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. DNS load balancing is a software-defined approach to load balancing. Every time the DNS system responds to a new client request, it sends a different version of the list of IP addresses.
This ensures that the DNS requests are distributed evenly to different servers to handle the overall load. With non-responsive servers being automatically removed, DNS load balancing allows for automatic failover or backup to a working server. There are several methods or techniques that load balancers use to manage and distribute network load. They differ in the algorithms they use to determine which application server should receive each client request.
The five most common load balancing methods are:. In this method, an incoming request is forwarded to each server on a cyclical basis. When it reaches the last server, the cycle is repeated beginning with the first one. It is one of the simplest methods to implement but may not be the most efficient, as it assumes that all servers are of similar capacity.
There are two other variants of this method — weighted round robin and dynamic round robin — that can adjust for this assumption. It uses an algorithm to generate a unique hash key, or an encrypted version of the source and destination IP address. In the Least Connections method, traffic is diverted to the server that has the least amount of active connections.
Ideal for scenarios when there are periods of heavy traffic, this method helps distribute the traffic evenly among all available servers. In the least response time method, traffic is directed to the server that satisfies two conditions — it should have the fewest amount of active connections and lowest average response time.
In this method, the load balancer looks at the bandwidth consumption of servers in Mbps for the last fourteen seconds. The one that consumes the least bandwidth is chosen to send client requests to. At the end of the day, load balancing is about helping businesses effectively manage network traffic and application load in order to give end users a reliable, consistent experience.
In doing this, load balancers provide the following benefits. Load balancing helps businesses stay on top of traffic fluctuations or spikes and increase or decrease servers to meet the changing needs.
This helps businesses capitalize on sudden increases in customer demands to increase revenue. For example, e-commerce websites can expect a spike in network traffic during holiday seasons and during promotions. The ability to scale server capacity to balance their loads could be the difference between a sales boost from new or retained customers and a significant churn due to unhappy customers.
It is not uncommon for website servers to fail in times of unprecedented traffic spikes. But if you can maintain the website on more than one web server, you can limit the damage that downtime on any single server can cause. Load balancing helps you automatically transfer the network load to a working server if one fails. You can keep one server in an active mode to receive traffic while the other remains in a passive mode, ready to go online if the active one fails.
This arrangement gives businesses an assurance that one server will always be active to handle instances of hardware failure. The ability to divert traffic to a passive server temporarily also allows developers the flexibility to perform maintenance work on faulty servers. You can point all traffic to one server and set the load balancer in active mode.
Your IT support team can then perform software updates and patches on the passive server, test in a production environment and switch the server to active once everything works right. Load balancing helps businesses detect server outages and bypass them by distributing resources to unaffected servers.
This allows you to manage servers efficiently, especially if they are distributed across multiple data centres and cloud providers. This is especially true in the case of software load balancers which can employ predictive analytics to find potential traffic bottlenecks before they happen. Per app load balancing provides a high degree of application isolation, avoids over-provisioning of load balancers, and eliminates the constraints of supporting numerous applications on one load balancer.
Load balancing automation tools deploy, configure, and scale load balancers as needed to maintain performance and availability of applications, eliminating the need to code custom scripts per-app or per-environment. Per application load balancing offers a cost-efficient, elastic scale based on learned traffic thresholds and is particularly beneficial for applications that have matured beyond the limitations of a traditional, hardware load balancer.
Weighted load balancing is the process of permitting users to set a respective weight for each origin server in a pool. Depending on their respective weights and the load balancing weight priority, traffic will be rebalanced to the remaining accessible origins. An underestimated aspect to weighted load balancing are the nodes.
Nodes that restart begin again with an empty cache, and while the cache is repopulating it makes the node slower, which results in slowing down the entire collection. This is where heat weighted load balancing comes into focus by aiming to have low latency. The heat of each node is a factor in enhancing the node selection in the coordinator, so as a node is being rebooted, latency remains at a low level. Round robin load balancing has client requests allocated throughout a group of servers that are readily available, then is followed by all requests redirected to each server in turn.
