Layer 7

From LB Wiki

Aslo referred to as the application layer, layer 7 refers to the 7th layer of the OSI model, which is the application layer. In the OSI model, there are seven layers: Physical, data link, network, transport, session, presentation, and application.

When talking about load balancers and Layer 7, this means a load balancer that is operating at the application protocol level. The most common application that load balancers work with is HTTP.

In load balancing, Layers 5 through 7 are combined and referred to as simply Layer 7.

Performance Considerations

Load balancers operate in one of two modes: Layer 4 or Layer 7. Layer 4 is not faster than Layer 7, in that users won't notice faster response times. However, a load balancer is typically capable of serving up a higher rate of Layer 4 connections than it is Layer 7 connections, simply because with Layer 7 there is more work involved.

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