With the addition of burst handling features in Windows 2000, WINS servers can now support high-volume—or "burst"—server loads. In these situations, many WINS clients actively seek to register their names with their local WINS server at the same time. In burst mode, the WINS server responds positively to clients that submit registration requests before the WINS server has processed and physically entered these updates in the WINS server database.
Burst mode uses a burst queue size as a threshold value to determine how many requests to process normally before enabling burst mode handling. By default, the burst queue allows 500 requests before a WINS server engages burst handling. For more information about changing the burst queue size, see "Configuring Burst Mode Support" in this chapter.
The burst queue allows WINS to handle intermittent periods of heavy registration and refresh traffic, such as when the WINS server is either started with a clean database or when many WINS clients come online for the first time. Either situation creates a large number of requests for registration and refreshment of names.
The function of burst handling is to answer requests superficially (with a positive response), therefore decreasing the load on the network. Burst handling also extends and varies the delay interval to distribute the load over time.
Burst handling is enabled for any WINS server running Windows NT Server 4.0 with the current service pack, as well as with Windows 2000 Server. A WINS server that supports burst handling initiates burst handling once the number of WINS client registration requests exceeds the burst queue size.
How Burst Handling Works
With burst handling, additional client requests beyond the burst queue size are immediately answered with a positive response from the WINS server. The response also includes a varying delay interval or a Time to Live (TTL) interval to help regulate the client registration load and handling of requests received in a single burst period.
Including a delay interval in the success responses lowers the rate at which new WINS clients attempt to refresh and retry name registration, and it regulates the burst of WINS client traffic.
For each additional round of 100 client requests, the delay interval is incremented by the WINS server by an additional 5 minutes until the delay interval reaches a maximum of 50 total minutes. If WINS client traffic is still arriving at burst levels once the delay interval reaches its maximum, the WINS server answers the next round of 100 client requests with the initial delay interval value of 5 minutes, and the incrementing process begins again.
For example, if the default burst queue size of 500 entries is used, the WINS server replies normally to the first 500 requests. It replies immediately to the next 100 WINS client registration requests by sending early success responses. Those early success responses use a starting delay interval value of 5 minutes.
The WINS server continues to handle burst-level request traffic in this manner until the server reaches its maximum intake level of 25,000 name registration and refresh queries. At this point, the WINS server begins dropping queries.
Configuring Burst Mode Support
You can change the level of burst mode support or disable it by using the WINS Services Properties dialog box from the WINS server. To reach this interface, open Control Panel, double-click Administrative Tools , then choose Computer Management and open the Services and Applications section. In this section, click WINS , and then, on the Action menu, click Properties . To further configure or disable burst mode support where desired, click Advanced .
Four buttons are available for configuring burst mode: Low , Medium , High , and Custom . Custom allows you to enter a number of queries from 50 to 5,000. Low , Medium , and High configure burst queue sizes of 300, 500, and 1,000, respectively.
By default, burst handling is enabled, and the burst queue is sized to Medium.
To modify burst handling
In the console tree in MMC, click the name of the WINS server for which you want to modify burst handling properties.
On the Action menu, click Properties .
Click the Advanced tab.
In Enable burst handling , modify default settings as needed.
To view a description of a dialog box item, right-click the item, and then click What's This?
Windows 2000 supports clustering of WINS servers. However, before simply adding WINS service to a set of clustered servers, be sure to consider both the advantages and disadvantages of doing so. In many cases, where the overall number of WINS servers is small, clustering WINS is simply not necessary—replication makes WINS fault tolerant. Instead, configure your WINS clients with the address of a secondary WINS server to ensure uninterrupted service.
To add WINS to a cluster
Be sure the WINS service is installed and started on both servers.
Right-click in the resources dialog box and, on the menu that appears, click New Resource .
Click Next , and choose the group you want to add.
Choose the possible owners—that is, the other members of the cluster.
Set the dependencies for the resource: the disk, the IP address, and the network name.
Type the path to the backup database, and click Finish .
Be sure that the owner to which you add WINS service has a disk, an IP address, and a name resource. Also, the database path must end with a backslash ( \ )and specify a location on the dependent disk that you select. For example, if the dependent disk is drive G, you must choose a database path on drive G.
To test that the clustering is working correctly, bring the dependent disk online (it begins offline), then right-click on the window and move the group to the other node. Groups will show the drive as a resource that can be moved; the drive is moved from one node to the next with the group to which it belongs. You should see the entry in the Owner category change as the resource moves.
For more information about clustering using Network Load Balancing, see "Network Load Balancing" in the Windows 2000 Server Resource Kit Distributed Systems Guide .
If you choose to cluster your WINS servers, be sure to equip those servers with a hard disk with high-speed I/O that is dedicated to WINS service. This helps speed up the database response, and ensures that clustering efficiency is high.