“Load balancing is a methodology of efficient distribution networks or applications traffic across between multiple servers and websites of servers in a server farm. There is no single server that bears too much load demand.”
Each and Every load balancer presents between client devices and backend servers, receiving and after that distributed incoming requests to other available servers that are capable, available to fulfilling their requests. To spread the work equally, balancing load improves application responses. It is also increases the availability of applications and websites for clients.
For modern applications and websites can’t run without load balancing or load balancers. Before a time load balancing has been added to additional capabilities including security and applications.
It is also an essential part of cloud computing. Cloud systems are built to optimize the loads for one particular node of a network. When loads of the devices are balanced amongst different servers inside a single cloud server between multiple CPUs and Hard Disks.
It was introduced for various reasons. Some of the reasons behind the load balancing introduction thems are :
For the better speed and performance of every single node.
It will also keep saving the hitting their threshold by dropping down for their performance.
It is also used for distributing the traffic into multiple nodes or devices so that load of the single instance will be distributed chances of failure will be reduced.
It is also reduced the threat of failure of devices.
It will also help to reduce the slowdown of the servers.
The load balancer will reduce the dropdown of the requests to the servers.
It also prevents the resources from crashes.
Different Algorithms used by load balancing are:
Least response time
Opportunistic load balancing
Minimum to maximum load-balancing algorithm and vice -versa.
Least bandwidth method.
Load balancing will be performed by different techniques:
By the use of physical servers. It is called hardware load balancers
By the virtualized servers are also called software load balancers
As a Cloud Load Balancer as a Service (LBaaS), known as AWS Elastic Load Balancer.
Some of the load balancers are performed by dedicated load balancers which are also called Application Delivery Controller with the capabilities of balancing the loads. It will reside on-premises on regional and global data centers in the cloud, It will be easy to set up the load balancing of services anywhere in the world.
Load Balancer Works
Load balancing will be work on the layer 4 and 7 of the Open Systems interconnection (OSI) Model. It will route the traffics of Layer 4 and 7. They should advertise the IP addresses as the destination IP’s for a website or services. It receives the incoming traffic requests on the selected servers to process each and every request:
Layer 4 load balancers are Transport Layer that does not inspect the content of every data packets.
It will make routing on a decision based on indifferent ports and Ip addresses of the incoming request from the clients and users of NAT Network Address Translation for routing the requests and responses to the selected servers to the requested client.
Layer 7 balancers will route the traffics at the application levels. It inspects the incoming content of the package by package basis of the Layer 7 load balancers. Load balancers client requests inside the selected servers in the network using different factors compare to Layer 4 load balancer. For Example HTTP headers and SSL sessions ID’s. Layer 7 Load balancers have more computational power on comparing to Layer 4 load balancers. Also will be more efficient route-based and context-based factors.
GSLB (Global Server Load Balancing): It extends the core of Layer 4 and 7 capabilities so they are applicable to multiple geographically distributed server farms.
GSLB (Global Server Of Load Balancing) can be route traffic between the multiple geographically servers located on the premises data centers, in the public and private clouds. It is generally configured to send clients requests to the nearest geographic location of the serves to servers that have the least response time.
Hardware Load Balancer vs Software Load Balancer
Hardware Load balancer runs proprietary software loaded into a machine that often uses a specialized processor for optimization of the resources requests over it.
It is difficult to scale up as we need to add more hardware resources as the load increases.
It is very expensive because of the high cost of purchase and maintenance of a physical load balancer.
It will also need a specialized consultant persons for maintenance and installation.
We also have to increased security of physical resources.
Software Load Balancer usually runs on the less expensive commodity hardwares. It will be installed and run anywhere in the public or private clouds such as AWS and Azure.
It is less expensive as runs on commodity hardware.
It is easy to scale up and down by simply running additional instances of the load balancer.
Flexibility to adjust based on changing needs of the clients.
It is also run anywhere anytime
Some smart software-based load balancers provides the predictive analytics that determines traffic bottlenecks.
Redundant load balancers:
A load balancers has become a single point of failures. To avoid a single point of failures we can add more than one resource of load balancer on different physical machines in the same cluster of machines over a cloud or a physical loaction. In case of main load balancer goes down then second load balancer takes charge over it.