Elastic Load Balancing Introduction

Elastic Load Balancing

A Load Balancer is used to distribute application traffic across multiple EC2 Instance. The Load Balancing Service can be Client own Virtual Load balancer on EC2 Instance or can Leverage AWS Cloud Service called Elastic Load Balancing Service.

Elastic Load Balancing is a Managed Service, which Scales in an out automatically to meet increased application traffic demands. Elastic load Balancing is Highly Available with in a Region and also distribute traffic across healthy instances in multiple Availability Zones.

Elastic Load Balancing Service can be easily integrated to Auto-Scaling Service, which helps to scale EC2 instance behind the load balancer.

Elastic Load Balancing supports routing and Load Balancing of HTTP, HTTPS, TCP, TLS Traffic to EC2 Instances. Elastic Load Balancing supports TLS1.2, TLS1.1, TLS1.0, SSL3.0.

Elastic Load Balancing Service supports health checks for EC2 instances, and make sure that no traffic is routed to unhealthy or failing instances. It also supports Integrated Certificate Management and SSL termination.

Type of load Balancer

Below is different type of Load Balancer

• Classic Load Balancer
• Application Load balancer
• Network Load Balancer

Below is the overall summery of all supported features of all above three load Balancer mentioned.

Classic Load Balancer:

It distributes incoming application traffic across multiple EC2 Instances in multiple Availability Zones. Health Monitors is used to check the health of EC2 instances, so that Load Balancer can send traffic to healthy nodes only.

Classic Load balancing is used to pass TCP traffic or is used to handle HTTP/HTTPS requests and also perform SSL termination and insert HTTP proxy headers.

Classic Load Balancer are used to distribute traffic across EC2 Classic Targets also.

Below is the Architecture of Classic Load Balancer.

Application Load balancer:

Application Load Balancer operates at application layer (Layer 7). Once traffic is received, LB evaluates the Listener rules in priority order to determine which rule to apply, then select appropriate target from a target groups using round robin Algo.