Virtualization Flexibility: What Is Load Balancing in VMware

Virtualization Flexibility: What Is Load Balancing in VMware

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Optimization is an important topic of discussion in virtualization. One of the more prominent issues of virtualization and virtual infrastructures is optimizing the performance of VMs. In VMware, load balancing is one way of optimizing performance across all applications on virtual machines.

VMware infrastructures have on-premises protocols that distribute traffic across different servers, essentially optimizing the network and ensuring nodes are operational. This guide will go into more detail about load balancing and explain the logic behind one of virtualization’s greatest flexibility.

With that said, let’s start.

What is Load Balancing?

Load balancing allows traffic to spread across multiple servers and hosts and ensures systems don’t get crowded. Load balancing works through load balancers, effectively making the virtual infrastructure more efficient. In virtualization, load balancers optimize response time and ensure all network nodes are fully utilized, essentially preventing nodes from going into idle mode.

In VMware, load balancing is available through VMware NSX. Instead of the traditional hardware load balancing option, virtual machines utilize software-based load balancing. In software load balancing, there is no physical device. Instead, the load balancers are part of a software.

The software can be deployed on a physical host or a virtual machine. For running virtual load balancers, VMware mimics software load balancers through virtualization.

How Does Load Balancing Work in VMware?

Virtual load balancing works the same as hardware load balancing. However, a load balancer works with a virtual switch, a virtual port group, and other virtual components to stabilize the network. Additionally, VMware allows the creation of load balancing policies, where the original policy is based on the originating virtual port.

That means you can route the network based on a physical NIC load through a vSphere Distributed Switch. But VMware takes load balancing to a new level. Traditionally, load balancers were difficult to manage and even harder to optimize. A standalone load balancer needs to communicate with other load balancers on the network.

Luckily, VMware solves this problem through a software where you can manage all your load balancers from a central location. That means you can manage virtual switches and physical network adapters, configure NIC teaming, and other load-balancing components. Additionally, you have more ways to edit teaming and failover orders.

How do Load Balancers determine Where to Send Network Traffic?

Load balancing in virtualization utilizes several methods to determine the correct path for network traffic. VMware utilizes four methods in total. Let’s explain them.

  • Round-Robin

Round-Robin is an algorithm and the simplest load balancing method. This method works by allocating traffic on available servers.

  • Least-Connections

The Least-Connections algorithm involves additional code to make the method more effective. Essentially, this method doesn’t pick the next available server, but rather the server that processes the least traffic orders. With Least-Connections, network traffic will always be distributed to the least busy server.

  • Least-Time

The Least-Time method is even more complex. Additionally, this method doesn’t compromise other aspects of servers such as speed and processing requests for network traffic availability. Instead, the Least-Time method will always pick the server with the fewest active requests and the fastest processing speed. The benefit of Least-Time is that it prefers the fastest servers and servers with the highest available network capacity.

  • Hash-Based

The final method is hash-based. This method assigns each user unique hash keys and destination IP addresses. The logic behind the algorithm is that returning users can be identified through the unique hash keys and IP addresses and reroute them to the same server they previously visited. The idea behind this method is to load faster.

Benefits of Software Load Balancing

We mentioned earlier that software load balancing works identically to hardware load balancing. The only difference is that there is no physical NIC load device to reroute traffic. Given that, we can add several benefits to software load balancing. Those are:

  • Scalability

Virtual systems and devices are easier to scale than physical ones. For example. physical network adapters are much more difficult to scale than virtual network adapters. The same logic applies to load balancers and other components, present in both physical and virtual networks. With software load balancers, you can add or discard virtual servers depending on your need.

  • Flexibility

Another difficult-to-look-past benefit is flexibility. Software or virtual load balancing makes your virtual network flexible. But how? The benefit ties to the idea that software load balancers work irrespective of your virtual environment. Where a physical load balancer might take issue with a physical switch or MAC address, a software-based load balancer doesn’t. It is fully programmable to work within any environment, cloud, standard virtual OS, and even bare metal.

  • Cost-Efficiency

The third benefit of software load balancing is cost efficiency. To easily explain the benefit, consider a modern virtual infrastructure with a standard physical one. Virtual infrastructure costs nowhere near a physical one to set up. This means there are no physical components, no hardware, and no space requirements for servers. Software load balancers aren’t physical devices, so there are no costs to purchase them. Most commonly, organizations turn to LBaaS (load-balancing as a service) for all of their load-balancing needs.

  • Security

Finally, there’s the benefit of security. Since software load balancers sit between the client and the server, it dictates network traffic based on IP hash. That means the load balancer can reject any suspicious requests by examining the IP and other components. This gives you an additional layer of security.


That concludes this guide on load balancing in VMware. We hope you found this guide useful and will consider the advantages of software load balancers the next time when setting up your virtual infrastructure.