ELB

Elastic Load Balancing provides three different types of load balancers:

  • Application Load Balancers operate at layer 7 and are capable of host- and path-based routing. They have HTTP/2, WebSockets and IPv6 support. ECS dynamic port mapping is supported.
  • Network Load Balancers L4?
  • Classic Load Balancers operate at layer 4, with layer 7 awareness. They support EC2-Classic, non-HTTP TCP and SSL listeners and have support for sticky sessions using application-generated cookies.

DNS

All ELB instances are given a randomly generated hostname under <region>.elb.amazonaws.com, providing a stable name for CNAMEs that can be used across AZs.

Cross-zone load balancing

Cross-zone load balancing allows you to define the traffic split across AZs.

load balancer nodes scale relative to demand, but we only see a single logical resource

Logs

Once enabled, access logs are written to objects named:

s3://<bucket>[/<prefix>]/AWSLogs/<account id>/elasticloadbalancing/<region>/<yyyy>/<mm>/<dd>/<account id>_elasticloadbalancing_<region>_<alb id>_<end time>_<ip address>_<random>.log.gz

The log entries include information about both the request and response action.

Timing

Timing information is split across three metrics:

  • request_processing_time contains the total elapsed time, to ms precision, from receipt of the request until dispatch to a target.
  • target_processing_time contains the total elapsed time, to ms precision, from dispatch to a target until the target began sending response headers.
  • response_processing_time contains the total elapsed time, to ms precision, from the target's delivery of headers to the load balancer beginning delivery to the client.

Children
  1. ALB
  2. Classic
  3. NLB

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