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AWS Load Balancers: The Types, Use Cases, and Benefits

Originally Published February, 2024 · Last Updated July, 2024

Have you ever wrestled with managing high traffic on your website or app? 

For example, let’s say customers swamp your online store during a big sale. Without the right setup, you might face slow load times or, even worse, a total crash

An AWS load balancer is perfect for these scenarios. It spreads your traffic across multiple targets like Amazon EC2 instances and containers, ensuring everything runs smoothly. 

With different types available—like the Gateway, Application, and Network load balancers—there’s a solution for every need. 

Below, we’ll introduce AWS load balancers and explain what they are, the types available, their benefits, and various use cases. By the time you’re done reading, you’ll know how to use them to streamline your AWS experience. 

What is an AWS load balancer?

An AWS load balancer directs traffic, steering client requests across all servers capable of fulfilling those requests. This process maximizes speed and capacity use. 

A load balancer makes sure a single server doesn’t bear too much demand. 

By spreading requests evenly, AWS load balancers make sure individual servers aren’t overloaded, helping with cost optimization and keeping your application running smoothly.

There are a few types of AWS load balancers:

  • Classic Load Balancer (CLB): Suitable for simple load balancing of traffic across multiple EC2 instances
  • Application Load Balancer (ALB): Best for load balancing of HTTP and HTTPS traffic, providing advanced request routing targeted at delivery of modern application architectures
  • Network Load Balancer (NLB): Ideal for handling millions of requests per second while maintaining ultra-low latencies
  • Gateway Load Balancer (GLB): Helps deploy, scale, and manage virtual appliances, such as firewalls and intrusion detection and prevention systems

Your AWS load balancer continuously checks the health of its registered targets and only routes traffic to the operational ones. 

Plus, with listeners and rules, you have the flexibility to direct traffic based on the URL path or the port number.

This service operates across multiple Availability Zones. Your load balancer automatically assists with fault tolerance, distributing incoming application or network traffic across multiple targets, such as EC2 instances, containers, and IP addresses.

The choice of protocol, like HTTP, HTTPS, TCP, or SSL protocols, depends on your specific needs. Elastic Load Balancing auto-scales with the incoming traffic to help your applications run smoothly.

With AWS handling the heavy lifting, you can focus on what’s important—building your applications.

Types of AWS load balancers

Amazon Web Services offers different types of load balancers that can improve the scalability and availability of your applications. 

Each type serves specific use cases, from routing HTTP/HTTPS traffic to handling high-performance network connections.

Application Load Balancer (ALB)

An Application Load Balancer excels at managing HTTP and HTTPS traffic, providing advanced request routing to services running on AWS. 

ALB enables path-based routing and supports HTTP/2 and WebSockets, allowing you to implement modern application architectures. ALBs manage this process through listeners, rules, and target groups that route the incoming traffic to the appropriate targets.

Network Load Balancer (NLB)

For scenarios where high performance and low latency are critical, a Network Load Balancer is your go-to option. 

NLBs handle millions of requests per second, operating at the connection level—Layer 4 (TCP/UDP). They can handle volatile traffic patterns while providing one static IP address per Availability Zone for simplicity. 

Features like cross-zone load balancing ensure your NLB can distribute traffic efficiently across all available resources.

Gateway Load Balancer (GWLB)

A Gateway Load Balancer can deploy, scale, and manage your virtual appliances such as firewalls or intrusion detection systems. 

GWLBs seamlessly distribute traffic to these appliances, enhancing security and reliability without compromising on performance. They use a GENEVE-based interface to interconnect with the appliances and work directly with Elastic Load Balancing.

Classic Load Balancer (CLB)

The Classic Load Balancer is the legacy option within AWS load balancing services.

It provides basic load balancing across multiple Amazon EC2 instances. It operates at both the request level—Layer 7, mainly for HTTP/HTTPS traffic—and the connection level—Layer 4, primarily for TCP traffic. 

While CLBs can manage SSL security, they aren’t as feature-rich in terms of routing capabilities as newer offerings.

ALB vs. ELB: What’s the difference?

When you’re deciding between an Application Load Balancer (ALB) and an Elastic Load Balancer (ELB) in AWS, you need to understand the main differences to ensure optimal performance for your applications.

Elastic Load Balancer (ELB)

  • Traffic distribution: Equally across all EC2 instances
  • Routing rules: Less advanced; primarily operates at Layer 4 (Transport Layer)
  • Use-case: Ideal for simpler load balancing of applications running on one or more Amazon EC2 instances

Application Load Balancer (ALB)

  • Traffic distribution: Context-aware, routes traffic based on content
  • Routing rules: Sophisticated, application-level (Layer 7) routing, such as URL path or hostname
  • Use-case: Suited for advanced routing needs, as well as handling microservices and container-based applications

Elastic Load Balancing (ELB), which includes both ALB and Classic ELB, is a service that automatically distributes incoming application traffic across multiple targets. 

The right choice between ALB and ELB depends on the specific requirements of your application.

When it comes to performance, an ALB can handle sudden and unpredictable traffic patterns while also providing extensive monitoring capabilities. With ALB, you get the flexibility to route traffic based on complex rules that you define, allowing for a more fine-tuned user experience.

In your decision, consider how your application is structured. For straightforward setups where a robust routing mechanism isn’t required, a Classic ELB might suffice. However, for modern architectures, particularly those requiring application-specific routing and load balancing (such as microservices), the ALB is the more suitable option.

Use cases for load balancers

Load balancers are vital for optimizing the performance, reliability, and scalability of your applications. 

