Elastic Load Balancing

  1. Elastic Load Balancing
  2. 1. Overview
  3. 2. ELB Types
  4. 3. Network Load Balancer
    1. 3.1 NLB Overview
    2. 3.2 How to create one NLB via Console?
    3. 3.3 Concepts

Elastic Load Balancing

1. Overview

  • What is ELB?

    • ELB distributes your incoming traffic across multiple targets, such as EC2 instances, containers, and IP addresses, in one or more AZs
    • It monitors the health of its registered targets, and routes traffic to the healthy targets
    • Elastic Load Balancing help scale your load balancer as your incoming traffic change over time — automatically scale to the vast majority of workloads
  • Benefits

    • Increase the availability and fault tolerance
    • You could configure health checks, thus ELB monitor the health of the compute resources, LB only send requests to the healthy ones
  • How it works

    • Listener
      • configure your LB to accept incoming traffic by specifying one or more listeners
      • a process that checks for connection requests
        • with a protocol
        • port number
    • cross zone load balancing
      • we should enable it cause it could make sure traffic is well distributed
      • when client send request, it will first go through route 53, and route 53 will distribute traffic thus each lb node receives 50% of traffic (2 LB nodes in total )
    • request routing
      • client — amazon dns service — return IP address to client side — client use the ip address to make call to LB
      • dns entry specify the TTL to 60 seconds, this ensure that the IP addresses can be remapped quickly in response to changing traffic

2. ELB Types


3. Network Load Balancer

3.1 NLB Overview

  • Similar to ELB overview, NLB has listener
    • a listener checks for connection requests from clients, using the protocol and port number you configure, and then forwards requests to a target group
  • you can configure your health checks on a per target group basis
  • Health checks are performed on all targets registered to a target group that is specified in a listener rule for your load balancer.
  • functions at 4th layer of OSI, capable of handling millions of requests per second
    • when receives a connection request, it selects a target from the target group for the default rule
    • attempts to open a TCP connection to the selected target on the port specified in the listener configuration

3.2 How to create one NLB via Console?

  • Create a target group
    • set target type, name, protocol, port number, health check method
  • Configure load balancer and listener
    • Network mapping
      • select the VPC that you used for your EC2 instances
      • select AZ and then select public subnet for the AZ

3.3 Concepts

  • Listener
    • A listener is a process that checks for connection requests, using the protocol and port that you configure. The rules that you define for a listener determine how the load balancer routes requests to the targets in one or more target groups.
  • Target Groups
    • Each target group is used to route requests to one or more registered targets. When you create a listener, you specify a target group for its default action. Traffic is forwarded to the target group specified in the listener rule. You can create different target groups for different types of requests

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文章标题:Elastic Load Balancing


本文作者:Leilei Chen

发布时间:2021-03-09, 12:59:23

最后更新:2021-03-09, 13:00:46


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