High Availability Load Balancing: What Is It? | Parallels Insights!

What Is High Availability Load Balancing? 

high availability load balancingHigh availability load balancing (HALB) is crucial in preventing potentially catastrophic component failures. Central to this concept is the use of a system of primary and secondary load balancers to automatically distribute workloads across your data centers. This redundancy in both your load balancers and servers ensures near-continuous application delivery. In such a system, when either a load balancer or server fails, corresponding backup equipment takes its place.

High availability load balancing and load balancers. 

To ensure high availability, you should eliminate single points of failure and deploy additional servers to serve as backups in the event of worst-case scenarios. This is because, even when a load balancer is in use, a server may still go down if it fails to handle the volume of incoming traffic. When this happens, your failover mechanisms should spring into action and shift the load of the failing piece of equipment to your other servers. Thus, the integrity of your IT infrastructure is maintained.

You should ensure that your load balancing setup is also highly available, since your best-laid plans will amount to nothing if your load balancers fail.

Thus, you should at least have another load balancer to serve as a backup in case your primary load balancer goes down. This so-called N+1 model is the least costly high availability load balancing model.

Active-Active and Active-Passive are the other high availability load balancing models. In Active-Active, two or more load balancers operate at the same time. In Active-Standby, each load balancer has an assigned backup that will take over its load in case it goes down.

The high availability load balancing approach you take will ultimately depend on your requirements.

Key Benefits of High Availability Load Balancing

Load balancers serve to distribute network traffic and application workloads across several servers so that not one is overwhelmed. The high availability, or continuous operation, of your IT infrastructure is achieved through this redundant system.

Ideally, this switch over from a failing piece of equipment to the other one should occur seamlessly so that users do not encounter any downtime. In the real world, minimal downtime is the more achievable objective.

Highly available load balancers serve to protect your organization from Distributed Denial of Service (DDOS) attacks through SYN cookies and delayed binding. They also conduct regular health checks to ensure that your applications and servers can still handle the volume of transaction requests. When they detect impending failure, they reroute traffic to application copies and backup servers.

In the case of web servers, highly available load balancers can separate TLS requests from the main HTTPS requests and speed up web server responses in the process.

Hardware load balancers 

Hardware load balancers consist of physical hardware, such as an appliance. These direct traffic to servers based on criteria like the number of existing connections to a server, processor utilization, and server performance. These come with their firmware that requires maintenance and software updates 

Hardware load balancers offer better performance and control with a fuller range of featureslike Kerberos authentication and Secure Sockets Layer (SSL) hardware acceleration—but require some level of proficiency for management and maintenance. Due to being hardware-based, these load balancers are not very flexible and scalable, so there is a tendency to over-provision hardware load balancers. 

Software load balancers 

Software load balancers are more straightforward to deploy than hardware versions. They are also more cost-effective and flexible and used in conjunction with software development environments. The software approach provides you the flexibility of configuring the load balancer to your environment’s specific needs. Compared to hardware versions, which offer more of a closed-box approach, software balancers grant you more liberty when it comes to changes and upgrades. 

Software load balancers can come as prepackaged virtual machines (VMs) to spare you some of the configurations but may not offer all of the features available with hardware versions. 

Software load balancers are available as standalone solutions that require configuration and management or as a cloud service—known as Load Balancer as a Service (LBaaS). Choosing the cloud service frees you from the maintenance, management, and upgrading of the locally installed server. The cloud provider handles these tasks. 

How Parallels RAS helps with high availability load balancing 

Parallels® Remote Application Server (RAS) offers you a two-point load balancing to ensure high availability. The first point of contact is an external high availability load balancer (HALB) appliance, which is a standalone VM deployed in UNIX. This is responsible for load balancing the traffic between the gateways before the actual connection. 

The second point of contact is configurable from inside the Parallels RAS Console and is about the traffic after connecting through the gateways. There are two methods: round-robin and resource-based load balancing mechanisms. 

Both HALB points are included in the standard license and require minimum effort to set up. The integrated load balancing is automatically enabled by default. 

Download the Parallels RAS trial and experience the benefits of high availability load balancing. 


IBM | https://www.ibm.com/cloud/learn/load-balancing 

NGINX | https://www.nginx.com/resources/glossary/load-balancing/ 

Digital Ocen | https://www.digitalocean.com/community/tutorials/what-is-high-availability 

Wikipedia | https://en.wikipedia.org/wiki/Load_balancing_(computing) 

HAProxy | https://www.haproxy.com/de/loesungen/high-availability/ 

Parallels | https://www.parallels.com/products/ras/capabilities/load-balancing/