A load balancer is a critical piece of technology that helps distribute network traffic to multiple servers in a way that ensures no single server has to bear an oversized load. Picture it a bit like a traffic cop, directing vehicles to make sure that traffic flows smoothly.
Load balancers are an essential piece of technology in a world in which websites that experience high volumes of traffic may be dealing with thousands or even millions of simultaneous requests from users wanting to read text, see images, and, in some cases, watch video and access application data in a timely fashion. This even spreading of network traffic is therefore necessary to improve the responsiveness of applications and make sure that these applications and websites are optimally available to the greatest number of users.
There is not a one-size-fits-all solution when it comes to load balancing. There are a range of algorithms and techniques that can be used to do the job efficiently. Below are some of the most popular algorithms used for the crucial job of efficient load balancing.
In round robin load balancing, client or user requests are distributed to application servers in a rotation. This is one of the most widely used load balancing algorithms. It works by assuming application servers are all the same, with identical availability, compute power and load handling abilities. It’s a simple, straightforward method of distributing client requests if you have a group of servers — with client requests forward, in turn, to each server. When it reaches the end of the list, the algorithm returns to the top and begins all over again.
Weighted Round Robin
A slightly more complex version of round robin load balancing, the weighted round robin approach factors in different characteristics on the part of the application server. That means that if server number one is far more powerful than number two, and number two more powerful than number three, each will be given a weight for more optimal balancing.
This dynamic load balancing algorithm distributes connections so that the pool member managing the smallest number of open connections at any given time receives the new connection request. The purpose of this approach is to ensure that no one server in a pool of servers receives a significantly larger number of active connections than other servers in the pool.
Weighted Least Connection
A slightly more complex version of the least connection algorithm, weighted least connection lets the administrator give an individual weight to every application server. This is based on its abilities to handle traffic.
Least Time Response
When you’re choosing a cashier at the supermarket, you go to the line that’s moving the quickest. That’s, in essence, what the least time response algorithm does for load balancing. Servers are selected based on the quickest response time, so that server number one responding in one second will be prioritized over server number two, which responds in two seconds. In this way it’s similar to, but distinct from, the least connections method.
There are a number of different hashing algorithms which dictate how requests are forwarded based on a particular hash value — whether that’s destination URL, destination iP address, source IP, a hash of the client’s IP address and port, and more. Hashing load bearing is useful for environments in which a cache is serving a range of content from the internet and/or various specified origin servers.
No one-size-fits-all solution
Each algorithm has its pluses and minuses (which is why there are multiple algorithms instead of just one agreed-upon method). Much depends upon your requirements when it comes to load balancing. For example, the round robin approach ensures that every target receives an entirely even split of traffic, while also being easy to understand and decipher. However, it requires that all targets exhibit similar performance and are of roughly the same size. Requests are also expected to be the same latency and size. When you select a load balancer to adopt, selecting the right algorithm is one of the areas that will make a big difference.
It is one of many answers that will vary depending on your requirements. To select an optimal load balancing solution, customers should be able to identify their long term requirements. This means not just how to distribute traffic equally, but also the required level of failover (a procedure whereby systems transfer control to a duplicate in the event of a failure), your encryption requirements, and more.
It’s also vitally important to have a sense of your anticipated loads — so that you don’t sell yourself short by failing to take growth into account or, on the other end of the spectrum, overspend on the necessary technology.
Know what you want
To add the best operational efficiency to your application delivery stream, make sure you seek out help from a company that’s able to answer all your questions about load balancing — and help you select an option that works best for your own requirements. Modern load balancing technologies also offer innovations like real-time monitoring of traffic to ensure proper load distribution.
They can additionally help spot and fix potential problems as they occur, prior to affecting any of the websites you’re operating. Load balancing is a crucial part of technical infrastructure for many. Make sure you make the right choices regarding it.