Microsoft KB Archive/283963

= Either the Windows NT Loading Balancing Service or the Network Load Balancing Computer Is Unable to Log on to the Network =

Article ID: 283963

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q283963



SYMPTOMS
In a multiple adapter configuration (two or more netcards are on the Windows NT Loading Balance Service [WLBS] or the Network Load Balancing computer), either the WLBS or the Network Load Balancing computer may not log on to the network when the other members of the cluster are functional, and you may receive the following error message:

No logon servers are available.

NOTE: Either the WLBS or the Network Load Balancing cluster computers can converge and talk to each other on their dedicated addresses.



CAUSE
This behavior can occur because the domain controller of the computer that is attempting to log in is on the same subnet as the WLBS or the Network Load Balancing adapters. This behavior can occur on an intermittent basis.



RESOLUTION
To work around this behavior, move the WLBS or the Network Load Balancing cluster to a different subnet than the domain controller.



STATUS
This behavior is by design.



MORE INFORMATION
Transmission Control Protocol/Internet Protocol (TCP/IP) cannot distinguish between the different adapters on the same subnet. This behavior means that the computer can send out packets from the Network Load Balancing adapter to talk to a domain controller on the same subnet. If this behavior occurs on a 2-node WLBS or Network Load Balancing configuration, there is a 50 percent chance that this computer is the computer that discards the packets coming back from the domain controller.

When the packets are received individually, they are not discarded and each individual computer works correctly. When the packets are received with either WLBS or Network Load Balancing disabled, the computers also work (because the packets have not been discarded).

When you attempt to trace the source of the behavior, you may determine that the WLBS or the Network Load Balancing virtual adapter is the source IP, and that the responses are from the domain controller (going to the WLBS or the Network Load Balancing adapter). The responses actually reach the client computer, and then are discarded.

If you isolate the WLBS or the Network Load Balancing cluster to its own subnet, you can work around this behavior because the default gateway (that has been set up only for the dedicated network adapter) can force all packets to go through the dedicated network adapter.

Keywords: kbclustering kbenv kbprb KB283963

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