Components of a load balancer

At it’s most basic, load balancing is made up of three components:

• Pools: Which contain one or more endpoints.
• Endpoints: Which respond to individual requests.
• A load balancer: Which decides which traffic goes to each pool.

How it works

Normally, requests to your application would go to individual servers directly.

With a load balancer, requests first go through the load balancer. Your load balancer then routes requests to specific pools.

    flowchart LR
      accTitle: Load balancing flow
      accDescr: Load balancing involves a load balancer, pools, endpoints, monitors, and health monitors.
      B[Request 1] --> A
      C[Request 2] --> A
      D[Request 3] --> A
      A[Load balancer] -- Request 1 --> P1
      A -- Request 2 --> P2
      A -- Request 3 --> P3
      subgraph P1 [Pool 1]
      Endpoint1((Endpoint 1))
      Endpoint2((Endpoint 2))
      end
      subgraph P2 [Pool 2]
      Endpoint3((Endpoint 3))
      Endpoint4((Endpoint 4))
      end
      subgraph P3 [Pool 3]
      Endpoint5((Endpoint 5))
      Endpoint6((Endpoint 6))
      end

Within each pool, requests then go to individual endpoints. And that endpoint is what responds to the request.

    flowchart LR
      accTitle: Pool traffic flow
      accDescr: When an incoming request reaches a pool, it then goes to an endpoint within the pool.
    A[Request 1] --Routed by pool--> Endpoint2
      subgraph P1 [Pool]
        Endpoint1((Endpoint 1))
        Endpoint2((Endpoint 2))
      end

This progression of load balancer —> pool —> endpoint is the core part of how a load balancer works.