The Classic Load Balancer routes traffic based on application or network level information and is ideal for simple load balancing of traffic across multiple EC2 instances where high availability, automatic scaling, and robust security are required. For applications needing advanced routing capabilities, microservices, or container-based architectures, we recommend the Application load balancer.
You can distribute incoming traffic across your Amazon EC2 instances in a single Availability Zone or multiple Availability Zones. The Classic Load Balancer automatically scales its request handling capacity in response to incoming application traffic.
The Classic Load Balancer can detect the health of Amazon EC2 instances. When it detects unhealthy Amazon EC2 instances, it no longer routes traffic to those instances and spreads the load across the remaining healthy instances.
When using Virtual Private Cloud (VPC), you can create and manage security groups associated with Classic Load Balancers to provide additional networking and security options. You can also create a Classic Load Balancer without public IP addresses to serve as an internal (non-internet-facing) load balancer.
Classic Load Balancers support SSL termination, including offloading SSL decryption from application instances, centralized management of SSL certificates, and encryption to back-end instances with optional public key authentication.
Flexible cipher support allows you to control the ciphers and protocols the load balancer presents to clients.
Classic Load Balancers support the ability to stick user sessions to specific EC2 instances using cookies. Traffic will be routed to the same instances as the user continues to access your application.
Classic Load Balancers support the use of both the Internet Protocol version 4 and 6 (IPv4 and IPv6). IPv6 support is currently unavailable for use in VPC.
Layer 4 or Layer 7 Load Balancing
You can load balance HTTP/HTTPS applications and use layer 7-specific features, such as X-Forwarded and sticky sessions. You can also use strict layer 4 load balancing for applications that rely purely on the TCP protocol.
Classic Load Balancer metrics such as request count and request latency are reported by Amazon CloudWatch.
Use the Access Logs feature to record all requests sent to your load balancer, and store the logs in Amazon S3 for later analysis. The logs are useful for diagnosing application failures and analyzing web traffic.
You can use AWS CloudTrail to record classic load balancer API calls for your account and deliver log files. The API call history enables you to perform security analysis, resource change tracking, and compliance auditing.
- IPv6 support is currently available in the following Amazon EC2 regions: US East (Northern Virginia), US West (Northern California), US West (Oregon), EU (Ireland), Asia Pacific (Tokyo), and Asia Pacific (Singapore).
- IPv6 support is currently unavailable for use in VPC.
- You can create up to twenty (20) load balancers per region which includes both Classic and Application Load Balancers. Should you need to exceed these limits, please complete this form.