What is Classic Load Balancer ?
Tags: aws
Published: 2023-06-20 06:18:36

In AWS (Amazon Web Services), Classic Load Balancer (CLB) is a load balancing service that distributes incoming network traffic across multiple Amazon EC2 instances. It helps improve the availability, scalability, and fault tolerance of applications by evenly distributing the workload among instances.

**Here are some key points about Classic Load Balancer in AWS:**

**1. Traffic Distribution:** Classic Load Balancer evenly distributes incoming traffic across multiple EC2 instances or Availability Zones to ensure optimal resource utilization. It balances the load based on various algorithms, including round-robin, least connections, and IP hash, depending on the configuration.

**2. High Availability:** CLB enhances the availability of applications by automatically detecting unhealthy instances and routing traffic only to the healthy instances. If an instance fails or becomes unreachable, CLB directs traffic to the remaining healthy instances, maintaining uninterrupted service.

**3. Elasticity and Scalability:** Classic Load Balancer enables automatic scaling of application capacity. As the demand for the application increases, additional instances can be added to the load balancer to handle the increased workload. Conversely, when demand decreases, instances can be removed to optimize resource utilization and cost.

**4. SSL Termination:** CLB provides SSL termination, allowing it to handle HTTPS traffic by decrypting SSL/TLS requests from clients and forwarding them to instances using HTTP. This offloads the SSL/TLS decryption workload from the instances, improving performance and reducing the computational load on backend servers.

**5. Health Checks:** Classic Load Balancer regularly performs health checks on registered instances to ensure that they are operating properly and can handle incoming requests. If an instance fails the health check, CLB stops routing traffic to that instance until it passes the health check again.

**6. Cross-Zone Load Balancing:** CLB offers Cross-Zone Load Balancing, which evenly distributes traffic across multiple Availability Zones. This feature helps ensure that the traffic is efficiently distributed among instances in all available zones, enhancing the fault tolerance and scalability of the application.

**7. Integration with AWS Services:** Classic Load Balancer integrates with other AWS services, such as Auto Scaling, Amazon CloudWatch, and AWS Certificate Manager. This integration allows for automated scaling based on traffic patterns, monitoring of load balancer metrics, and management of SSL/TLS certificates.

**8. IPv6 Support:** CLB supports IPv6, enabling applications to handle incoming IPv6 traffic seamlessly. It provides IPv6 addresses to EC2 instances and can load balance traffic over IPv6.

It's important to note that Classic Load Balancer is the predecessor to Application Load Balancer (ALB) and Network Load Balancer (NLB) in AWS. While Classic Load Balancer continues to be supported, ALB and NLB offer additional features and capabilities that are better suited for modern application architectures. By obtaining [AWS Cloud Certification](https://www.edureka.co/masters-program/aws-cloud-certification-training), you can advance your career in AWS. With this course, you can demonstrate your expertise in AWS, developing and maintaining AWS-based applications, and building CI-CD pipelines, many more fundamental concepts, and many more critical concepts among others

Classic Load Balancer in AWS provides an essential component for ensuring high availability, scalability, and efficient distribution of traffic across multiple EC2 instances. It contributes to improved performance, fault tolerance, and seamless handling of incoming network traffic for applications deployed in AWS.