Why load balance

Some industry standard algorithms are:. Layer 7 load balancers can further distribute requests based on application specific data such as HTTP headers, cookies, or data within the application message itself, such as the value of a specific parameter. Load balancers ensure reliability and availability by monitoring the "health" of applications and only sending requests to servers and applications that can respond in a timely manner. To learn more on load balancing, visit DevCentral.

It could also be incorporated into application delivery controllers ADCs — network devices designed to improve the performance and security of applications in general. OSI is a set of standards for communication functions for a system that does not depend on the underlying internal structure or technology. According to this model, load balancing should occur at two layers for an optimum and consistent user experience.

These load balancers make the decisions on how to route traffic packets based on the TCP or UDP ports that they use and the IP addresses of their source and destination. L4 load balancers do not inspect the actual contents of the packet but map the IP address to the right servers in a process called Network Address Translation. L7 load balancers act at the application layer and are capable of inspecting HTTP headers, SSL session IDs and other data to decide which servers to route the incoming requests to and how.

Since they require additional context in understanding and processing client requests to servers, L7 load balancers are computationally more CPU-intensive than L4 load balancers, but more efficient as a result.

There is another type of load balancing called Global Server Load Balancing. This extends the capabilities of L4 and L7 load balancers across multiple data centers in order to distribute large volumes of traffic without negatively affecting the service for end users.

These are also especially useful for handling application requests from cloud data centres distributed across geographies. Load balancing came to prominence in the s as hardware appliances distributing traffic across a network. As internet technologies and connectivity improved rapidly, web applications became more complex and their demands exceeded the capabilities of individual servers.

There was a need to find better ways to take multiple requests for similar resources and distribute them effectively across servers. This was the genesis of load balancers. Since load balancing allowed web applications to avoid relying on individual servers, it also helped in scaling these applications easily beyond what a single server could support. The rise of ADCs in the early s was a major milestone in the history of application load balancing.

ADCs are network devices that were developed with the goal of improving the performance of applications and application load balancing became one of the ways to achieve that. But they would soon evolve to cover more application services including compression, caching, authentication, web application firewalls and other security services.

As cloud computing slowly began to dominate application delivery, ADCs evolved along as well. Having started out as hardware appliances, ADCs also took the form of virtual machines with the software extracted from legacy hardware and even pure software load balancers. Software ADCs perform tasks similar to their hardware counterparts but also provide more functionalities and flexibility.

They allow organizations to rapidly scale up application services in the cloud environments to meet demand spikes, while maintaining security. Load balancers could take the form of hardware devices in the network, or they could be purely software-defined processes. No matter which form they come in, they all work by disbursing network traffic to different web servers based on various conditions to prevent overloading any one server.

Think of load balancers like traffic cops redirecting heavy traffic to less crowded lanes to avoid congestion. Load balancers effectively manage the seamless flow of information between application servers and an endpoint device like a PC, laptop or tablet. The servers in question could be on-premise, in a data centre or in the cloud.

Without a load balancer, individual servers can get overwhelmed and applications can become unresponsive, leading to delays in response, poor use experiences and loss of revenues. The exact mechanism by which load balancers work depends on whether they are hardware appliances or software.

Hardware-based load balancers work by using on-premises hardware and physical devices to distribute network load. These are capable of handling a large volume of network traffic and high-performance applications. Hardware load balancers may also contain built-in virtualization, consolidating many instances in the same device.

Since they use specialized processors to run the software, they offer fast throughput, while the need for physical access to network or application servers increases the security.

On the downside, hardware load balancers can be costly as it requires purchase of physical machines and paid consultants to configure, program and maintain the hardware.

Software-based load balancers on the other hand can deliver the same benefits as hardware load balancers while replacing the expensive hardware. They can run on any standard device and thereby save space and hardware costs. Software load balancers offer more flexibility to adjust for changing requirements and can help you scale capacity by adding more software instances. They can also easily be used for load balancing on the cloud in a managed, off-site solution or in a hybrid model with in-house hosting as well.

Elastic Load Balancer ELB solutions are far more sophisticated and offer cloud-computing operators scalable capacity based on traffic requirements at any one time. Elastic Load Balancing scales traffic to an application as demand changes over time.

It also scales load balancing instances automatically and on-demand. As elastic load balancing uses request routing algorithms to distribute incoming application traffic across multiple instances or scale them as necessary, it increases the fault tolerance of your applications.

Load balancing algorithms are formulas to determine which server to send each client connection to. The algorithms can be very simple, like round robin, or they can be advanced like agent based adaptive.

No matter the case, the purpose of the algorithm is to send the client connection to the best suited application server. The most commonly recommended algorithm is least connection. This algorithm is designed to send the connection to the best performing server based on the number of connections it is currently managing. Least connections takes into account the length of each connection by only looking at what is currently active on the server.

The Kemp LoadMaster load balancer is designed to optimize the load balancing experience. LoadMaster is a software-based solution that is also available as a hardware appliance. Kemp focuses on the core load balancing technologies to ensure a simplified configuration and management process. This focus translates to a significant TCO savings for the life of the technology. Kemp offers world class support through an extensive organization of experts to offer assistance to customers 24x7.

Kemp has built a team of load balancing and networking experts over many years to become a premier technology organization with over , deployments in countries. Kemp LoadMaster is the leading load balancer available on the market today. Affordable load balancers available as both virtual load balancers and hardware load balancers.

Skip to main content. What is a Load Balancer A load balancer can be deployed as software or hardware to a device that distributes connections from clients between a set of servers.

Expert Series What is Load Balancing? Please check your inbox for your exclusive Webinar link. Have a specific question about load balancing? Jump through the article through the links below; What is load balancing? What a load balancer supports? How does a load balancer work?