What are the different types of load balancers? Load balancers as a whole play a crucial role in shaping the flow of network traffic. Without them, you could very easily see a complete network get wiped out or slow to a crawl thanks to bandwidth over-saturation. As with any type of network appliance, there are multiple ways to use one.
This guide will go over the different types of load balancers, their pros and cons, and which you should choose for a particular task. Not all load balancers are made equally, and as such you’ll have to look at your particular use case before purchasing and installing one.
What Is a Load Balancer?
A load balancer is a network appliance that distributes traffic to two or more servers. These can be used in local instances, like a large business campus. You can also them for external traffic, like for users connecting to a streaming service.
Simply put, there are multiple uses for a load balancer. Having the ideal flow and shape of network traffic on your servers can be a difficult task. One of these network appliances can handle the work, however. They are fairly time-consuming to install, and they do require quite a bit of know-how to use effectively.
How Do They Work?
A load balancer takes a look at incoming traffic to a series of servers and evenly distributes it. Think of it like a series of traffic lights but with network data instead of cars. When properly configured a load balancer can keep the network as a responsive and fast environment, leading to great speeds while allowing for massive throughput.
They work by logically looking at the incoming data stream and evenly distributing it to two or more servers. You’ll typically see them in use with high-traffic websites, streaming services, and massive business campuses. Typically speaking, you’re going to see one in use when there is a ton of traffic going towards a singular network destination.
The Different Types of Load Balancers
Which type of load balancer is right for you? Keep reading to learn more about the different types and how to know which one you need.
Network Load Balancer
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One of the more common types of load balancers you’ll find is a network or Layer 4 type. This sort of load balancer is one you’ll find all over the place, especially on business campuses. As Layer 4 denotes, this operates at the Transport layer of the OSI model. As such, it handles routing traffic by looking at things like the IP address and ports.
Network load balancers aren’t going to look carefully at the application-sensitive data found in a particular transmission. Instead, you’ll find that is often the case with Layer 7 load balancer. These work great in high-paced environments, and you’ll typically see these more with internal routing for business complexes.
| Pros | Cons |
|---|---|
| They’re great for simply routing traffic via IP address. | Network load balancers don’t care about the content of a data stream. |
| Layer 4 means NAT is performed automatically. | Using solely a Layer 4 load balancer isn’t the best practice. |
HTTP Load Balancer
The HTTP load balancer serves as a good companion to a network variety. Out of the types of load balancers in common use, the HTTP load balancer is concerned with all the contents of data in transit across a network. These are also called Layer 7 load balancers, as they operate at the Application level of the OSI model.
These can be a great thing to implement on your outward-facing resources, as they analyze the content of a piece of data like the HTTP headers, SSL sessions, and authentications and evenly distribute those to two or more servers.
| Pros | Cons |
|---|---|
| Layer 7 load balancers analyze all incoming data before routing it to its intended destination. | They aren’t terribly concerned with ideal routing paths based solely on IP and MAC addresses. |
| These work great in customer-facing positions to maintain high availability. | Layer 7 load balancers are best used in a pairing. The setup for a pair of load balancers is quite complex. |
Cloud Load Balancer
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Out of all the types of load balancers, this is arguably the most complex in scope. There are many cloud providers out there with a wide range of services. One such service is just offering load balancing. Cloud or global server load balancers allow your business or web services to remain up and active even in the event of a location going offline.
This is great for maintaining business continuity, but it does take a degree of control out of your organization’s hands. Cloud load balancers act as multi-site Layer 4 and 7 implementations but spread across multiple locations.
| Pros | Cons |
|---|---|
| They allow load balancing to be conducted across multiple sites of operation. | These can be quite expensive services to engage as a whole. |
| Downtime can be nonexistent if one network segment is taken offline. | Your network team doesn’t have control over the day-to-day maintenance of a cloud load balancer. |
Hardware Load Balancer
Hardware is one of the most expensive types of load balancers you’ll find. These are purpose-built hardware network appliances that can serve in both the Layer 4 and 7 methods of operation. Hardware load balancers are less flexible than their counterparts and can be quite complex to install.
