Microsoft KB Archive/262926

= INFO: Application Center Cluster Members Must Have Two Network Cards When Used With NLB =

Article ID: 262926

Article Last Modified on 3/10/2004

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APPLIES TO


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

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This article was previously published under Q262926



SUMMARY
All Application Center 2000 cluster members in a cluster that is using network load balancing (NLB) should have two network cards.



MORE INFORMATION
Each cluster member in a cluster that is using NLB requires a management network interface card (NIC) for the backend network for intracluster communication. The communication over this network includes cluster administration and replication. These tasks require a guaranteed and uninterrupted network for remote procedure call (RPC) communication. Because one of the replicated items is NLB settings, the frontend load-balanced NIC would not be reliable for this communication during NLB configuration of that NIC itself.

Also, when you are using NLB with Application Center, the default mode is unicast mode. Unicast mode uses the same media access control (MAC) address for the load-balanced NIC on each node. If there were only one NIC on each computer, the computers would not be able to communicate with each other over this NIC, since all traffic bound for another computer would be looped back.

Microsoft strongly recommends that you separate the frontend and backend networks for both performance and security reasons.

Keywords: kbinfo KB262926

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