The allowable recovery rules are:

• none

• immediate

• time-day-window

The way the immediate rule operates depends on the type of server the gateways are registered to. If the following conditions are met, the gateways can reregister to the main server after the network stability period expires:

• The survivable server is Survivable Core Server (SCS).

• There are gateways registered with the main server.

The default duration of the network stability period is three minutes. You can change the duration on the mg-recovery-rule screen. If all the gateways are on SCS, then the network regions assigned to the survivable server are disabled. If the survivable server is Survivable Remote Server (SRS), then the network regions are disabled even if there are some telephones and gateways registered with the main server.

If you administer the time-day-window (TDW) rule, all the associated network regions are disabled regardless of the type of the survivable server. When the TDW day and hour is reached, the system activates the NRs, and all the gateways and telephones in those NRs return to the main server. At the end of the hour, the system checks whether all the gateways have returned. If the gateways have returned to the main server, the system reactivates the feature for the next event. If not, the NRs are disabled, causing all the gateways to register with the survivable server.

With the enable mg-return command, you can re-register gateways to the server. If some gateways remain unregistered from the main server in the active state and the survivable server in the active state, the system again disables the network regions. If the survivable server deregisters from the main server, the main server does not receive information about the status of the survivable server. If the main server does not receive information about the status of the survivable server, the main server activates all the network regions associated with the survivable server.