What is load balancing?
Load balancing is the process of evenly dispersing network traffic across multiple servers to avoid overworking them. Server professionals like IT managers and network administrators use load balancing across company servers to ensure a smooth workflow and keep an eye on which servers are used and how often.
Load balancing in networking isn't just about company servers. Load balancing tools help popular websites distribute incoming traffic to ensure proper functionality.
Neglecting to do this causes website downtime, and the more a website is unavailable, the more visitors are turned away. If the website aims to make sales, customers are lost just because the network isn't balanced appropriately to support traffic.
Companies use load balancing software to automate how resources and traffic are portioned out amongst websites, applications, and servers. These solutions allow businesses to monitor network traffic, disperse resources as needed, adjust workloads to offset traffic, and utilize backup services in case of server failure or downtime.
Types of load balancing
There are seven types of load balancers. All are useful in dispersing traffic effectively, and companies may combine different types according to their needs.
- A network load balancer (NLB) is the most common and well-known load balancer that simply focuses on distributing network traffic evenly between a group of servers.
- An application load balancer (ALB) distributes network traffic based on existing variables. It uses automation to make load balancing decisions with content element awareness.
- A global server load balancer (GSLB) helps in distributing traffic amongst global servers. This improves performance by relying on servers that are geographically closer.
- A hardware load balancer device (HLD) is a physical, on-premise device that distributes network traffic.
- A software load balancer (SLB) makes use of a virtual software installation for balancing network traffic. These can be commercially sold or applied through an open-source system.
- A virtual load balancer (VLB): combines the previous two load balancers by running hardware applications on a virtual machine.
- A gateway load balancer (GLB) focuses on security elements by managing firewalls and intrusion prevention systems. It balances the load by creating one point of entry and exit to distribute traffic.
Load balancing algorithms
There are two significant types of load balancing algorithms: static and dynamic. There is no right or wrong algorithm or method for load balancing servers. There is simply the best way to approach it depending on the necessities and capabilities of a company and its server system.
Static load balancing algorithm
In static load balancing, traffic is distributed throughout different servers without keeping the state of those servers in mind during the process. How the traffic is distributed is determined by what is known about the server system altogether.
It is a more straightforward algorithm to implement and maintain, although it may not be considered as detailed in its balancing methods.
There are six different types of static load balancing algorithms:
- Round-robin rotates how traffic is distributed to servers.
- Weighted round-robin rotates traffic distribution with specific characteristics in mind.
- Source IP hash converts traffic sources and IP addresses into a hash assigned to a particular server.
- Randomized static randomly distributes traffic amongst servers.
- Central manager disperses traffic using a central node that chooses the processer with the least current traffic.
- Threshold assigns incoming traffic to the newest servers available.
Dynamic load balancing algorithm
With dynamic load balancing, the current state of the servers is considered as traffic is distributed. This method helps traffic move more efficiently by supplying a more robust course of action with more information to back up the way it balances.
Unlike the static algorithm, dynamic is not as straightforward to implement and can take a lot of time and effort to design and install.
There are four different types of dynamic load balancing algorithms:
- Least connection identifies which servers currently have the least connections and distributes traffic to those as needed.
- Weighted least connection allows users to assign weights to different servers. This pinpoints how many connections a server can handle and, therefore, how they are balanced.
- Weighted response time determines the speed of a server’s response time. Users may choose to weigh these servers at a rate where they can handle more connections because they respond faster than others.
- Resource-based (adaptive) relies on the resources available within a server at a specific time. Usually, a computer program is installed on the system to track this information. The network load is balanced depending on which server is the most prepared to handle incoming traffic.
Benefits of load balancing
There are many advantages to implementing a load balancing technique into an existing server system. Once companies choose the correct algorithm or method for their environment, they can reap the benefits.
- Improved performance. The more balanced networking traffic, the less chance of creating bottlenecks from overworked existing servers. When load balancing is done right, optimal performance is a given.
- Guaranteed reliability. Load balancing’s primary goal is to ensure that server downtime is minimal and measure the recovery time objective (RTO). When there is a backup plan to the backup plan, issues are much less likely to occur.
- Enhanced user experience. When companies invest in the reliability of their servers, users are left with a more seamless and pleasant experience.
- Increased flexibility. It can be common for companies to want to change elements of their networking system without disrupting services. Creating a solid load balancing system can allow specific servers to be shut down for maintenance while the others pick up the slack and keep operations running smoothly.
- Added security layers. Companies should think of their servers as their shields. The more there are, the more challenging to breach. Load balancing essentially creates an army of strong, capable servers to stall attacks in time for security measures to be put into place to stop them.
- Predictable downtimes. Certain load balancing methods can actually help companies predict instances of downtime or error in advance. Companies can use this information to address those issues and balance traffic as necessary before the problem becomes an emergency.
Load balancing best practices
There are a few tips and tricks that companies should keep in mind as they decide to implement load balancing and as they maintain and manage the process.
- Determine long-term needs. The benefits of load balancing may take a while to come to fruition. In order to choose the correct method of balancing for a specific business, it’s important to identify long-term network needs. This will also help to avoid having to change things later on.
- Predict potential load. It’s not always easy, but businesses should try to predict how much network traffic they expect to incur. This educated guess helps them choose an algorithm that can balance their traffic effectively.
- Create a budget. Whether a company chooses a load balancing method based on software or hardware, they need to make some purchase decisions. Budget tracking for the project should be organized ahead of time to prepare for those costs.
- Keep maintenance in mind. Load balancing isn’t over once the processes have been implemented. Every type of load balancing requires consistent upkeep and management. Companies should keep this in mind as they budget and allocate workload so the load balancing materials are maintained.
Hardware load balancing vs. software load balancing
As mentioned earlier, hardware load balancing and software load balancing are both solid choices for building a load balancing system. However, they differ in what they can offer to a company.
Hardware load balancing uses a physical load balancer that is held on-site. It acts as the middleman between incoming traffic and company servers.
Usually, companies will implement customized rules onto the hardware to optimize traffic distribution. Because hardware load balancers are physical in nature, they require a lot of attention for implementation and maintenance. Some companies may take issue with hardware load balancing devices as they attempt to scale and grow their server base.
Software load balancing uses a digital load balancer that lives in a virtual environment. These pieces of software can be installed directly onto existing servers or outsourced.
Like any other load balancer, it aims to distribute network traffic. Because software load balancers work digitally, they can expand to improve scalability as needed. Some companies may take issue with how expensive it can be to build and manage the software.
Alexandra Vazquez
Alexandra Vazquez is a former Senior Content Marketing Specialist at G2. She received her Business Administration degree from Florida International University and is a published playwright. Alexandra's expertise lies in copywriting for the G2 Tea newsletter, interviewing experts in the Industry Insights blog and video series, and leading our internal thought leadership blog series, G2 Voices. In her spare time, she enjoys collecting board games, playing karaoke, and watching trashy reality TV.
