• Secure Mobile Access 12.4
• About This Guide
• CMS Configuration
  • Introduction to CMS
    • Overview
    • CMS Deployment Options
    • What’s New in This Release
      • Global Policy Settings
      • CMS Alerts Logging
    • Central Management Server
    • Central Management Console
    • Managed Appliances
    • Licensing CMS
    • Central User Licenses
    • Global Traffic Optimizer
    • FIPS and CMS
    • Getting Started in Five Steps
  • Installing and Configuring the Central Management Server
    • Overview
    • Kernel based Virtual Machine
    • Supported Platforms for CMS with Global HA
    • Hardware Resource Requirements
    • Installation Files
    • Setting Up a CMS
  • Configuring Appliances for Central Management
    • Overview
    • Firmware Compatibility with the CMS
    • Enabling Central Management on SMA Appliance
    • Registering an SMA Appliance with the CMS
    • Previously Configured Appliances
  • Using the Management Console Menus
    • Overview
    • Dashboard
      • Alerts
      • Appliances Pane
      • Appliance Load
      • Central License Usage Pane
      • About Pane
    • Management Server
      • Alerts
        • View Alerts
        • Configure Alerts
        • Notification
      • Configure
        • Central Management Settings
        • CMS Address Pool
        • Licensing
        • Administrators
          • General Settings
        • Network Settings
        • SSL Settings
        • Services
          • Manage SSH settings from CMS
      • Monitor
        • Configure the logging setting for Managed appliances
      • Maintain
    • Managed Appliances
      • Add/Remove
      • Configure
        • Overview
        • Configuring the Managed Appliances
          • Define Policy
          • Synchronize
        • Support multiple policies with CMS and shared licensing
          • Applying authentication servers to specific appliance
          • Applying SMTP configuration service to specific appliance
          • Applying SMS service to specific appliance
          • Applying realms to a subset of appliance
          • Assign rules to a subset of appliances
          • Support multiple GTO services
      • Monitor
        • User Sessions
        • Reports
        • Health
      • Maintain
  • Central User Licensing
    • Overview
    • How Central User Licenses Work
      • Central Spike User Licenses
      • Central Email Licenses
      • Perpetual Pooled Licenses
    • Enabling Central User Licensing
    • Getting Started with Central User Licensing
      • Setting Up CMS to Use Central User Licenses
      • Setting up CMS for Centralized Appliance Configuration and Management
      • Resetting a CMS License
  • Global High Availability
    • High Availability of the VPN Service
    • High Availability of the CMS
    • Disaster Recovery for the VPN Service
  • Alerts and SNMP
    • Overview
    • Pre-Configured Alerts
    • Configuring SNMP
  • Capture Advanced Threat Protection
    • Enabling Capture ATP
    • File Options
    • Web Services
    • Advanced Settings
  • Central FIPS Licensing
• Global High Availablity
  • Introduction to Global HA and GTO
  • Planning GTO Deployment
    • Choosing a Deployment Model
    • Minimizing Configuration Differences
    • GTO Service Names and DNS Delegations
    • Provisioning Certificates
      • Let's Encrypt
      • Adding Certificates to SMA Appliances
      • Generating a Certificate Signing Request (CSR)
      • Importing SSL Certificates
  • Setting up GTO
    • Setting up the CMS and SMA appliances
    • Enabling GTO service for managed appliances with the CMS
    • Setting up a Basic GTO Service
    • Monitoring and Configuring GTO
    • Defining the Central Policy
  • Extending GTO Deployment
    • Enabling Cached Credentials
    • Additional Deployment Notes
• SonicWall Support
  • About This Document

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 name will be MGMT_STANDBY_APPLIANCE_ACTIVATION_MINUTES.

• 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.