Manage client connections for a virtual server

You can configure timeouts on a cache redirection virtual server so that client connections are not kept open indefinitely. You can also insert Via headers in requests. To possibly reduce network congestion, you can reuse open TCP connections. You can enable or disable delayed cleanup of cache redirection virtual server connections.

You can configure the appliance to send ICMP responses to PING requests according to your settings. On the IP address corresponding to the virtual server, set the ICMP RESPONSE to VSVR_CNTRLD, and on the virtual server, set the ICMP VSERVER RESPONSE.

The following settings can be made on a virtual server:

  • When you set ICMP VSERVER RESPONSE to PASSIVE on all virtual servers, appliance always responds.
  • When you set ICMP VSERVER RESPONSE to ACTIVE on all virtual servers, appliance responds even if one virtual server is UP.
  • When you set ICMP VSERVER RESPONSE to ACTIVE on some and PASSIVE on others, appliance responds even if one virtual server set to ACTIVE is UP.

This document includes the following information:

  • Configure client timeout

  • Insert Via headers in the requests

  • Reuse TCP connections

  • Configure delayed connection cleanup

Configure client timeout

You can specify expiration of client requests by setting a timeout value for the cache redirection virtual server. The timeout value is the number of seconds for which the cache redirection virtual server waits to receive a response for the client request.

To configure a time-out value, use the cltTimeout parameter, which specifies the time, in seconds, after which the NetScaler appliance closes any idle client connections. The default value is 180sec for HTTP/SSL-based services and 9000sec for TCP-based services.

Configure client timeout by using the CLI

At the command prompt, type the following commands to configure client timeout and verify the configuration:

-  set cr vserver <name> [-cltTimeout <secs>]
-  show cr vserver <name>

Example:

> set cr vserver Vserver-CRD-1 -cltTimeout 6000
 Done
> show cr vserver Vserver-CRD-1
        Vserver-CRD-1 (*:80) - HTTP     Type: CONTENT
        State: UP  ARP:DISABLED
        Client Idle Timeout: 6000 sec
        Down state flush: ENABLED
        Disable Primary Vserver On Down : DISABLED
        Default:        Content Precedence: URL Cache: TRANSPARENT
        On Policy Match: CACHE  L2Conn: OFF     OriginUSIP: OFF
        Redirect: POLICY        Reuse: ON       Via: ON ARP: OFF
        Backup: Vserver-CRD-2

1)      Cache bypass  Policy: bypass-cache-control
2)      Cache bypass  Policy: Policy-CRD
 Done

Configure client timeout by using the GUI

  1. Navigate to Traffic Management > Cache Redirection > Virtual Servers.
  2. In the details pane, select the virtual server for which you want to configure client timeout, (for example, Vserver-CRD-1), and then click Open.
  3. In Configure Virtual Server (Cache Redirection) dialog box, select the Advanced tab.
  4. In the Client Time-out(secs) text box, enter the time-out value in seconds.
  5. Click OK.

Insert Via headers in the requests

A Via header lists the protocols and recipients between the start and end points for a request or a response and informs the server of proxies through which the request was sent. You can configure the cache redirection virtual server to insert a Via header in each HTTP request. The via parameter is enabled by default when you create a cache redirection virtual server.

To enable or disable Via-header insertion in client requests, use the via parameter, which specifies the state of the system in inserting a Via header in the HTTP requests.

Possible values: ON, OFF

Default value: ON

Enable or disable Via-header insertion in client requests by using the CLI

At the command prompt, type:

-  set cr vserver <name> [-via (ON|OFF)]
-  show cr vserver <name>

Example:

> set cr vserver Vserver-CRD-1 -via ON
 Done
> show cr vserver Vserver-CRD-1
        Vserver-CRD-1 (*:80) - HTTP     Type: CONTENT
        State: UP  ARP:DISABLED
        Client Idle Timeout: 6000 sec
        Down state flush: ENABLED
        Disable Primary Vserver On Down : DISABLED
        Default:        Content Precedence: URL Cache: TRANSPARENT
        On Policy Match: CACHE  L2Conn: OFF     OriginUSIP: OFF
        Redirect: POLICY        Reuse: ON       Via: ON ARP: OFF
        Backup: Vserver-CRD-2

1)      Cache bypass  Policy: bypass-cache-control
2)      Cache bypass  Policy: Policy-CRD
 Done
>

Enable or disable Via-header insertion in client requests by using the GUI

  1. Navigate to Traffic Management > Cache Redirection > Virtual Servers.
  2. In the details pane, select the virtual server for which you want to configure client timeout, (for example, Vserver-CRD-1), and then click Open.
  3. In Configure Virtual Server (Cache Redirection) dialog box, select the Advanced tab.
  4. Select the Via check box.
  5. Click OK.

