Load balancing layer

ISAM supports load balancing at layer 4 or layer 7 of the Open Systems Interconnection (OSI) network model.

For each service, we can configure either of the following load balancing layers:

TCP Layer (Layer 4)

At this layer, the load balancer can use the TCP header information to determine how to process the request.

Application Layer (Layer 7)

At this layer, the load balancer can recognize application requests (for example, HTTP requests) and process these requests accordingly. The appliance load balancer does not support HTTP/2 at Layer 7.

Layer 7 offers the following extra features when compared to layer 4 load balancing:

• Ability to use an HTTP cookie to provide stickiness. For information, see Persistence.
• Ability to use and manipulate the headers in HTTP requests and responses. For information, see Benefits of layer 7 load balancing.

If we do not require these features, use layer 4 load balancing. Layer 4 load balancing is the most efficient type of load balancing. Layer 7 load balancers incur extra processing costs as they need to complete the following extra tasks:

• SSL termination.
• HTTP packet inspection.
• HTTP header manipulation (as required).

For information about configuring the load balancing layer, see Configure front-end load balancer.

Parent topic: Front-end load balancer