Microsoft KB Archive/266453

= FIX: Changing NLB Load Weight Terminates Existing Connections =

Article ID: 266453

Article Last Modified on 6/4/2003

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APPLIES TO


 * Microsoft Application Center 2000 Standard Edition, when used with:
 * Microsoft Windows 2000 Standard Edition
 * Microsoft Windows DNA, when used with:
 * Microsoft Windows 2000 Standard Edition

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This article was previously published under Q266453



SYMPTOMS
When you are using network load balancing (NLB) for load balancing on an Application Center cluster and you change the load weight for any cluster member, the NLB service will terminate any existing connections to that member. This may cause client applications to fail.



CAUSE
A change in the NLB load weight causes NLB to terminate any existing Internet Protocol (IP) connections over the NLB-bound network interface card.



RESOLUTION
Microsoft recommends that you change NLB load weight when the cluster member is offline and not receiving any connection requests.



STATUS
This behavior was fixed in Windows 2000 Service Pack 2. Even with the fix in place, however, NLB only preserves the current TCP connections on the server and the cluster must still reconverge to redistribute the load according to the new loads. If your Web sites depend on session state stored on the server, such as if they use ASP session state, some clients may lose their sessions when their next TCP connection is rebalanced to a new server. Changing the load balancing weight has the same effect on sessions as adding a new sever to the NLB cluster.

Keywords: kbbug kbfix KB266453

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