Reuse TCP connections

You can configure the NetScaler appliance to reuse TCP connections to the cache and origin servers across client connections. This can improve performance by saving the time required to establish a session between the server and the appliance. The reuse option is enabled by default when you create a cache redirection virtual server.

To enable or disable the reuse of TCP connections, use the reuse parameter, which specifies the state of reuse of TCP connections to the cache or origin servers across client connections.

Possible values: ON, OFF

Default value: ON

Enable or disable the reuse of TCP connections by using the CLI

At the command prompt, type:

-  set cr vserver <name> [-reuse (ON|OFF)]  
-  show cr vserver <name>  

Example:

> set cr vserver Vserver-CRD-1 -reuse ON
 Done
> show cr vserver Vserver-CRD-1
        Vserver-CRD-1 (*:80) - HTTP     Type: CONTENT
        State: UP  ARP:DISABLED
        Client Idle Timeout: 6000 sec
        Down state flush: ENABLED
        Disable Primary Vserver On Down : DISABLED
        Default:        Content Precedence: URL Cache: TRANSPARENT
        On Policy Match: CACHE  L2Conn: OFF     OriginUSIP: OFF
        Redirect: POLICY        Reuse: ON       Via: ON ARP: OFF
        Backup: Vserver-CRD-2

1)      Cache bypass  Policy: bypass-cache-control
2)      Cache bypass  Policy: Policy-CRD
 Done

Enable or disable the reuse of TCP connections by using the GUI

  1. Navigate to Traffic Management > Cache Redirection > Virtual Servers.
  2. In the details pane, select the virtual server for which you want to configure client timeout, (for example, Vserver-CRD-1), and then click Open.
  3. In Configure Virtual Server (Cache Redirection) dialog box, select the Advanced tab.
  4. Select the Reuse check box.
  5. Click OK.

Configure delayed connection cleanup

The down state flush option performs delayed cleanup of connections on a cache redirection virtual server. The down state flush option is enabled by default when you create a cache redirection virtual server.

To enable or disable the down state flush option, set the downStateFlush parameter.

Possible values: ENABLED, DISABLED

Default value: ENABLED

Enable of disable the down state flush option by using the CLI

At the command prompt, type the following commands to configure delayed connection clean up and verify the configuration:

-  set cr vserver <name> [-downStateFlush (ENABLED | DISABLED)]
-  show cr vserver <name>

Example:

> set cr vserver Vserver-CRD-1 -downStateFlush ENABLED
 Done
> show cr vserver Vserver-CRD-1
        Vserver-CRD-1 (*:80) - HTTP     Type: CONTENT
        State: UP  ARP:DISABLED
        Client Idle Timeout: 6000 sec
        Down state flush: ENABLED
        Disable Primary Vserver On Down : DISABLED
        Default:        Content Precedence: URL Cache: TRANSPARENT
        On Policy Match: CACHE  L2Conn: OFF     OriginUSIP: OFF
        Redirect: POLICY        Reuse: ON       Via: ON ARP: OFF
        Backup: Vserver-CRD-2

1)      Cache bypass  Policy: bypass-cache-control
2)      Cache bypass  Policy: Policy-CRD
 Done

Enable or disable the reuse of TCP connections by using the GUI

  1. Navigate to Traffic Management > Cache Redirection > Virtual Servers.
  2. In the details pane, select the virtual server for which you want to configure client timeout, (for example, Vserver-CRD-1), and then click Open.
  3. In Configure Virtual Server (Cache Redirection) dialog box, click Advanced tab.
  4. Select the Down state flush check box.
  5. Click OK.

Manage client connections for a virtual server