Introduction AWS Elastic Load Balancing and EC2 Auto Scaling

AWS Elastic Load Balancer – ELB

Elastic Load Balancer allows the incoming traffic to be distributed automatically across multiple healthy EC2 instances. 

 

Types of Elastic load Balancer: 

 

Application Load Balancer 

Network Load Balancer 

Gateway Load Balancer 

Classic Load Balancer

 

 

 

 

 

 

 

Application Load Balancer

• Application Load Balancer are best suited for load balancing of HTTP and HTTPS Traffic.
• Application Load Balancer performs based on layer 7 OSI model.
• It supports host-based and path-based routing. 

Note: Choose an Application Load Balancer when you need a flexible feature set for your applications with HTTP and HTTPS traffic. Operating at the request level, Application Load Balancers provide advanced routing and visibility features targeted at application architectures, including microservices and containers.

Network Load Balancer

• Network load balancers are best suited for load balancing of TCP traffic where extreme performance is required.
• Network Load Balancer performs based on layer 4 OSI model.
• It can manage a massive amount of traffic and is suitable for managing low latencies.
• Static IP address can be provided by a network load Balancer 1 per subnet.

 

Note: Choose a Network Load Balancer when you need ultra-high performance, TLS offloading at scale, centralized certificate deployment, support for UDP, and static IP addresses for your applications. Operating at the connection level, Network Load Balancers are capable of handling millions of requests per second securely while maintaining ultra-low latencies.

Gateway Load Balancer

Gateway Load Balancer helps you easily deploy, scale, and manage your third-party virtual appliances. It gives you one gateway for distributing traffic across multiple virtual appliances while scaling them up or down, based on demand.

Note: Choose a Gateway Load Balancer when you need to deploy and manage a fleet of third-party virtual appliances that support GENEVE. These appliances enable you to improve security, compliance, and policy controls.

 

Troubleshoot your Application Load Balancers:

The load Balancer generates an HTTP error 

Errors – 4** Client side error - problem with the client request and identify the problem and fix the request and retry

• HTTP 400: Bad request E.g the header is malformed
• HTTP 401: Unauthorized - user access denied
• HTTP 403: Forbidden – request is blocked by WAF access control list
• HTTP 405: Method not allowed
• HTTP 408: Request timeout
• HTTP 413: Payload too large
• HTTP 414: URI too long
• HTTP 460 - client closed connection before the load balancer could respond, client timeout period may be too short
• HTTP 463 - The load balancer received an X-Forwarded-For request header with too many IP addresses. The upper limit for IP addresses is 30.

 
Errors – server side, 5** - server side error - identify and fix the problem with your webserver / application / database / load balancer

• HTTP 500: Internal server error
• HTTP 501: Not implemented
• HTTP 502: Bad gateway
• HTTP 503: Service unavailable

 

• HTTP 504: Gateway timeout 
• HTTP 505: Version not supported 
• HTTP 561: Unauthorized