AWS Elastic Load Balancing – why is it important?

Content Writer
DevOps Engineer

Web applications are often subject to a fair amount of traffic fluctuation. During the pre-Christmas period, during promotions, or while running intensive advertising activities, more customers are expected to visit e-commerce sites. However, this phenomenon is also seen in apps from other industries, such as ed-tech or fintech.

In such situations, flexible scaling of resources in the cloud is paramount. By expecting more visitors, we can increase the number of allocated processors and the amount of memory and, during downtime periods, reduce them to cut costs. Load balancing is a great feature that allows applications to be monitored and automatically adjusts performance to maintain consistent, predictable performance at the lowest possible price. Furthermore, it allows you to automatically scale resources (servers, database, storage, etc.) up or down based on a predefined threshold for metrics such as memory usage, network usage, and CPU usage.

This article focuses on the types of flexible application scaling and the main advantages of such solutions. But let’s begin with a definition of AWS Elastic Load Balancing.

What is the AWS load balancer?

In Amazon Web Services (AWS), Elastic Load Balancing acts as a load balancing service, scaling system performance in response to changes in incoming traffic. This is important as modern applications need to process millions of users simultaneously and send each correct user text, videos, images, and other data quickly and reliably. Most applications incorporate multiple server resources with duplicate data to handle the high traffic volume. An overloaded server leads to slowdowns, timeouts, and improperly handled or lost requests, negatively affecting the customer experience.

The load balancing system acts as an invisible intermediary, ensuring equal utilization of all server resources. It automatically distributes incoming traffic to different targets, such as EC2 instances, containers, or IP addresses. Moreover, it monitors the health of its registered marks, directing traffic solely to healthy targets. ELB helps the IT team adjust performance based on the application and scale of network traffic.

How does Elastic Load Balancer work?

Elastic Load Balancer (ELB) automatically scales load balancing systems and applications based on real-time traffic. It automatically routes incoming application traffic to instances and acts as a point of contact for incoming traffic. Furthermore, it uses system health checks to find application servers, properly route traffic to available servers, and manage a failover for high availability or capacity expansion purposes.

ELB detects servers in lousy shape, prevents traffic from being sent to them, and then distributes the load to the remaining targets in good condition. It provides integrated certificate management and SSL (Secure Sockets Layer) decryption, enabling flexible centralized management of SSL settings, including offloading the CPU-loaded application.

Which ELB system to choose?

Elastic Load Balancing offers four types of load-balancing systems. Choosing the right option lets users spread different tasks across resources, resulting in process optimization and increasing application responsiveness, scalability, and availability while reducing the risk of traffic congestion (i.e., increased fault tolerance). 

Load balancing systems operate according to a preset algorithm of varying complexity. This determines the distribution of requests between servers.

ALB (Application Load Balancer) – Load balancing module

Layer 7 (HTTP/HTTPS traffic) – flexible

ALB operates at the application layer or the seventh layer of the OSI (Open Systems Interconnections) model. It controls communications between multiple systems, identifying traffic in order of priority and directing it to registered targets in good standing. For example, URLs marked with the /API extension can be directed to suitable application resources, while traffic associated with /MOBILE can be guided to mobile access management resources.

This type of load balancing is a new generation from AWS that handles multiple requests in a single connection. The HTTP/2 protocol reduces network traffic.

AWS users can apply ALB through internal load balancing against AWS EC2 instances, applications (via Rest API), or containers. ALB can also be combined with other AWS services to optimize application availability and scalability. These services can include AWS Certificate Manager, Amazon EC2, Amazon Route 53, AWS WAF, and Amazon CloudWatch.

NLB (Net Load Balancer) – Network load balancing system

Layer 4 (TLS/TCP/UDP traffic) – static IP addresses

NLB in AWS distributes end-user traffic across multiple cloud resources, yielding low latency and high throughput for applications. Its goal is to equalize traffic load support for elastic or dynamic IP addresses. It can handle millions of end-user requests per second and unpredictable spikes in end-user traffic.

The NLB system performs health checks on so-called “targets” – an EC2 instance, an IP address, or a container, among others – to ensure it is directing traffic to a high-performance resource. If this is not the case and the target becomes unavailable, the network load balancing module directs traffic to another target.

GLB (Gateway Load Balancer) – Gateway load balancing system

Layer 3 (TCP/UDP traffic)

The GLB system facilitates the installation, administration, and monitoring of virtual devices, including intrusion detection and prevention systems, firewalls, and deep packet inspection systems. It combines a network gateway and distributes traffic. You can scale your virtual appliances (up or down) according to your specific requirements by using a single gateway to distribute traffic to multiple destinations. With fewer potential failures, the reliability of your network increases.

CLB (Classic Load Balancer) – Classic load balancing module

Layer 4/7 (HTTP/TCP/SSL traffic)

AWS CLB, or Classic Load Balancer, is a connection-based balancing system where requests are passed through the load balancing system without initially being “analyzed.” They are merely forwarded to the back-end section. CLB is recommended only for EC2 instances. Its main functions are OSI Layer 4 or Layer 7 load balancing, SSL offloading, and IPv6 support. It does not support host-based and path-based routing. Once configured, the load balancer distributes the load between servers regardless of what is on the server, which can reduce performance in certain situations.

AWS load balancer benefits

ELB balances the load by routing and controlling Internet traffic between application servers and their guests or clients. Additionally, it distributes loads among multiple computing resources, such as virtual servers. It checks their status and directs traffic to those units that can handle requests enough to ensure scalability and service availability. Using ELB’s cloud auto-scaling module increases application, availability and resiliency increase.

Below we look at the four main benefits of this feature.

1. Maximum scalability

ELB can handle huge traffic spikes and thousands of requests simultaneously, enabling it to support high throughput. It allows you to manage incoming traffic in one or multiple availability zones without disrupting traffic flow. Additionally, ELB systems can be used intelligently to direct network traffic between multiple servers. This involves foreseeing application traffic so that different servers can be added or removed. Furthermore, load balancing prevents traffic bottlenecks on any server and facilitates scaling.

2. Total adaptability

The load balancing module protects the web application from service interruptions and increases systems resilience by detecting server problems and redirecting client traffic to available resources. By configuring health checks that monitor resource health, the load balancing module recognizes which path is in good shape and which is not.

3. Security and Monitoring

ELB provides access to AWS CloudWatch monitoring, analysis, and request tracking, enabling real-time application performance assessment. This increases the ability to see how applications behave, revealing performance issues and application stack problems on special requests. Above all, it allows you to increase data protection and prevent data loss. This is an important feature, especially when the flow contains sensitive data.

Load balancing systems can also do the following:

  • Monitor traffic and block malicious content
  • Automatically redirect attack-related traffic to multiple back-end servers
  • Conduct traffic routing through a group of firewalls
  • Perform analysis of physical and virtual computing resources

4. Performance

Load-balancing modules improve application performance by increasing response times and reducing network latency. They perform several critical tasks, such as:

  • Equal distribution of load between servers
  • Redirect client requests to a geographically closer server to reduce latency
  • Ensure the reliability of operations

How can Studio Software help monitor and manage AWS flexible load balancing modules?

In this article, you’ve learned basic information about the load balancers used on AWS. Which one you use in your application – concerning, for example, end-to-end SSL/TLS encryption, path-based routing, or host-based routing – will determine the type of load-balancing system that is best for you.

Load balancing is crucial for scaling, ensuring security, and performing health checks on servers, making it an ideal choice for enterprises.

Please reach out to our team of experts if you want to learn more about how to get started with an application load-balancing solution that will benefit your business.

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