In contrast to the weighted load balancing algorithm, the weighted round robin load balancing algorithm is used to schedule data flows and processes in networks. This process becomes cyclical when the algorithm commands the load balancer to return to the beginning of the list and repeat its procedure again.
Reliable and efficient, weighted round robin load balancing is a simple method and the most commonly used load balancing algorithm. Periodically, load balancers will perform a series of health checks to make sure registered instances are being monitored. Regardless of the instances being in a healthy or unhealthy state, all registered instances will receive load balancer health checks.
An instance health status shows as such:. The load balancer will only send requests to healthy instances, so it will not send requests to an instance with an unhealthy status. Once the instance has returned to a healthy state, the load balancer will continue to route requests to that instance. A stateful load balancer is able to keep track of all current sessions using a session table.
Before picking the right server to handle a request, it is able to look at a number of things using a distributed load balancing algorithm, such as the load of the different servers. Once a session is initiated and the load distribution algorithms have chosen its destination server, it sends all the upcoming packets to the server until the session comes to a close. Contrary to the process of stateful load balancing, stateless load balancing is a much simpler process.
The most common method of a stateless load balancer is by making a hash of the IP address of the client down to a small number. The number is used for the balancer to decide which server to take the request. It also has the ability to pick a server entirely by random, or even go round-robin. The hashing algorithm is the most basic form of stateless load balancing.
Since one client can create a log of requests that will be sent to one server, hashing on source IP will generally not provide a good distribution. However, a combination of IP and port can create a hash value as a client creates individual requests using a different source pot.
An application load balancer is one of the features of elastic load balancing and allows simpler configuration for developers to route incoming end-user traffic to applications based in the public cloud. As a result, it enhances user experiences, improves application responsiveness and availability, and provides protection from distributed denial-of-service DDoS attacks. A load balancing router, also known as a failover router, is designed to optimally route internet traffic across two or more broadband connections.
Broadband users that are simultaneously accessing internet applications or files will be more likely to have a better experience. This becomes especially important for businesses that have a lot of employees trying to access the same tools, applications, etc. Complete your digital transformation with our next-gen application delivery platform. Blog Contact Support. Request a Demo. An Introduction to Load Balancing.
About Load Balancers. History of Load Balancing. Load Balancing and Security Load Balancing plays an important security role as computing moves evermore to the cloud. Load Balancing Algorithms There is a variety of load balancing methods , which use different algorithms best suited for a particular situation. Least Connection Method — directs traffic to the server with the fewest active connections.
Most useful when there are a large number of persistent connections in the traffic unevenly distributed between the servers. Least Response Time Method — directs traffic to the server with the fewest active connections and the lowest average response time.
Round Robin Method — rotates servers by directing traffic to the first available server and then moves that server to the bottom of the queue. Most useful when servers are of equal specification and there are not many persistent connections. IP Hash — the IP address of the client determines which server receives the request. Load Balancing Benefits. Load balancers have different capabilities, which include: L4 — directs traffic based on data from network and transport layer protocols, such as IP address and TCP port.
L7 — adds content switching to load balancing. Load Balancing with App Insights. Using a Software Load Balancer for Application Monitoring, Security, and End User Intelligence Administrators can have actionable application insights at their fingertips Reduce troubleshooting time from days to mere minutes Avoid finger-pointing and empowers collaborative issue resolution.
Download Now. Software Load Balancers vs. Hardware Load Balancers. Software Pros Flexibility to adjust for changing needs. Ability to scale beyond initial capacity by adding more software instances. Lower cost than purchasing and maintaining physical machines.
Software can run on any standard device, which tends to be cheaper. Load balancers originated as hardware solutions. Hardware provides a simple appliance that delivers the functionality with a focus of performance. Hardware-based load balancers are designed for installation within datacenters.
They are turn-key solutions that do not require the dependencies that software-based solutions require such as hypervisors and COTS hardware. As network technologies evolved, software-defined, virtualization, and cloud technologies have become important. Software-based load balancing solutions offer flexibility and the ability to integrate into the virtualization orchestration solutions. Some environments such as cloud require software solutions. The software load balancer is more suited for these environments with their flexibility and integration.
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.
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