Product Documentation

Configuring URL Passive Persistence

Nov 23, 2015

With URL Passive persistence, when the NetScaler appliance receives a request from a client, it extracts the server IP address-port information (expressed as a single hexadecimal number) from the client request.

URL passive persistence requires configuring an advanced expression that specifies the query element that contains the server IP address-port information. For more information about classic and advanced policy expressions, see Policy Configuration and Reference.

The following expression configures the appliance to examine requests for URL queries that contain the string "urlp=", extract the server IP address-port information, convert it from a hexadecimal string to an IP and port number, and forward the request to the service configured with this IP address and port number.

HTTP.REQ.URL.AFTER_STR(“urlp=”)

If URL passive persistence is enabled and the above expression is configured, a request with the following URL and server IP address-port string is directed to 10.102.29.10:80.

http://www.example.com/index.asp?&urlp=0A661D0A0050

The persistence time-out value does not affect this persistence type; persistence is maintained as long as the server IP address-port information can be extracted from client requests. This persistence type does not consume any NetScaler resources, so it can accommodate an unlimited number of persistent clients.

To configure URL passive persistence, you first configure persistence as described in Configuring Persistence Types That Do Not Require a Rule. You set the persistence type to URLPASSIVE. You then perform the procedures provided below.

To configure URL passive persistence by using the command line interface

At the command prompt, type:

set lb vserver <vserverName>  [-persistenceType <persistenceType>]  [-rule <expression>]

Example

set lb vserver LB-VServer-1 -persistenceType URLPASSIVE –rule HTTP.REQ.URL.AFTER_STR(“urlp=”)

To configure URL passive persistence by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers, and open the virtual server.
  2. In Advanced Settings, select Persistence, and specify URLPASSIVE.