【Table of contents】

1. 1. Overview
2. 2. What is ALB?
3. 3. Difference between ALB and ELB
   • a) Benefits of moving from an ELB to an ALB
4. 4. Differences between ALB, NLB, CLB and ELB
5. 5. Conclusion

• 1. Overview

  For web services, a system with a load balancer role is essential.
  By learning what kind of load balancers are available in AWS and what kind of benefits you can get from implementing them, you will be able to understand the appeal of AWS more.
  There are several types of load balancers in AWS, such as ALB and ELB, so you may get confused about which one to use.
  In this article, we will check the difference between ALB and ELB and the contents of the service.
  If you are planning to use AWS, let's understand the features of each of them by referring to this page.

• 2. What is ALB?

  The ALB (Application Load Balancer) is a part of the system called AWS (Amazon Web Services) provided by Amazon.com and is a load balancing service that distributes the load generated by web services.
  In recent years, due to the spread of social networking services and other factors, there has been an increase in the sudden concentration of access to web applications.
  A sudden spike in access will cause the web service to slow down and cause errors.
  A load balancer like ALB distributes the load on such web services and improves their stability and high availability.
  With the many features of the ALB, you will be able to run your web services continuously and effectively.

  There are many benefits to AWS services, but the following are particularly beneficial for ALB.

  ・ Supports high availability
  ・ Security, such as certificate management and user authentication.
  ・ Flexible response to application load at various levels
  ・ Close monitoring and auditing of applications

  These benefits can lead to increased efficiency and practicality in the operation of complex web services.
  The benefits will be even greater in the future, as every business can be improved and new work can be taken forward.

• 3. Difference between ALB and ELB

  When using ALBs in AWS, the term ELB is often used together.
  ELB stands for "Elastic Load Balancing" and originally this ELB was the load balancing service in AWS.
  Later, however, when ALB was developed as an additional option, ELB changed its name to "Classic Load Balancer (CLB)".
  Then, ELB came to be used as a generic term for the services of ALB and CLB.
  And now the Network Load Balancer (NLB) has been added, and its contents are further enriched.
  In other words, ELB is a generic term for AWS load balancing services that have three types of attractive load balancers: ALB, CLB, and NLB.

  Compared to CLBs, ALBs are more distinctive in many ways and have their own unique appeal.
  For example, the following points are characteristic of ALB.

  ・ Operation in Layer 7 (Application Layer)
  Older ELBs acted as load balancers, both in the transport layer at layer 4 and the application layer at layer 7.
  Layer 4 balances the load without scrutinizing the contents of the network packets, and Layer 7 balances the load more efficiently by accessing information such as HTTP and HTTPS in the packets.

  On the other hand, ALB is a load balancer that only works with Layer 7, and unlike ELB, it has a style that specializes in the application layer.
  This has allowed for the implementation and addition of more useful and easy-to-use features and increased overall support.

  ・ Supports WebSocket and HTTP/2
  The ALB now supports two new protocols, WebSocket and HTTP/2, which expands the user's choice.
  By supporting each communication standard, network traffic can be reduced and connections can be used more efficiently.

  ・ Targets the latest application architectures
  When using the ALBs, you can configure them for the latest application architectures, such as micro services and containers.
  It provides advanced request routing, so you'll be able to use it more freely and smoothly.

  ・ Can route to target groups
  An ALB can tie instances to different groups of servers, called target groups, and configure routing.
  Unlike ELBs, which are directly instantiated, services can be run independently and multiple routing rule definitions can be created.

  • a) Benefits of moving from an ELB to an ALB

    There are several advantages to migrating from ELBs to ALBs.
    In particular, the following benefits may be reasons to consider making the transition

    ・ Reduces costs by consolidating multiple load balancers
    ・ Improve efficiency by improving performance with WebSocket /HTTP2 etc.
    ・ Enhanced security through the use of AWS WAF

    In addition, it has many advantages such as adding information to the access log, saving it in a compressed form, and registering Lambda functions. Depending on the environment, it may make more sense to migrate to ALB than to stay with ELB.

• 4. Differences between ALB, NLB, CLB and ELB

  Unlike ALBs and CLBs with the above characteristics, NLBs are also load balancers with their own unique appeal.
  The Network Load Balancer (NLB) is a load balancer model that is ideal for load balancing in high performance environments.
  It can handle millions of requests per second with low latency, and is optimized for use even when traffic patterns are sudden or change quickly.
  Because of these characteristics, the NLB will also become an indispensable part of the ELB.

  While the ALB, CLB and NLB have established their own distinctiveness through various differences, the fee structure is basically unified with a system in which you are billed only for what you use.
  The hourly execution time is used as a reference, and the amount of ALB and NLB charged is determined by the amount of load balancer capacity unit (LCU) used.
  CLB also uses the hourly execution time as a reference, but the amount charged is determined in GB units according to the data transferred through the load balancer.
  As you can see, there are some differences, so you should check the details of each one carefully when you use it.

• 5. Conclusion

  In AWS, ELB is one of the services that we want to use effectively.
  Let's start by understanding the difference between ALBs and ELBs and decide which one to use in order to get your business off the ground.

  The ALB, CLB and NLB have a lot of unique appeal.
  We recommend that you take this opportunity to check out the details so that you can put them to good use.