How load balancers route requests
Load balancers forward data packets in the same manner as Network Address Translation (NAT) devices. The packets are forwarded at the TCP level with modified address information to the target system.
To distribute client requests across each group of BMC Remedy AR System servers, the load balancer can use various scheduling policies. The following two policies are the most common:
- Round Robin — This policy directs client requests to each BMC Remedy AR System server, one at a time. Successive requests are routed to the next BMC Remedy AR System server, then the next, and this process is repeated consecutively.
- Least Connections — This policy directs client requests to the BMC Remedy AR System server that has the fewest connections.
For better throughput, most load balancers offer multiple network ports. This method avoids collisions between the incoming and outgoing routed network traffic.
The load balancer also offers clients the ability to stick to one target system. This means that all requests from a single client are routed to the same system.
For versions 7.6.04 or later, BMC recommends configuring the load balancer that is located between the web servers and BMC Remedy AR System servers without setting a "sticky" bit. In versions earlier than 7.6.04, BMC recommended setting the sticky bit to activate session affinity to route all connections from one web server to the same BMC Remedy AR System server. For more information, see Scenarios for load balancing between the web servers and BMC Remedy AR System servers.
If you use other BMC products that also support load balancing without setting the "sticky" bit, make sure your BMC Remedy AR System server and other BMC product(s) use the same version. For example, BMC Atrium CMDB supports configuring the load balancer without setting a "sticky" bit for version 7.6.04 Service Pack 1 or later, and does not support it for version 7.6.04. If you configure load balancing without setting a "sticky" bit for both of these products, your BMC Remedy AR System server must also use the matching 7.6.04 SP1 or later version.