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“A load balancer distributes incoming application traffic across multiple EC2 instances in multiple Availability Zones. This increases the fault tolerance of your applications. Elastic Load Balancing detects unhealthy instances and routes traffic only to healthy instances.”

Simplified: An ELB evenly distributes traffic between EC2 instances that are associated with it.

Basics


Pricing


Free Tier use is NOT available for ELB

  1. Each hour or partial hour the load balancer is running.
    • Region EU (London): $0.0294 per Elastic Load Balancer-hour (or partial hour)
  2. For each GB of data transferred through the load balancer.
    • Region EU (London): $0.0084 per GB of data processed by an Elastic Load Balancer

Prices may very depending on Region

Classic ELB


How to Create a Classic ELB

Basic steps

  1. In EC2 navigate to ELB.
  2. Create an ELB | Select Classic Load Balancer
  3. Basic Configuration: Give ELB a name

    If the ELB is for serving web traffic to EC2 instances, make sure ELB/instance protocol is set to HTTP and ELB port/instance port is set to 80. If you also want o add support for HTTPs, add another protocol for HTTPs traffic (port 443).

  4. Assign Security Groups:
    • Make sure that the security group you assign to the ELB has the appropriate rules set up to allow traffic based on the protocols you selected in the previous step.
  5. Configure security Settings:
    • Only applicable if you choose HTTPs as a traffic type for the ELB. In which case you need to configure additional settings.
  6. Configure Health Checks:
    • Select a ping protocol and ping port for the ELB to use to conduct health checks on the attached instances.
    • Alter Advanced Details to increase/decrease health checks thresholds.
  7. Add EC2 Instances: Select EC2 instances for ELB to serve traffic to.

    NOT required during creation; you can add instances later.

  8. Add tags

    Preferable, But NOT required.

  9. Review and Create

Sources