Dual NICs for niftier networking

ANALYSIS The Priority setting helps determine which host takes over if one of those in the cluster fails. The settings range from 1 to the number of hosts in the cluster, with 1 being the highest priority. Depending on the port rules, the host with the highest priority handles all of the default traffic for the cluster, and if it fails, the host with the next highest priority assumes the role. The port rules, however, have a lot of say in how traffic to the cluster is routed. The Initial Cluster State parameter determines whether NLB should start with Windows and whether the host joins the cluster. The Dedicated IP Address is the host's unique IP address used for traffic not associated with the cluster. Mike pointed out that the port rules setup is a key NLB feature, giving you control over how each port's cluster traffic is handled. "For example, you can set traffic rules that say if the primary server has no [active] connections, connect the primary, but if it has one connection, route to the next available server." This ensures that the workload for each server in the cluster is manageable. These traffic-handling rules are configured in the Port Rules tab, shown in Figure D. You can set a port range for the rules and select the protocol governed by the rule.
The Multiple Hosts setting specifies that more than one host in the cluster will handle traffic associated with this port rule. In Mike's case, the application he needs to balance is set for a particular port, so he set up a port rule that essentially shares the workload for the app across all the servers in the cluster. The Affinity parameter is another setting that can significantly affect performance. You can set the affinity to Single to prevent double logons, keeping the server from being overloaded. The Load Weight parameter lets you distribute the workload according to the processing power of the servers in the cluster. If the servers are roughly the same, you can just select Equal. Good news for the end user
The result of the setup Mike has established for the application running on the server cluster is that the end users see shorter response times and higher availability. The multiple NICs improve throughput to and from the application servers while also providing failover. In this case, the application is a critical component to the work performed at Mike's company, so using the dual NIC setup coupled with Win2K's NLB ensures that the application will nearly always be available and that it performs well for the users. If you're looking for ways to maximize throughput on your network and provide failover, installing multiple NICs in your servers is a good solution. Depending on the hardware and software installed on your network, a number of options are available, including Cisco's Fast EtherChannel, IP Metrics' NIC Express software, and the NLB service available in Win2K Advanced Server. Other vendors may offer similar solutions, so you should check with your hardware manufacturer to find out what options are available to you.

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