AWS Load Balancing refers to the services provided by Amazon Web Services (AWS) that distribute incoming application or network traffic across multiple targets, such as Amazon EC2 instances, containers, IP addresses, and Lambda functions. This helps ensure high availability and reliability by spreading the workload and preventing any single resource from becoming a bottleneck. AWS offers several load balancing services, each designed to handle different types of traffic and use cases:
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Elastic Load Balancing (ELB): This is the primary load balancing service on AWS, which includes several types of load balancers:
- Application Load Balancer (ALB): Operates at the application layer (OSI model Layer 7). It is ideal for HTTP and HTTPS traffic and provides advanced routing features based on request content, such as URL path or host-based routing.
- Network Load Balancer (NLB): Operates at the transport layer (OSI model Layer 4). It is designed for high-performance and low-latency traffic, handling millions of requests per second. It is suitable for TCP, UDP, and TLS traffic.
- Gateway Load Balancer (GWLB): Designed to deploy, scale, and manage third-party virtual appliances, such as firewalls, intrusion detection and prevention systems, and deep packet inspection systems. It provides transparent bump-in-the-wire (Layer 3) load balancing.
- Classic Load Balancer (CLB): The original ELB, supporting both HTTP/HTTPS and TCP traffic. It operates at both the application and transport layers but has been largely superseded by ALB and NLB for new applications.
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Key Features of AWS Load Balancing Services:
- High Availability: Distributes traffic across multiple targets in multiple Availability Zones (AZs) to ensure application resilience.
- Scalability: Automatically scales to handle changes in traffic, ensuring consistent performance under varying load conditions.
- Health Checks: Monitors the health of registered targets and only routes traffic to healthy instances.
- Security: Integrates with AWS Identity and Access Management (IAM), AWS Certificate Manager (ACM), and supports Secure Sockets Layer (SSL) termination.
- Sticky Sessions: Supports session persistence (also known as sticky sessions) to ensure requests from a client are sent to the same target.
- Flexible Target Management: Easily add or remove targets from the load balancer without disrupting the overall traffic flow.
- Logging and Monitoring: Integration with Amazon CloudWatch, AWS CloudTrail, and access logs for monitoring and auditing traffic.
AWS Load Balancing is a critical component for building robust and scalable applications on AWS, ensuring that applications remain available and performant even under heavy traffic conditions.