Whether you’re deploying web applications, distributing global traffic, or ensuring fault tolerance, a properly configured load balancer plays a pivotal role.

Web application deployment

Your web application can benefit greatly from an Application Load Balancer (ALB), which uses advanced routing rules to manage HTTP and HTTPS traffic. By distributing incoming requests across multiple Amazon EC2 instances, ALBs improve your application’s responsiveness and availability.

Global traffic distribution

A Network Load Balancer (NLB) efficiently handles global traffic distribution by routing requests to the closest Availability Zones. This process ensures low-latency performance and high throughput for your users across the globe.

Microservices architecture

Aligning with a microservices architecture, ALBs support dynamic service discovery, which allows applications to adapt to the changing number of microservices. This approach optimizes your application’s efficiency by rerouting traffic based on the most current service deployments.

Auto Scaling groups

Auto Scaling groups work in tandem with load balancers to manage fluctuations in traffic. By automatically scaling your EC2 instances up or down, your application maintains consistent performance during demand spikes or lulls.

Containerized applications

For containerized applications, particularly those orchestrated using Amazon Elastic Container Service (ECS), ALBs facilitate smooth operation by providing flexible routing and load balancing across containers. They enhance your infrastructure’s overall resilience and flexibility.

Application health monitoring

Regular health checks of targets are crucial. Load balancers constantly evaluate the health of connected instances, rerouting traffic away from unhealthy ones to maintain uninterrupted service and prevent potential downtime.

Domain name resolution

Managing DNS names and directing client requests to the best endpoint, ALBs and NLBs ensure efficient domain name resolution. They route user traffic by translating human-readable domain names into the IP addresses of EC2 instances.

Disaster recovery

In scenarios requiring fault tolerance and high availability, load balancers are essential for disaster recovery strategies. They distribute traffic across multiple data centers, ensuring a single point of failure doesn’t compromise your application’s accessibility.

Benefits of load balancers

Load balancers ensure your web applications remain online and also perform under high-traffic situations. 

By distributing the workload across several computing resources, like EC2 instances, load balancers maintain performance and reliability. Here you’ll find why incorporating load balancers into your infrastructure is crucial for modern web applications.

Improved reliability and availability

You need high availability and fault tolerance to maintain an uninterrupted service. 

Load balancers create health checks on servers to route traffic only to the operational ones. This process means if one server fails, the load balancer seamlessly redirects traffic to maintain service continuity. 

Elastic Load Balancing across Availability Zones further bolsters reliability, ensuring there’s no single point of failure.

Scalability

As demand fluctuates, your system must easily adapt. Auto Scaling in conjunction with Elastic Load Balancing can adjust the resources you use based on actual traffic. This adjustment could mean spinning up more EC2 instances during peak times and reducing capacity when demand wanes. 

Application Load Balancers and Network Load Balancers play a pivotal role in handling variable loads, ensuring scalability without loss of performance.

Traffic management

Effective traffic management is crucial for optimal application functioning. Load balancers, by using various routing rules, distribute traffic efficiently. 

This process might involve directing traffic to servers that host specific parts of an application or using an Application Load Balancer for complex request routing based on the content type or behavior.

Flexibility and efficiency

Finally, load balancers offer unmatched flexibility and efficiency. You can define rules for how it should handle traffic, which can range from simple round-robin schemes to more sophisticated content-based routing. 

Classic Load Balancers, Network Load Balancers, and Application Load Balancers cater to different needs, from simple load balancing for a single application to managing highly complex systems with numerous simultaneous targets.

AWS services that have native integration with ELB

Amazon Elastic Load Balancing (ELB) distributes incoming application traffic across multiple targets, ensuring high availability and reliability of your applications. When you configure and deploy ELB, you’ll find seamless integration with a range of AWS services. 

For instance, Amazon ECS integrates directly with ELB, allowing you to route traffic efficiently to your ECS services. This combination helps manage containerized applications that require dynamic load balancing based on current demands.

AWS Certificate Manager (ACM) works hand in hand with ELB, offering a simplified process to manage SSL/TLS certificates. This integration enables secure communication between your clients and services, thanks to encryption-in-transit capabilities.

Amazon Route 53 is another service that complements ELB. 

By using Route 53 for DNS management, you can direct users to a healthy load balancer endpoint, improving the availability and performance of your applications. 

Moreover, ELB benefits from the added security layer provided by AWS WAF. You can attach a web application firewall to your load balancer, protecting your applications from common web exploits.

The integration also offers:

  • Containerized services: Amazon ECS
  • SSL/TLS management: AWS Certificate Manager
  • DNS routing: Amazon Route 53
  • Application security: AWS WAF

For tutorials and more details on how elastic load balancing incorporates these services to enhance your application architecture, refer to the comprehensive guide on Elastic Load Balancing.

Optimize your AWS costs and processes with ProsperOps

When managing AWS resources, controlling costs while ensuring effective cloud operations is a delicate balance. 

ELB plays a crucial role in optimizing the performance and availability of your applications. However, it’s just as important to optimize the costs associated with these resources.

ProsperOps introduces efficiency to this process through automated cost optimization for your AWS use. By applying advanced algorithms, it adjusts your AWS discounts like Savings Plans and Reserved Instances to align with your actual use.

Leveraging ProsperOps can lead to substantial savings, whether it’s through leveraging chargeback models or removing the manual complexity from AWS cost management

By addressing the need for cost-efficient cloud services, we can help you maximize value from your investment in AWS infrastructure.

If you’re looking to streamline your cloud costs, schedule a demo today and learn how ProsperOps can benefit your business.

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