Product Documentation

Enabling Load Balancing Virtual Servers to Redirect Requests to Cache

Aug 23, 2013

If a load balancing virtual server is configured to listen on a particular IP address and port combination, it takes precedence over the cache redirection virtual server for any requests destined for that address-port combination. Therefore, the cache redirection virtual server does not process those requests.

If you want to override this functionality and let the cache redirection virtual server decide whether the request should be served from the cache or not, configure the particular load balancing virtual server to be cacheable.

Such a configuration is typically used when an ISP uses a NetScaler appliance at the edge of its network and all traffic flows through the appliance.

To enable load balancing virtual servers to redirect requests to the cache by using the command line interface

At the command prompt, type:

  • set lb vserver <name> [-cacheable ( YES | NO)]
  • show lb vserver [<name>]

Example

 
set lb vserver Vserver-LB-CR –cacheable YES 
> show lb vserver vserver-LB-CR 
        Vserver-LB-CR (10.102.20.30:80) - HTTP  Type: ADDRESS 
        State: DOWN 
        Last state change was at Fri Jul  2 08:47:52 2010 
        Time since last state change: 0 days, 01:05:51.510 
        Effective State: DOWN 
        Client Idle Timeout: 180 sec 
        Down state flush: ENABLED 
        Disable Primary Vserver On Down : DISABLED 
        Port Rewrite : DISABLED 
        No. of Bound Services :  1 (Total)       0 (Active) 
        Configured Method: LEASTCONNECTION 
        Mode: IP 
        Persistence: NONE 
        Cacheable: YES  PQ: OFF SC: OFF 
        Vserver IP and Port insertion: OFF 
        Push: DISABLED  Push VServer: 
        Push Multi Clients: NO 
        Push Label Rule: none 
 
1) Service-HTTP-1 (10.102.29.40: 80) - HTTP State: DOWN Weight: 1 
 Done 

For transparent cache redirection, the NetScaler intercepts all traffic and evaluates every request to determine whether it is cacheable. Non-cacheable requests are sent unchanged to the origin server.

When using transparent cache redirection, you may want to turn off cache redirection for load balancing virtual servers that always direct traffic to origin servers.

To turn off caching for a load balancing virtual server by using the command line interface

To turn off caching for a load balancing virtual, use the unset lb vserver command instead of set lb vserver. Specify a value of NO value for the -cacheable parameter.

To enable or disable load balancing virtual servers to redirect requests to the cache by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers.
  2. In the details pane, select the virtual server from which you want to enable/disable the caching, and then click Open.
  3. On the Advanced tab, select/clear Cache Redirection check box.
  4. Click OK.