bandwidth counter on the Network Interface object. To compare incoming and outgoing traffic, examine both Bytes Sent/sec and Bytes Received/sec.

  • Compare the values from the Network Interface object counters with the total bandwidth of your network connection.

If you use Performance Logs and Alerts, you can log the data to a database and then query the data, examining the results in detail.

For a typical load, your server should use no more than 50 percent of its total available bandwidth. If your server is subject to large peaks in use, keep your typical load lower than 50 percent. The remaining bandwidth can be used during peak periods.

If testing of your servers' typical loads shows that a server or a particular site is consistently using more than 50 percent of the available bandwidth, use the procedures that follow to throttle bandwidth.

In addition, before you set global bandwidth throttling, be sure that you understand the following:

  • Individual sites throttle bandwidth according to their established maximum; the global setting limits the total network bandwidth that is available for all unthrottled Web sites on a server. Setting a global WWW service maximum bandwidth does not override established bandwidth maximums for individual Web sites on the server.

  • Global bandwidth throttling settings for the WWW service do not affect FTP sites or the FTP service as a whole.

  • For more information about bandwidth throttling, including enabling packet scheduler, and enabling and disabling bandwidth throttling, see Throttling Bandwidth.