The NetScaler Application Delivery Controller (ADC) is a Citrix © Systems core networking product. ADC improves the delivery speed and quality of applications for an end user. The product helps business customers perform tasks such as traffic optimization, L4-L7 load balancing, and web app acceleration while maintaining data security.
NetScaler ADC monitors server health and allocates network and application traffic to additional servers for efficient use of resources. It also performs several kinds of caching and compression. It can be used as a proxy server to process Secure Socket Layer (SSL) requests instead of servers (SSL offloading).
This blog covers the basic Hyper Text Transfer Protocol (HTTP) site load balancing configuration.
Typical load balancing traffic flow
The following steps comprise the typical load balancing traffic flow for NetScaler:
1. A user enters a URL into their browser.
2. The URL's Domain Name Server (DNS) record points to one of the public Virtual Internet Protocols (VIP) on NetScaler and identifies the traffic's protocol (such as HTTP port 80 traffic).
3. NetScaler then passes that traffic to one of the servers in the server pool, based on the balancing method defined (such as round robin, persistence, and so on).
4. The servers send back the page or application that the user requested by using a Load Balancing Virtual IP (LBVIP).
5. The LBVIP routes the traffic to the Internet by setting the source to LBVIP.
6. The web page or application displays on the user computer.
The following image shows this traffic flow:
Prerequisites
Before configuring NetScaler load balancing, perform the following steps:
1. Load the necessary license to NetScaler.
2. Configure the `MGMT` port for management access.
3. Configure DNS servers and the Subnet IP Address (SNIP) in the same server subnet
and allow the Virtual Local Area Network (LAN) in the switch trunk port that
is connected to NetScaler.
Configuration
To configure NetScaler load balancing, perform the following steps:
To add the backend servers, perform the following steps:
1. Connect to the management IP of your NetScaler.
2. Select Login > Configuration > Traffic Management > Load Balancing > Servers.
3. Click Add.