| Event Id | 21269 |
| Source | Microsoft Firewall |
| Description | ISA NLB setup fails. ISA services show stopped due to local problem. ISA alert console indicates no suitable network adapter availible. |
| Event Information | According to Microsoft: NLB provides high availability and scalability of servers using a cluster of up to 31 host computers working together. Clients access the cluster using either an Internet Protocol (IP) address or a set of addresses. The clients are unable to distinguish the cluster from a single server. Server applications do not identify that they are running in a cluster. However, an NLB cluster differs significantly from a single host running a single server application because it can provide uninterrupted service even if a cluster host fails. The cluster can also respond more quickly to client requests than a single host. NLB delivers high availability by redirecting incoming network traffic to working cluster hosts if a host fails or is offline. Existing connections to an offline host are lost, but the services remain available. In most cases, client software automatically retries the failed connections, and the clients experience a delay of only a few seconds in receiving a response. NLB delivers scaled performance by distributing the incoming network traffic among one or more virtual IP addresses (the cluster IP addresses) assigned to the NLB cluster. The hosts in the cluster then concurrently respond to different client requests. |
| Reference Links | Network Load Balancing in ISA Server 2004 Enterprise Edition Network Load Balancing: Frequently Asked Questions for Windows 2000 and Windows Server 2003 |
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