AWS Application Load Balancer (ALB) is a service that provides advanced load balancing capabilities for HTTP and HTTPS traffic at the application layer (Layer 7) of the OSI model. ALB routes incoming traffic to different targets, such as Amazon EC2 instances, ECS tasks, or Lambda functions, based on rules that you define.
AWS Elastic Load Balancing (ELB) is a service that provides load balancing capabilities for distributing incoming network traffic across multiple targets, such as Amazon EC2 instances or containers, in a single or multiple Availability Zones. ELB consists of four types of load balancers:
- Application Load Balancer (ALB): An advanced load balancing service for HTTP and HTTPS traffic at the application layer (Layer 7) of the OSI model, as I described in my previous response.
- Network Load Balancer (NLB): A high-throughput, low-latency load balancing service for TCP, UDP, and Transport Layer Security (TLS) traffic at the transport layer (Layer 4) of the OSI model.
- Classic Load Balancer (CLB): A legacy load balancing service that provides basic load balancing capabilities for HTTP, HTTPS, TCP, and SSL traffic. It has been largely superseded by ALB and NLB, but is still supported for legacy applications.
- Gateway Load Balancer(GLB): This helps to easily deploy, scale, and manage third-party virtual appliances. It gives one gateway for distributing traffic across multiple virtual appliances while scaling them up or down, based on demand
Some of the key features of ELB include:
- High availability and scalability: ELB is designed to provide high availability and scalability by automatically distributing traffic across multiple targets, and by automatically scaling up or down based on demand.
- Security: ELB helps protect against common network-based attacks, such as Distributed Denial of Service (DDoS) attacks, by automatically scaling capacity and filtering malicious traffic.
- Health checks: ELB performs health checks on targets to ensure that they are healthy and available before routing traffic to them.
- Integration with other AWS services: ELB integrates with other AWS services, such as Amazon EC2 Auto Scaling and AWS Certificate Manager, to simplify the configuration and deployment of applications.
The following are some pros and cons of using AWS Elastic Load Balancing (ELB):
- High availability and scalability: ELB automatically distributes incoming traffic across multiple targets, allowing for high availability and scalability of your application.
- Security: ELB provides built-in DDoS protection, SSL termination, and encryption of traffic between clients and targets, which helps secure your application.
- Multiple load balancer types: ELB provides three different types of load balancers, each with their own unique capabilities and features, allowing you to choose the best one for your application needs.
- Health checks: ELB performs health checks on targets to ensure they are healthy and available before routing traffic to them, improving application availability.
- Integration with other AWS services: ELB integrates with other AWS services, such as Amazon EC2 Auto Scaling, to automatically scale up or down based on demand.
- Cost: ELB can be expensive, especially if you are using the Application Load Balancer, which charges per hour and per GB of data processed.
- Learning curve: ELB has a relatively steep learning curve, especially if you are new to load balancing or AWS services in general.
- Limited customization: ELB has limited customization options compared to other load balancing solutions, which may not meet the needs of some applications.
- Limited support for non-HTTP/HTTPS traffic: While Network Load Balancer can handle other protocols, ELB is primarily designed for HTTP and HTTPS traffic, which may be a limitation for some applications.
AWS ELB is a powerful and flexible load balancing service that provides advanced routing capabilities and integrates with other AWS services to simplify the deployment and management of applications in the cloud.