Recommendations for using AF with a hardware load balancer

If you are using a hardware load balancer with AF servers, we recommend you set up your system as follows:

• Run IIS on each AF server (this enables you to perform the HTTP status code 200 check, see Check TCP response for HTTP status code 200

• Monitor the AF Health Check PerfMon counter (for more information, see Monitor the AF Health Check counter)

• Balance traffic between the two AF servers

• Note that providing more than two AF servers can help with high availability, but does not increase scalability.

• Use a common SQL Server for the AF servers to share

For additional recommendations, see Configuration suggestions for network load balancing.

Simple network load balancing configuration

Hardware and software requirements

To support this configuration, you need to ensure that:

• Your hardware load balancer supports the configuration whereby AF server traffic flows through port 5457, and you monitor the site on a different port, for example, port 80.

• Ideally, your hardware load balancer monitors the AF Health Check on one port and if the AF service is up and running, it load balances the traffic on port 5457.

• Clients connect to AF servers by using the virtual IP address (VIP) of the hardware load balancer.

• Clients should not connect directly to AF servers without going through the load balancer, because the PIFD database will return the same AFSystemID value for each AF server, which causes errors for the AF SDK.

Failure handling

In the event of a failure, configure the following actions to occur:

• If one AF server is taken out of service, direct traffic to the other AF server.

• If the SQL Server fails, take both AF servers out of service.

• If no AF server is available, inform users that the site is down or under maintenance.