AWS (Amazon Web Services) load balancers play a key role in distributing incoming network traffic across multiple targets to improve scalability, availability, and performance.
Let’s take a simple example to clarify the concept. During the holiday rush, your online store experiences high traffic. With the right resources and setup, you might face loading speed issues or even crashes. AWS load balancers are ideal for addressing this scenario, as they distribute traffic across containers, EC2 instances, and other resources to ensure the smooth operation of the application and network.
There are different types of load balancers to suit your requirements perfectly.
- AWS – Application Load Balancer
- NLB – Network Load Balancer
- GWLB – Gateway Load Balancer (GWLB)
Let’s further understand the load balancer types in this blog.
Types of AWS Load Balancers
AWS Amazon Web Services offers four types of load balancers that aim to improve the availability and scalability of your applications. Each load balancer has its own uniqueness and features to suit your specific use cases.
1] Application Load Balancer (ALB)
The AWS Application Load Balancer (ALB) works at the application layer (Layer 7) of the OSI model. It is ideal for handling HTTP and HTTPS traffic. Here, requests are routed based on URL paths, query parameters, and more. ALB supports HTTP/2 and WebSockets, enabling the implementation of applications.
ALB includes a listener that accepts client requests. According to a set of rules, the listener directs traffic towards specified target groups. The related targets can be found in each target group, i.e., in servers or microservices.
Use case: Ideal for web apps that need HTTP/HTTPS routing.
2] Network Load Balancer (NLB)
A Network Load Balancer (NLB) works at the transport layer (Layer 4) and comes with both high performance and low latency. It distributes TCP, UDP, and TLS traffic across EC2 instances based on IP protocol and can serve millions of requests per second.
NLB is ideal for high-workload, network-intensive applications such as media streaming, gaming, and more. It supports static and elastic IP addresses, maintains client source IPs, and responds to traffic spikes effectively. Cross-zone load balancing ensures your NLB distributes traffic across all resources.
Use case: Ideal for streaming and high-performance applications.
3] Classic Load Balancer (CLB)
The Classic Load Balancer is one of the oldest, meaning a legacy load balancer within AWS services. It is mainly designed to provide basic load balancing across different Amazon EC2 instances. CLB operates at both Layer 4 for TCP traffic and Layer 7 for HTTP/HTTPS traffic in the OSI model, and distributes traffic across several EC2 instances to ensure continued availability. Even with the latest AWS load balancer options, CLB remains an ideal choice for legacy applications that need simple load balancing.
Use case: Simple and legacy applications.
4] Gateway Load Balancer (GWLB)
With the above three load balancers, AWS Application Load Balancer, Classic Load Balancer, Network Load Balancer, and the last is AWS Gateway Load Balancer (GWLB). It makes networking easy by serving as a single entry and exit point for incoming traffic, avoiding the need for multiple load balancers. It’s a layer 3 protocol in the OSI model that uses a hash of the flow in 3-tuple or 5-tuple mode and makes sessions sticky on applications.
Use case: Security firewalls.
Benefits of AWS Load Balancers
AWS Load Balancers have the following benefits.
- Auto Scaling: It helps scale automatically during traffic spikes.
- Higher Availability: Redirects traffic to healthy instances across multiple zones.
- Top-Notch Security: It uses SSL/TLS and is compatible with AWS security services.
- Fault Tolerance: This prevents downtime when a server or zone fails.
- Low Latency: Route requests for faster responses.
Final Words
We now have a clear idea of the different types of AWS load balancers. They play a key role in supporting simple to complex web applications. From the above types, you can choose one to meet the needs of your application, while getting higher availability, performance, and more. By understanding its uniqueness and features, you can unlock the full potential of the AWS load balancer.
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Frequently Asked Questions
Q1. How many types of load balancers are there?
Ans: Load balancers are divided into Virtual Appliance, Hardware Appliance, and Software Native Load Balancers.
Q2. Which load balancer is ideal for microservices?
Ans: The Application Load Balancer (ALB) is ideal for microservices as it supports path-based routing, container integration, and advanced HTTP/HTTPS features.
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