Load balancing can be defined as the process of distributing a network’s traffic uniformly across multiple servers. This avoids overburdening any angle network and ensures that the workload is spread equally. Load balancing can improve the responsiveness of an app and the availability of apps and websites for users across the globe. No modern application can run fluently without load balancers, and over time, load balancing software has made the entire process highly efficient.

A load balancer may be:

  • A virtualized algorithm or instance that runs on a specialized hardware or software process.
  • Inculcated with any ADC/ application delivery controllers, which are designed to heighten performance and security of three-tier web and microservices-based applications, irrespective of which server they’re being hosted on.

Hardware Vs. Software Based Load Balancers:

There are hardware, software, and virtualized load balancers. They each differ in the way they function, perform, and the features they offer.

Hardware Load Balancers:

Hardware load balancers are usually high-performance appliances that can securely handle several gigabytes of traffic from a variety of sources. Built-in virtualization features can be included in these appliances, allowing several virtual load balancer instances to be consolidated onto the same hardware. This allows much more flexibility when it comes to full isolation of tenants and multi-tenant architectures.

Software Load balancers:

Load balancing software works in a contrasting manner to hardware balancers. These can replace hardware load balancers while delivering superior functionality and flexibility. They can run on hypervisors, containers, and even as a Linux process, all while maintaining minimal overhead on servers. They are also highly configurable and can save on storage functions.

What are some of the common load balancing algorithms?

To decide how requests are distributed around the server farm, a load balancer, or the ADC that includes it, will use an algorithm. Some of them are:

Round Robin

Round robin is a basic technique for ensuring that each client request is forwarded to a different virtual server based on a revolving list. Load balancers are simple to set up, but they don’t take into account the current load on a server. A server could become overwhelmed if it receives a large number of processor-intensive requests.

Least Connection Method

Although round-robin does not take into account a server’s current load (only its position in the rotation), the least link method does, and as a result, it typically provides better results. The least link approach instructs virtual servers to send requests to the server with the lowest number of active connections.

Least Response Time Method

The least response time method, which is more advanced than the least link method, is based on the time it takes a server to respond to a health monitoring request. The answer time is a good indication of how busy the server is and what kind of user experience to expect. The number of active connections on each server is often taken into account by certain load balancers.

Hashing Methods

This group of methods makes decisions based on a hash of data from the incoming packet. This includes link or header details from the incoming packet, such as source/destination IP address, port number, URL, or domain name.

Method of Loading Customized

The load balancer may use the custom load method to query the load on individual servers via SNMP. The administrator may specify the server load they want to query – CPU use, memory usage, and response time – and then combine them to meet their needs.

Types of Load Balancer

Numerous types of load balancing software and hardware exits, each catering to different requirements. Some of the best available ones are:

  1. Network Load Balancing: Network load balancing uses network layer data to decide where to send a network’s traffic. This is achieved by leveraging four load balancing, which can handle all types of TCP/UDP traffic. Though considered as the fastest solution, when balancing the distribution across servers, it can fall short.
  • HTTP(S) Load Balancing: This form of load balancing is one of the oldest and relies on layer 7, which means it operates in the layer of the application. It is said to be the most flexible type of load balancer as it allows a user to make distribution decisions based on the data attached with an HTTP address.
  • Internal Load Balancing: This is nearly identical to network load balancing but can be used to efficiently balance internal infrastructure as well.

Load balancing software can be installed directly into a server or can even be purchased as a service( LBaaS or Load Balancer as a Service). If you choose to purchase an LBaaS, the vendor is responsible for installing, maintaining, and running the software.