Secure Mobile Access 12.4 CMS Administration Guide

How a Standby Appliance Works

If the active appliance fails, and the CMS continues to be in service:

  • The standby appliance is activated and will accept new connections that are made to the GTO service name
  • The administrator is notified through an alert on the console.

However, if the CMS fails and the active appliance continues to be in service, the standby appliance will not be activated.

If the both CMS and the active appliance fail:

  • The standby appliance will be activated and will accept new connections made to the GTO service name
  • If the active appliance is undergoing maintenance by the CMS (such as for a configuration change, hotfix installation, or firmware upgrade), and user connections cannot be serviced, the standby appliance will be automatically activated.

When a standby appliance gets activated:

  • Existing user sessions from any failed appliances may be resumed on the newly activated appliance and will be allowed to continue until the sessions are either terminated by users or by timing out.
  • SMA clients, such as Connect Tunnel and Mobile Connect, will detect a connection failure and automatically reconnect to the GTO service.
  • Web-based client applications will reconnect to the standby appliance when users refresh the browser window.
  • ActiveSync client requests will get directed to the standby appliance.

Using a Configuration Extension Mechanism (CEM) will allow for a quicker activation of standby appliances by the CMS when the CMS is unable to communicate with the active SMA appliances.

Without the CEM, a standby appliance is guaranteed to activate 10 - 15 minutes after all designated GTO appliances lose communication with the Standby appliance.

Using the CEM may result in a standby appliance becoming active more frequently in situations where transient network glitches interfere with CMS communication with appliances.

  • The CEM will have an effect only when applied to a CMS with GTO enabled and configured with at least one standby appliance.
  • The CEM value should be an integer that represents the number of minutes after which communication is continually lost with all designated GTO appliances a standby appliances becomes active.

    • When the CEM value is in the range 11 - 15, a standby appliance may become active sooner than the CEM value specifies, possibly as quickly as 10 minutes after a disaster begins.

    • The CEM has no effect if the value is outside the range 0 - 15, or if the value is not an integer.

  • When the CEM is in use, a standby appliance that is in communication with the CMS is guaranteed to become active a maximum of X minutes (where X is the value specified for the CEM) after the CMS detects that it cannot communicate with all of the designated GTO appliances.

  • If the CMS becomes disconnected from an appliance during a disaster, the CEM will have no effect on the appliance.

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