The auto fallback to primary controller feature automatically returns a fragmented network, in which a number of Branch Gateways are being serviced by one or more survivable remote servers, to the primary server. This feature is targeted towards all Branch Gateways. By migrating the gateways back to the primary automatically, the distributed telephony switch network can be made whole sooner without human intervention.
The auto fallback migration, in combination with the connection preservation feature for H.248 gateways is connection preserving. Stable connections are preserved, while unstable connections, such as ringing calls, are not preserved. A very short interval without dial tone can still exist for new calls.
The gateway presents a new registration parameter that indicates that Service is being obtained from a survivable remote server. The parameter indicates the number of active user calls on the gateway platform. The server administers each gateway with a set of rules for Time of Day migration, enable or disable, and the setting of call threshold rules for migration.
Using this feature, the administrator can define any of the following rules for migration:
The gateway must migrate to the primary automatically or not.
The gateway must migrate immediately when possible, regardless of active call count.
The gateway must only migrate if the active call count is 0.
The gateway must only migrate within a window of opportunity by providing day of the week and time intervals per day. This option does not take call count into consideration.
The gateway should be migrated within a window of opportunity by providing day of the week and time of day, or immediately if the call count reaches 0. Both rules are active at the same time.
Internally, the primary call controller gives priority to registration requests from the gateways that are currently not being serviced by an survivable remote server. This priority is not administrable.
An auto-fallback can be denied for several reasons, which can result from general system performance requirements or from administrator-imposed requirements. General system performance requirements can include denial of registration because of too many simultaneous gateway registration requests.
Administrator-imposed requirements for denial of a registration can include:
Registrations restricted to a windowed time of day.
Migration restricted to a condition of 0 active calls, that is, there are no users on calls within the gateway in question.
The administered minimum time for network stability has not been exceeded.
This feature does not preclude an older gateway firmware release from working with Communication Manager 10.x or vice versa. However, the auto-fallback feature is not available.
For this feature to work, the call controller is required to have Communication Manager, while the gateway is required to have the gateway firmware available at the time of the Communication Manager 10.x release.
Existing branch gateways are the targets.
For each gateway, the following administration must be performed:
