In a Nutshell

Load balancing ensures the even distribution of traffic
Method ensures better performance and greater reliability, among other things
Particularly popular in data centers as well as for websites and web applications
Hardware, software and cloud solutions are available as load balancers
Algorithms decide which server processes the request

What is Load Balancing?

Load balancing is a method of distributing traffic / data traffic across a large number of servers. With the help of a load balancer, their workload is optimized and the overloading of individual servers is avoided. This ensures the availability of websites and services without delays or restrictions, even at peak times.

How do Load Balancers Work?

Load balancers are either hardware-based (server) or software-based (virtual machine / cloud). The load balancer acts as a reverse proxy in the network - all incoming requests from the internet first converge here.

The load balancer then checks which of the connected servers can process the respective request most efficiently. Depending on the algorithm used, various criteria (status / load / connections) are taken into account for this assessment. The request is then forwarded to the relevant server in the pool.

The Advantages of Load Balancing

From start-ups to SMEs to global players - the use of a load balancer is practically indispensable for companies today in order to ensure the functionality of their own web applications. The following points in particular make this method interesting for companies:

Optimized Use of Resources

Intelligent distribution of the workload across the available servers maximizes the use of resources and prevents overloads. Individual load balancers are also able to flexibly switch server resources on or off depending on the workload.

Increased Availability and Reliability

If servers fail, the load balancer distributes traffic to other servers in real time. This redirection reduces potentially expensive downtimes of individual servers to a minimum.

Improved Performance

Thanks to the even distribution of data traffic, the response times of websites / applications remain consistently low. This ensures that customers are consistently satisfied with the technical performance of the respective apps, services, etc.

Optimal Scalability

The size of the server pool to which a load balancer distributes the workload can usually be flexibly adjusted. Servers can be added or removed as required. This means that there are practically no limits to the potential growth of a business model.

Where are Load Balancers Used?

Load balancing as a method for efficient traffic distribution is present in the network worldwide today. Practically every sector and industry is dependent on stable, high-performance networks in various forms and benefits from this technology.

It is particularly widespread where companies provide digital offerings and services. The following IT applications are of particular importance:

Web Applications / Websites

Typically highly frequented websites, platforms or news portals rely on load balancing in order to be reliably available online even with a very large number of simultaneous requests. The same applies to large online stores such as Amazon, which record enormous traffic peaks, especially on special occasions (Prime Day).

Software-as-a-Service (SaaS)

For companies that offer Software-as-a-Service solutions, load balancers are absolutely essential as part of their own IT infrastructure. This is because an even distribution of requests is the only way to ensure that customers have access to the applications provided (often for a fee) at all times.

Cloud Infrastructure

Load balancing gives companies that use a cloud-based IT infrastructure the certainty that their systems are always available, even at peak load times. This means that nothing stands in the way of digital processing of all business processes - even those with a high computing load - in practice.

There is also a wealth of other areas of application, ranging from the provision of content via content delivery networks (CDN) to secure transactions in online banking and stock exchange trading.

Types of Load Balancing

Companies have the option of integrating different types of load balancers into their IT. Initially there were only hardware solutions, but now more and more software solutions and cloud-based balancers are being used. However, all variants still have their own raison d'être, depending on the intended use.

Hardware Load Balancer

An independent, physical load balancer with special software is installed at the deployment site. Its hardware is optimized and dimensioned for the specific application purpose. The use of such load balancers is particularly worthwhile in large data centers or for companies with complex network structures.

These devices are typically designed for peak loads - this makes them easy to scale initially, but depending on the intended use, the performance of the device may (still) significantly exceed the requirements at the time of installation.

Software Load Balancer

A software load balancer is usually set up in an existing server, where it takes on the function of an application delivery controller (ADC). It is often installed on a dedicated server, which itself only transfers the incoming requests to the pool.

Software-based load balancers are considered inexpensive to purchase, easy to set up and uncomplicated to scale. In contrast to hardware-based solutions, there is no need to purchase separate devices and integration into virtual IT structures is usually possible without difficulty.

