How To Configure Application Load Balancing Through Netscaler

Load balancing is most useful part in netscaler, You believe or not in some organizations Netscaler is being used only as load balancer so hope this would great article for all.

Load balancing configuration is divided in to four parts first is Virtual Server object which is getting created on Netscaler and used as first point of contact for incoming traffic. Second is services object which is getting used for defining the nature of service like which type of service want to load balance example web services,tcp,ica etc. Third is Server object which is used as representation of hosted application server names where we can give IP or DNS name of back-end servers at which application resides. Fourth object is Monitor which is getting used for smart monitoring and make this Netscaler device as layer four device. Monitor basically do the pro active monitoring of all the load balancing members and help LB virtual server object to route traffic only towards live server objects incase any member server object became unresponsive then automatically traffic stop routing toward non responding object. which is very helpful for all the live infrastructure because there would be no end user downtime and at the same time it save lot of system admin efforts as well.

Let's start with the configuration part of load balancing,

(Don't forget to enable Load Balancing feature even if you have licence)

I am going to demonstrate this for new users so not using shortcuts and following bit lengthy way.At first navigate to Configuration then go to traffic management then go to load balancing and select server option,

On the right pane select the Add option. There would be new page open for filling details. Here give the name of server, Here one thing to be noted that this name is not real DNS name of server this would be used for admins understanding make it friendly. In next option give the IP of server or server DNS name and click on create button.

Following same create server objects for each application servers.

Now go to Services tab and from right pane select Add option. After that there would be new window comes asking for information Service Name this also for admins purpose so give friendly name and jump to other option here you select existing server option because we manually created server object just above. If we not created there we can select new server option for server object creation. Select protocol for which load balancing is required and mention port and select create. Please make sure we create one service object for each member server object,

After creation of each service one monitor also automatically created and bounded with the service object. To see that navigate to bottom of service object and there you can see that monitor object.

By default this monitor comes with tcp monitor only which verify only server ping status that it's responding or not. But to make it more efficient we can add other counter in this monitor which does protocol wise monitoring as well for ex. HTTP, ICA etc. To configure that click on forward button shown above and on popup window select Add Binding button. New popup window will appear where you can click on drop-down section if want to modify default TCP monitor and click on + symbol if want to add new monitor. Click on "Click to select" space and then list of all the available protocol will appear. Select which one you want and click on bind. That it your service object is fully configured. Repeat the same process for rest of the service object creation.

Now we been left only with last peace of cake which is Virtual server object creation so to do that go to Virtual Servers tab and on right pane select add button after that new window will open asking for Name/Protocol/IP Address type/IP Address port. Here we give the public IP we if are going to use it for public facing request or we give intranet IP if we user netscaler for intranet. Make sure to add destination SNIP if use for external IP's.(Check my other article describing about subnet IP and MIP. https://rajatcitrix.blogspot.in/2016/08/how-load-balancing-and-routing-works-in.html).

After clicking on ok our Virtual server object would be created but if you see  in service section it must be giving and error that "No load balancing virtual server service binding". This comes because we not yet bounded the service object. To bind that click on the error and new popup window will appear for selecting the service objects select all the service object and click on bind. By default our load balancing methodology is selected as least connection which means request will route to server which have least connection threads. If you want to change that then select Virtual server object and click edit after that from right panel select method and there you have options for selecting load balancing mechanism. 

That's it our first Load balancing configuration section is done.