These aren’t typically required for modern load balancing. While there is no such thing as an easy load balancer to configure, hardware is costly. In the event of failure, you’re going to have to wait on a service technician to troubleshoot the equipment as well. They can work well in certain roles, especially if a company has someone on hand who is knowledgeable in their maintenance.
| Pros | Cons |
|---|---|
| They can handle massive volumes of traffic. | Hardware load balancers aren’t very flexible. |
| Dedicated hardware network appliances can be more robust than other solutions. | The pricing on these units is quite expensive as a whole. |
Software Load Balancer
Software load balancers are going to be the more common implementation you’ll see these days. Out of all the types of load balancers, software is arguably the most flexible. You can run these as Layer 4 and 7, giving a good amount of functionality in addition to its core function.
Software load balancers can be free and open-source, or a paid enterprise solution. No matter what you’re paying, these are generally more cost-effective as a whole when compared to hardware. They don’t handle nearly as much concurrent traffic as a piece of hardware, sadly.
| Pros | Cons |
|---|---|
| Software can be free or it can had quite affordably from commercial sources. | Software load balancers don’t handle nearly as much traffic as a hardware unit. |
| Installation and setup can be fairly flexible for software. | Open-source software is going to require you to be well-versed in its operation and maintenance. |
Virtual Load Balancer
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Of all the types of load balancers on this list, virtual solutions are perhaps the most unusual. These load balancers act as a combination of software and hardware. The basic concept is that you’re running a virtual load balancer in conjunction with virtual machines on a server. This is a fairly typical deployment for many servers since you’ve got plenty of cores to handle the processing.
Virtual load balancers are among the most challenging to properly implement and administer. They also have many of the same drawbacks seen with both software and hardware load balancers. As such, you’ll have to analyze whether using one of these is truly necessary for your use case.
| Pros | Cons |
|---|---|
| They combine the functionality of software load balancers with the more robust traffic routing seen in hardware. | Virtual load balancers are highly complex installations. |
| Virtual load balancers allow you to run multiple servers as VMs and route the traffic accordingly. | They have a lack of visual feedback, and automation capability, and cannot scale. |
Picking the Right Load Balancer: Step by Step
Network Type
The overall use case of your network is going to determine which to pick out of any of the types of load balancers. You don’t want to spend time messing around with a Layer 7 load balancer when you’re just routing traffic to central servers in a local business complex.
Local and wider area networks are going to have different overall needs when it comes to a load balancer. Before deciding to implement a load balancer, take a look at the needs of your network. Choosing something that doesn’t fit the needs of your network is going to be a waste of time and money when it comes down to it.
Ease of Installation
There is no such thing as an easy load balancer to install. However, the type you install is going to have a fairly large impact on the ease of installation. Hardware and virtual load balancers are vastly different beasts when compared to a pure software implementation.
Any networking department looking to use a load balancer will need to take the time to see if their network admins are up to the task. Going for a custom and complicated bespoke solution simply isn’t tenable if your network engineers lack the skill and knowledge to install one.
What to Know About Picking a Load Balancer
Load balancers are complex network appliances. Installing one is more out of necessity rather than need. If you’re running a smaller business campus with under 100 users, there likely isn’t going to be a huge need for a local implementation.
What load balancers provide is the ability to scale. You can handle far more traffic even with a Layer 4 and Layer 7 load balancer in software than you would hoping that traffic routes to the same location. Do be aware that load balancers themselves aren’t designed with security in mind, so you’ll need to consider your overall posture in addition to network needs.
Using the Different Types of Load Balancers: What It’s Like
When properly implemented, load balancers allow networks to be responsive and perform to the best of their ability. Think of using a site like Facebook or Netflix. It would be highly unusual for one of those sites to be sluggish and unresponsive under use, right? Both Meta and Netflix are likely using load balancers to distribute the millions of daily users they receive.
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