Cloud-based Load Balancing

Modern software load balancers provide the basis for cloud-based load balancing. Here, the virtual infrastructure serves as the basis for virtual load balancing and an even distribution of traffic in cloud computing environments.

Balancers optimized for the cloud are usually set up in virtual machines. This variant of load balancing is particularly suitable for cloud-native applications or for companies that regularly experience large fluctuations in server load and rely on flexible scalability as required.

Load Balancing Algorithms - an Overview

Traffic is distributed to the individual servers within a pool according to specific criteria. The load balancer uses an algorithm to determine which request is forwarded to which server.

There are also two types of algorithms:

Static load balancing algorithms
Incoming data traffic is distributed according to static criteria (IP address / order of servers). The current status or state of servers is not taken into account.
Dynamic load balancing algorithms
When distributing data traffic, the current status of the servers or their utilization is taken into account. This helps to ensure optimum load distribution.

Depending on the area of application, either one or both types can be used. We have listed the most common algorithms below.

Round Robin

The load balancer assigns requests to the next active server in the pool based on a defined sequence. This procedure is very simple to implement, but important aspects such as the urgency or scope of a request and the current utilization of individual servers are not taken into account.

Weighted Round Robin

This algorithm makes it possible to assign servers a different weighting according to their capacity and performance. In the otherwise cyclical distribution of requests, individual servers are weighted more heavily according to their performance data and receive more traffic / requests accordingly.

Least Connections

Requests are forwarded to the server with the fewest currently active connections. This means that less busy servers receive more requests than those with many active connections. This helps to better distribute the workload, but can also lead to less performant servers receiving demanding requests that they may process less efficiently.

Weighted Least Connections

Load balancing is based on the weighting of a server (based on its capacity) and the utilization of a server (based on the active connections). The load balancer checks the availability and performance of the servers for each request before forwarding a request to them. This method can be very efficient, but requires an extremely precise setup.

Least Response Time

The load balancer measures the response times of the servers in the pool and assigns new requests to those with the shortest response times. These servers are weighted more heavily at the same time. This weighting can shift as a result of continuous measurements - for example, if the server is heavily loaded. This means that the requests are always distributed dynamically between the available servers in the network.

IP-Hash

The decision as to which server processes a request is based on a hash value of the client's IP address. Requests from a specific client are therefore always processed by the identical server. This is particularly advantageous when it comes to providing session-based applications - such as the content of shopping baskets in online stores. A variation of this is the source IP hash, whereby only the source IP of the client is used to generate a hash value.

Best practices - Successfully Introducing Load Balancing

Well-designed load balancing can be a great asset to your IT infrastructure. Nevertheless, there are a number of best practices that should be observed when selecting, setting up and operating load balancing to ensure its successful implementation.

1) Determining Requirements

Companies should examine in detail what the current status of their own IT is and what requirements it should fulfill in the future. Where does the company want to develop - and how does the IT infrastructure need to grow in order to achieve this goal?

2) Choice of Technology

Hardware or software - the prior analysis has a decisive influence on which load balancer solution should be selected. For companies that want to remain particularly flexible, it may be worth opting for partially or fully cloud-based load balancing right from the start.

3) Correct Configuration

Particularly in view of the large number of algorithms, it is essential that load balancers are set up correctly. This includes, for example, the weighting of servers based on their capacity and performance to match the respective algorithm - supposedly simple errors can, in the worst case, cause considerable inefficiencies at this point.

4) Redundancy and Failover

By integrating several (virtual/physical) load balancers into the system, a single point of failure is avoided. A failover (cluster) should also always be set up so that requests are processed or forwarded by a backup instance if a server - or the balancer itself - fails. At best, the effectiveness of these mechanisms should be validated regularly using suitable stress tests.

5) Monitoring and Analysis

Consistent monitoring of requests, performance and server utilization provides a good picture of whether the load balancer is functioning as desired. By monitoring important KPIs (response time, etc.), companies always stay informed and can take measures in good time if there are problems with the distribution of traffic.

Do you think that the topic of load balancing could also be relevant for your company? GFOS Cloud & IT-Infrastructures GmbH will inform you personally and individually about your options and the potential that still lies dormant in your IT. Please contact us for a no-obligation consultation.