Load balancers became popular about two decades ago with the dawn of the Internet age. With the goals of optimizing the performance of newly created websites and ensuring that end users had a responsive experience when visiting a site, the load balancer was an essential front end to web servers and applications. The load balancer plays the traffic cop, using different algorithms to optimize the distribution of traffic to backend servers.
A load balancer can enhance the stability, efficiency, security, and availability of enterprise applications and services. Additionally, a load balancer can:
- Reduce server workload;
- Increase performance;
- Reduce Single Point of Failure through redundancy and rebalancing workloads when a server fails; and
- Improve scalability by the addition of new servers
For the longest time, the term “load balancer” meant one thing: a specialized hardware appliance with proprietary hardware to accelerate application traffic. However, advances in Intel architecture servers (in terms of processing power, memory, and network interfaces) have paved the way for software-only solutions to application delivery. These software-based approaches, when architected correctly, result in a superior platform for servicing modern applications.
What’s the difference between software- and hardware-based load balancers?
Hardware Load Balancers
Hardware load balancers are different from “software” load balancers in that the hardware load balancer requires a specialized piece of physical hardware with proprietary processors, ASICs, memory, and networking support. Throughout the late 90’s and early 2000’s, these were the only kind of load balancers available. Enterprises grew accustomed to the idea of purchasing load balancing appliances based on the projected growth in traffic. Hardware load balancers have to be physically installed and configured in the data center rack.
The main reason that load balancers were built with customized hardware was they were faster than using a purely software-based balancer. However, this gap has steadily become smaller with the advances in Intel architecture servers.
While purpose-built hardware may be faster than software running on any single x86 server, the elasticity, programmability, and horizontal scale delivered by software load balancers are quickly becoming the reason for webscale enterprises to choose them over hardware-based systems. Software load balancers can be scaled up vertically by using x86 servers with a higher number of processing cores or scaled out horizontally by adding many servers.
Another defining characteristic of a hardware load balancer is that it has a hard limit on the total number of SSL connections and data throughput that it can support. Once this limit is exceeded, the load balancer simply stops accepting new connections and performance degrades; creating a poor user experience for applications.
So, to add server capacity, more physical load balancing appliances will need to be installed as well—increasing costs.
Reasons to Use a Software Load Balancer
There are many reasons to use a software-based balancer over a hardware-based one, including:
- Cloud-Native Applications: Modern applications are built to work in any data center or cloud environment, and take advantage of infrastructure that can run on bare metal servers, virtual machines, or containers. Software load balancers mirror these capabilities and are the only viable solution for microservices and container-based applications. Large multinational enterprises are accelerating the adoption of software load balancers to bridge the needs of both traditional applications and cloud-native apps.
- Scalability: Software load balancers are able to scale up or down, since they use x86 server resources instead of separate dedicated hardware. This flexibility enables better capacity planning and on-demand scalability based on the real-time needs of applications.
- Per-app load balancing: A significant advantage of a software-defined load balancing strategy is that administrators can deploy custom application services on a per-application basis, instead of fitting multiple applications on a single monolithic hardware appliance to save hardware costs. This strategy naturally delivers benefits such as isolation, better availability, elimination of overprovisioning, and cost savings compared to hardware appliances.
- Hybrid cloud applications: Software load balancers provide a consistent application delivery architecture across different cloud environments. This eliminates the need to re-architect applications when migrating to the cloud or between clouds.
- Central management across clouds: Software load balancing platforms, architected with a separate data and control plane provide a single pane of glass to manage a distributed data plane of software load balancers. Administrators get centralized visibility and control to all virtual services configured and their corresponding pools and pool members. Application owners can enjoy self-service and install software load balancers on any server in any location or environment, without the time and effort of needing a support ticket to install dedicated hardware.
- Application Visibility and Insights: Software load balancers, architected with a separate data and control plane, can take advantage of their strategic location in the path of application traffic to analyze traffic patterns and generation application insights. These insights help administrators troubleshoot applications faster and help application teams with end user intelligence such as device type, location, and browsers used.
- Maintenance: Since there are no physical hardware appliances that need to be maintained or upgraded, on going operations are simplified and maintenance is less of an issue. If any individual software load balancer or x86 server fails, the control plane can make the decision to spin up another instance and put it into service.
- Redundancy/Resiliency: If a server running the load balancer is brought down, other load balancers can be quickly enabled to pick up the slack and prevent service disruptions.
- Ease of Deployment: Because there is no hardware to configure or install, deploying new load balancers can be done remotely in a matter of minutes. Most deployment and configuration operations can be automated with REST APIs and application rollouts can be sped up significantly instead of the normal process of waiting several days or weeks to provision new VIPs or load balancers.
Software load balancers enable new levels of automation, reliability, and scalability for enterprises of all sizes. They should be part of your shortlist for application delivery decisions as you get ready for a future consisting of a combination of traditional as well as cloud-native applications.
Learn more about Avi’s Ludicrous Scale elastic load balancer and its benefits today!