Netscaler Basics – Load Balancing

In a Netscaler load balancing setup, the load balancing server is logically (virtual server) located between the client and the server farm, and manages traffic flow to the servers in the server farm. On the NetScaler appliance, the application servers are represented by virtual entities called Services.

The components of NetScaler load balancing setup:

1. Load balancing virtual server
The IP address, port, and protocol combination to which a client sends connection requests for a particular load-balanced website or application. If the application is accessible from the Internet, the virtual server IP (VIP) address is a public IP address. If the application is accessible only from the local area network (LAN) or wide area network (WAN), the VIP is usually a private (ICANN non-routable) IP address.

2. Service
The IP address, port, and protocol combination used to route requests to a specific load-balanced application server. A service can be a logical representation of the application server itself, or of an application running on a server that hosts multiple applications. After creating a service, you bind it to a load balancing virtual server.

3. Server object
A virtual entity that enables you to assign a name to a physical server instead of identifying the server by its IP address. If you create a server object, you can specify its name instead of the server’s IP address when you create a service. Otherwise, you must specify the server’s IP address when you create a service, and the IP address becomes the name of the server.

4. Monitor
An entity on the NetScaler appliance that tracks a service and ensures that it is operating correctly. The monitor periodically probes (or performs a health check on) each service to which you assign it. If the service does not respond within the time specified by the time-out, and a specified number of health checks fail, that service is marked DOWN. The NetScaler appliance then skips that service when performing load balancing, until the issues that caused the service to quit responding are fixed.

1. Create Server Objects

Configuration > Traffic Management  > Load Balancing > Servers > Add.

Provide web servers name and IP address, create 2 or more servers

2. Create Service Group

Configuration > Traffic Management  > Load Balancing > Service Groups > Add.

Provide Name the group and set the protocol to HTTP.

Click ‘No Service Group members’ and select server based. Select Port as 80 or 443.

3. Create “Monitors” to monitor the Service.

Click ‘No service Group to Monitor Binding’. Select pre-configured HTTP monitor and Bind.

4. Create Vitrual Server. Configuration > Traffic Management  > Load Balancing > Virtual Servers > Add.

Give the Virtual Server name, Protocol- HTTP, IP address and Port -80. This will be the VIP the NetScaler presents to the outside world.

Click ‘No load balancing Virtual Servers Service Group Binding’ and select the Service Group and Bind.

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About Murugan B Iyyappan

Working as a Technical Specialist - Citrix solutions architect with 13 years of experience in the IT industry. Expertise in Citrix XenApp and VMware in Windows platform.
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