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F5 load Balancer Training Introduction:

Load balancer training is a crucial element to any type of a network that is required to maintain high availability while gracefully handling sudden spikes in the traffic. In the event of a sudden increasing in traffic, the load balancers prevent the web application & database servers from becoming overloaded by distributing the traffic evenly across the servers. If a web server fails, then the load balancers will divert to any traffic away from that server, maintaining the availability of your website& the applications.

Global Online Trainings carries out all the sessions in an interactive and informative way. Following section gives the course content for F5 load balancer Online Training. We are specialized in delivering best trainings from expert consultants. Register for more Information.

Load balancer overview:

  • A load balancer is a device that acts as a reverse proxy & distributes network or application traffic across a number of servers. Load balancers are used to increase the capacity & reliability of applications.
  • They improve the overall performance of applications by reducing the burden on servers associated with maintaining & managing application & network sessions and also by performing application specific tasks.
  • Load balancers are generally grouped into two categories: Layer 4 & Layer 7. Layer 4 load balancers act upon a data that found in network & transport layer protocols such as, IP, TCP, FTP, UDP. Layer 7 load balancers distribute the requests based upon a data that found in application layer protocols such as HTTP.
  • Layer 7 load balancers can further distribute the requests based upon application specific data such as HTTP headers, cookies / data within the application message itself, such as the value of a specific parameter.
  •  load balancer improves the distribution of workloads across multiple computing resources, such as computers, a computer cluster, central processing units, network links or disk drives. 
  • Load balancer aims to optimize resource use, maximize throughput, minimize response time & to avoid overload of any single resource. Load balancer usually involves dedicated software or hardware, such as a multilayer switch or a Domain Name System server process.
  • Load balancer differs from channel bonding in that load balancing divides traffic between network interfaces on a network socket basis, while channel bonding implies a division of traffic between physical interfaces at a lower level, either per packet (Layer 3) or on a data link (Layer 2) basis with a protocol like shortest path bridging.
  • GoGrid provides hardware load balancing services using state-of-the-art F5 load balancing hardware that is set up & configured by our certified data center technicians. Using a unique “predictive” algorithm, traffic will be routed to the most efficient server. Using intelligent keepalives, all the servers in the pool can be monitored so that in the event that a server or the application on the server fails, requests are automatically & seamlessly forwarded to other servers.
  • Requests are received by both types of load balancers & they are distributed to a particular server based on a configured algorithm. Some industry standard algorithms are:
  • Round robin
  • Weighted round robin
  • Least connections
  • Least response time

Round Robin:

Round Robin load balancer takes all incoming connections & routes them one at a time, server by server in an equally distributed fashion with each server taking turns. If you have two servers, then incoming connections will alternate between the two. If you have 4 servers, connections will be routed to server 1, server 2, server 3 &  then server 4 before beginning the cycle again.

Least Connect:

Least Connect load balancer will route the incoming connections to the server with the lowest load on it. Connections that are sent to each server depending on the total number of concurrent sessions on the servers. If you have two servers, then the first with 24 sessions running & the second with 12 sessions running, then incoming connections will be routed to the server 2 until the ratio of connections changes.


Benefits of F5 Load Balancer:

The main benefits of load balancing are:

  • Better Scalability
  • High Availability
  • Better performance

Better scalabilty:

  • If you are experienced in increasing traffic & load on your application servers, there will be point where the server hardware, like CPU & memory, will become too expensive. In other words a single server will not scale well in performance or cost ratio in an increasing high load or traffic environment.
  • Limits in the web servers resources like number of threads or connections can often play a part too & maybe your web servers or application servers only scale up to a certain number of CPU cores or there is a limit to the amount of memory that they can use.
  • Using a load balancer to distribute traffic & load between your application &  database servers will give you a healthy & economical scalability. Basically you will double your traffic capacity when doubling the number of application servers behind a load balancer.
  • Add cache layers & other optimizations into the mix and you will get many times more load capacity in your stack.

Higher availability:

  • Let’s say that you have a fairly normal 99.0% uptime on your setup without load balancing. If you add load balancing & add 1 redundant server to your setup, you now get 99.9975% uptime This is because you now have a parallel system where the uptime is increasing exponentially with each  of new server added. Adding a 3rd server will reduce the monthly downtime to 3 seconds.
  • Add to that the convenience of automatic fail-over when doing maintenance work. You’ll love how you can just take anyone of your applications servers down for maintenance & let the load balancer direct the traffic to your other application servers.
  • How fast the F5 BIG-IP LTM load balancer will direct traffic away from an offline server & when it will start to use new servers on the inside, can be configured in many ways.

Better performance:

  • Modern high performance load balancers like the F5 BIG-IP LTM do a lot more than just distribute load & serve as fail-over between the  application servers.
  • If you have a heavely loaded application server, adding more application servers & a load balancer to distribute traffic between them will of course improve your application performance a lot.
  • But even under light load, a modern load balancer like the F5 BIG-IP LTM will often improve the performance & it has nothing to do with the number of application servers on the inside. The reason is that the F5 BIG-IP LTM make use of some lever optimization techniques like TCP optimizations.
  • So even under light load you will experience better performance, meaning lower response times & faster page load speed.

principles of Load Balancer:

  • The basic principle of a load balancer is to distribute load across a number of servers & to make those servers look like one big server to the outside world. The purpose of doing this is high scalability, availability & performance.
  • Before load balancers many companies are used DNS round robin to distribute load between 2 or more servers. They did this because many saw no way to have a single server handle the increasing amount of the traffic.
  • The DNS round robin method uses multiple A-records, one for each participating server, for the same domain name in DNS. Traffic for the domain will then be randomly distributed to the servers.
  • The solution worked for scaling, which was the purpose. But in terms of high availability, this method does not work. The problem is that DNS cannot know which server is available or not.
  • Even if never sleeping administrators would change A-records each time a server goes offline, low TTL (Time-To-Live) values or other methods, the DNS is simply not suitable for high availability. So the load balancer was born from the need to do both scaling of load & for high availability.

 Requirements for using Load Balancer:

  • The requirements for enjoying the benefits of a load balancer would be that your load balanced servers &  the application that running on them are able to serve the same content.
  • Depending on the nature of your application, they need to syncronize & either continuously or on a sufficient short schedule.
  • If you are running a blog, it might be ok that you miss an update or a comment while one of your servers is down. If you run a financial application you might need to be absolutely sure that your application & database servers are syncronized at all times.
  • Your options also depends on the platform & systems you use for your application. Some are easy to operate in a load balanced environment, some are harder & need additional tools & software.

Key Features of Load Balancer:

  • GoGrid is the only cloud provider of hardware load balancer
  • Existing GoGrid accounts are equipped with F5 load balancers — at no extra cost
  • Our load balancers can be easily provisioned using the API or customer portal
  • Maximum number of servers load balanced by a single virtual IP address: 1000
  • Maximum number of connections handled by a single real IP address : 1000

Uses of f5  Load balancer:

A load balancer is a device that acts as a reverse proxy & distributes network or application traffic across a number of servers.

 Load balancers are used to

  • increase capacity
  • reliability of applications.