AWS, Cloud Computing

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AWS Load Balancers: A Comprehensive Comparison for Optimal Use Cases


Amazon Web Services (AWS) offers various load balancing solutions to distribute incoming traffic across multiple servers or instances. These load balancers help to maintain a high availability and fault tolerance in your application infrastructure, ensuring seamless performance even during peak demand periods.

In this blog post, we’ll dive into a detailed comparison of the various AWS load balancers, examining their features, advantages, and use cases to help you choose the right solution for your needs.

Classic Load Balancer (CLB)

The Classic Load Balancer, formerly Elastic Load Balancer (ELB), is a legacy load balancing solution that distributes incoming traffic between Amazon EC2 instances using either the round-robin or least outstanding requests algorithms.

Key Features:

  • Supports Layer 4 (TCP/SSL) and Layer 7 (HTTP/HTTPS) traffic
  • Offers sticky sessions, health checks, and CloudWatch metrics

Use Cases:

  • Simple web applications with low traffic
  • Legacy applications that do not require advanced routing features


  • Simple to set up and manage
  • Cost-effective for small-scale deployments


  • Limited routing capabilities
  • It does not support WebSocket or HTTP/2

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Application Load Balancer (ALB)

The Application Load Balancer is a Layer 7 load balancer designed to handle HTTP and HTTPS traffic. It offers advanced routing features, allowing you to distribute traffic based on content, host, or path.

Key Features:

  • Supports HTTP/HTTPS traffic
  • Advanced routing rules based on content, host, or path
  • Integration with AWS services like ECS, EKS, and Lambda
  • Offers sticky sessions, health checks, and CloudWatch metrics

Use Cases:

  • Microservices or container-based applications
  • Applications that require advanced routing rules or WebSocket support


  • Advanced routing capabilities
  • Better performance compared to CLB
  • Supports WebSocket and HTTP/2


  • Not suitable for Layer 4 (TCP/SSL) traffic
  • More expensive than CLB

Network Load Balancer (NLB)

The Network Load Balancer is a Layer 4 load balancer designed for high-performance applications that require low latency and high throughput. It operates at the connection level, making it ideal for TCP and UDP traffic.

Key Features:

  • Supports Layer 4 (TCP/UDP) traffic
  • High throughput and low latency
  • Preserves the source IP address of the client
  • Offers health checks and CloudWatch metrics

Use Cases:

  • Applications that require low-latency and high-throughput performance
  • Applications that use Layer 4 protocols (TCP/UDP)


  • High performance with low latency
  • Handles millions of requests per second
  • Suitable for high-traffic applications


  • Limited to Layer 4 traffic
  • No advanced routing capabilities like ALB

Gateway Load Balancer (GWLB)

The Gateway Load Balancer is a specialized load balancer designed for deploying, scaling, and managing third-party virtual appliances like firewalls, intrusion prevention systems, and deep packet inspection systems.

Key Features:

  • Simplifies virtual appliance deployment and scaling
  • Supports Layer 3 traffic
  • Integration with other AWS services like Transit Gateway and VPC Ingress Routing

Use Cases:

  • Deploying and managing third-party virtual appliances
  • Network infrastructure requiring advanced security and compliance features


  • Simplifies virtual appliance deployment and management
  • Supports Layer 3 traffic


  • Not suitable for general-purpose application load balancing


When choosing an AWS load balancer, evaluating your application’s specific requirements and use cases is crucial. Classic Load Balancer is best suited for simple, low traffic applications. At the same time, Application Load Balancer is ideal for microservices or container-based applications that require advanced routing rules or WebSocket support. Network Load Balancer handles low-latency, high-throughput Layer 4 traffic, making it perfect for high-traffic applications. Finally, Gateway Load Balancer is the go-to choice for deploying and managing third-party virtual appliances and advanced network infrastructure.

By comparing each load balancer’s features, advantages, and use cases, you can choose the best load balancing solution for your application infrastructure. Remember that the ideal load balancer for your needs depends on your specific requirements and the nature of your application. With the right choice, you can ensure high availability, fault tolerance, and seamless performance for your users, even during peak demand periods.

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Drop a query if you have any questions regarding AWS Load Balancer and I will get back to you quickly.

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1. Can I use multiple load balancers for a single application?

ANS: – Yes, you can use multiple load balancers to distribute traffic to different application components or achieve a higher level of redundancy and fault tolerance.

2. How do I choose between Application Load Balancer and Network Load Balancer?

ANS: – Choose Application Load Balancer for advanced Layer 7 routing features, HTTP/HTTPS traffic, and microservices or container-based applications. Opt for Network Load Balancer for high-throughput, low-latency Layer 4 traffic handling and high-traffic applications.

3. Can I switch from Classic Load Balancer to Application or Network Load Balancer?

ANS: – Yes, AWS provides a migration guide to help you transition from Classic Load Balancer to either Application Load Balancer or Network Load Balancer.

WRITTEN BY Vineet Negi

Vineet Negi is a Research Associate at CloudThat. He is part of the Kubernetes vertical and has worked on DevOps and many other Cloud Computing technologies. He is an enthusiastic individual who is passionate about exploring all the latest technologies from a learning perspective.



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