What Is Load Balancing? How It Works?

What Is Load Balancing? How It Works?

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Updated on Feb 27, 2024 14:14 IST

Suppose an online service is facing issues, such as availability and redundancy. In that case, it can lead to a critical impact on the vendor’s reputation as well as result in a poor end-user experience. As a result, no online vendor can afford a web server overload or lag, so they use a technique known as Load Balancing to overcome this problem.

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So, what is load balancing and how it works? Before answering these questions, let’s quickly go over the topics that we will be covering in this blog:

What is load balancing? 

Load Balancing Definition: Load balancing is a technique to distribute network traffic across multiple servers in order to prevent server overload.

If we consider networking without load balancing, the results will be disastrous! Humans are evolving alongside new technology, which is evolving rapidly. When we compare ourselves to the last twenty years, we see a lot has changed. For example, most of us, particularly the younger generation, prefer to purchase goods from websites such as Amazon, Flipkart, Google, etc. What if these sites take 15-20 minutes to display the search results, or if you experience lags or downtime?

Your online experience with that website or vendor will be negative, and you might not want to use their services. Instead, you might even plan to go to the market and buy things in person. And as a result of such incidents, both the customer and the business will suffer. Hence, the need for this technique in networking is enormous!

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You can also explore: Load balancing in cloud computing

How does load balancing work? 

Load balancers are used to perform load balancing. A load balancer can be hardware- or software-based, determining which pool server can best meet a given client request in real time while ensuring that heavy network traffic does not overwhelm a single server. Thus, maximizing network capacity.

A load balancer ensures that no single server is overworked or overburdened, resulting in poor performance. If a single server fails, the load balancer diverts traffic to the leftover online servers. When a new server is added to the server group, the load balancer begins sending requests to it automatically.

Load balancers provide failover in addition to maximizing network capacity and performance. When a server fails, a load balancer immediately redirects its workloads to a backup server, reducing the impact on end users. In order to understand the working of load balancing, let’s go through the types of load balancing algorithms that play a deceptive role in the working of the load balancer.

You can also explore: OSI Model Explained: 7 Layers and Their Functions

Load Balancing Algorithms

There are mainly two types of load balancing algorithms, such as:

  • Static
  • Dynamic

Let’s go through each of them one by one:

Static load balancing algorithm

Static load balancing algorithms transfer tasks without taking the present state of a server in a server pool into account. A static load balancer is unaware of which servers are functioning slowly and are underutilized. It instead assigns workloads according to a predetermined plan. Let’s go through an example to understand the static load balancing algorithm in a better way.

Suppose there are four servers in a server pool, and there is hardware whose job is to direct tasks to these servers. Now, imagine that this hardware goes in order, assigning the first task to server 1, the second task to server 2, and so on, without looking back to see how quickly the tasks are completed. If the four servers perform efficiently, this system will work fine — but if one or more servers are lagging because of some issues, those particular servers will have a long list of pending tasks. Thus, resulting in a bad customer experience. 

Also Read: Most Asked Networking Interview Questions and Answers

The advantage of static load balancing is its ease of use and quick, simple deployment, though there are some situations (as stated in the preceding example) where this algorithm is not best suited. There are several types of the static algorithm, such as:

  • Round Robin: The Round Robin load balancing algorithm distributes traffic to a list of servers in rotation using the Domain Name System (DNS). The Round Robin algorithm uses the round-robin method to assign tasks. Initially, it chooses the first node randomly and assigns tasks in a round-robin fashion to the other nodes.
  • Weighted Round Robin: The Weighted Round Robin algorithm allows an administrator to give each server a different weight. Servers deemed capable of handling more traffic will receive a new task.
  • IP hash: The IP hash load balancing algorithm combines the source and destination IP addresses of incoming traffic and converts them into a hash using a mathematical function. The task is assigned to a specific server based on the hash.

Dynamic load balancing algorithm

Dynamic load balancing algorithms consider each server’s current availability, workload, and health before transferring a task. They can redirect traffic from overburdened or poorly performing servers to underutilized servers, ensuring even and efficient distribution. Let’s go through an example to understand the dynamic load balancing algorithm in a better way.

Suppose there are four servers in a server pool, and there is hardware whose job is to direct tasks to these servers. Now, imagine that this hardware oversees the servers, sees which servers have completed the task, how many tasks are left to be assigned, and how much approximate time it will take, etc., and assigns the tasks accordingly to these insights.

This type of algorithm provides a more efficient experience for all customers. There are several types of the dynamic algorithm, such as:

  • Least connection: The Least connect load balancing algorithm determines which servers have the fewest open connections at the time and routes traffic to those servers. This assumes that all connections require roughly the same amount of processing power.
  • Weighted response time: The weighted response time load balancing algorithm averages each server’s response time and combines it with the number of connections open on each server to determine where to send traffic. The algorithm ensures faster service for users by routing traffic to servers with the fastest response time.
  • Weighted least connection: This weighted least connection load balancing algorithm allows administrators to allocate different weights to each server, presuming that specific servers can manage more connections than others.

Benefits of load balancing 

There are many benefits of load balancing, and some of those benefits are:

Reduces wait time. Allows system administrators to handle incoming requests more easily while decreasing user wait time.

There are fewer failed or stressed components. Rather than having a single device do a lot of work, load balancing has several devices do a little work.

Improves the user experience. Users will not have to wait for a single underperforming server to complete its previous tasks. Instead, their requests are immediately routed to a more accessible resource.

Less downtime. Service providers benefit from reduced downtime and increased throughput. A complete server failure does not affect the end-user experience because the load balancer will redirect to a healthy server.

Conclusion

The load balancing technique allows the distribution of network traffic evenly in order to prevent failure caused by overburdening a specific resource. This technique boosts application, website, database, and other computing resource performance and availability. It also aids in the quick and accurate processing of user requests.

FAQs

What is load balancing?

Load balancing is a technique to distribute traffic across multiple servers in order to prevent server overload.

How many types of load balancing algorithms are there?

There are mainly two types of load balancing algorithms, such as Static and Dynamic.

What is a static load balancing algorithm?

Static load balancing algorithms transfer tasks without taking the present state of a server in a server pool into account.

What is a dynamic load balancing algorithm?

Dynamic load balancing algorithms consider each server's current availability, workload, and health before transferring a task.

Name some of the popular load balancing algorithms.

Some of the popular load balancing algorithms are: IP hash Round robin load balancing Least connection method Weighted Round Robin Least bandwidth method Hashing methods Custom load method Least response time method Weighted least connection, etc.

What is Layer 4 (L4) load balancing?

L4 load balancing operates at the transport level. L4 load balancers conduct network address translation (NAT) but do not examine each packet's content.

What is Layer 7 (L7) load balancing?

L7 load balancing operates at the application level, which is the highest in the OSI model. When deciding how to distribute requests among the server pool's servers, they can consider a broader range of data than L4 counterparts, such as HTTP headers and SSL session IDs.

Why is load balancing important?

Load balancing is critical in networking because it allows you to evenly distribute network traffic to prevent failure caused by overloading a specific resource and enhances the speed as well as the availability of applications, websites, and other computing resources.

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