The emergency group is the logical connecting link between the access point/OpenScape 4000 SoftGate and CC-AP/Survivable OpenScape 4000 SoftGate.

An access point/OpenScape 4000 SoftGate is a member of exactly one emergency group. An emergency group is served by exactly one CC-AP/Survivable OpenScape 4000 SoftGate.

The emergency group was introduced for transferring complete groups of access points/OpenScape 4000 SoftGates, together and at the same time, to and from the host system control to the CC-AP/Survivable OpenScape 4000 SoftGate control.

While the primary function of the AP Emergency feature is handling the total breakdown of the central control, the difficulty lies in appropriate handling of partial breakdowns that may arise in the IP communication.

An emergency group typically combines access points/OpenScape 4000 SoftGates that together form a survivable unit. For example, this could be external location connected via WAN.

Faults in the routing can result in only some of a group’s access points/OpenScape 4000 SoftGates losing contact with the central control. In this case it would be possible to transfer only the affected access points/OpenScape 4000 SoftGates to the CC-AP/Survivable OpenScape 4000 SoftGate control. This interrupts communication among the group’s access points/OpenScape 4000 SoftGates, however. Calls would then only be possible via the trunk. But does each access point/OpenScape 4000 SoftGate have its own trunk line? Where are the central resources, such as recorded announcements, servers, etc.?

This is why it often makes sense to switch a group only as a whole. In this way all access point/sOpenScape 4000 SoftGates remain under one control, and communication among the access points/OpenScape 4000 SoftGates runs via IP. All access points/OpenScape 4000 SoftGates can communicate with the rest of the system via a common trunk line. In such cases, the access points/OpenScape 4000 SoftGates of one emergency group will also belong to one source group for source-dependent routing (see “IP Distributed Architecture”, Section 2.8, “Source Dependent Routing”).

An emergency group is identified by a freely selectable number. Depending on the installation, it may be advantageous to base the emergency group number on the numbering of the associated source group or the CC-AP/Survivable OpenScape 4000 SoftGate number.

Because plain text says more than any number, no matter how cleverly selected, you can give each emergency group a name.

Each configured emergency group must be assigned to a CC-AP/Survivable OpenScape 4000 SoftGate. The assignment can be changed.

Weighting determines whether all of an emergency group’s access points/OpenScape 4000 SoftGates switch to the CC-AP/Survivable OpenScape 4000 SoftGate. A weighting is assigned to each access point/OpenScape 4000 SoftGate. The access point/OpenScape 4000 SoftGate contributes this weighting to the switching evaluation in the event of a breakdown in its connection to the central control. A limiting value can be defined for the group. When this value is exceeded, a switchover is carried out.

Because they have higher weightings, access points/OpenScape 4000 SoftGates with trunk lines, central resources or VIP users are more likely to trigger a switchover than access points/OpenScape 4000 SoftGates with “standard features“.

When assigning the weightings, you must make sure that the weighting of all access points/OpenScape 4000 SoftGates that are assigned to an emergency group is sufficient in order to reach the group’s limiting value. This is easy to overlook, particularly when you are changing the configuration.

If the IP connections to central control are available again for all access points/OpenScape 4000 SoftGates, switchback to central control must be organized. There will be customers who require immediate switchback to the central control, even though this means disconnecting calls. Often, however, switchback is prohibited at certain times. It may also be the case that only administrative switchovers are permitted.

AP Emergency enables the activation of either automatic switchback, or of only manual switchback. The parameters for automatic switchback are based on the level of the emergency groups.

For the group - and therefore for all access points/OpenScape 4000 SoftGates in the group - you can stipulate how long the connection between each access point/OpenScape 4000 SoftGate and the central control must be stable without interruptions, before a switchback will be considered.

Once the connection has been stable for the specified length of time, a check is made as to whether a switchback is allowed at the time. Intervals during which a switchback is permitted are set up for this purpose. The interval starts with the specified hour (of the day) and ends at another specified hour. It is customary to set up a time offset in order to shift the network load of scheduled activities away from the exact hour. This allows you to specify how many minutes after the hour the switchback interval is opened or closed. For example, if the switchback start is at 8pm, the switchback end at 6am, and the offset is 13, this means that the switchback can automatically take place during the time from 8:13pm and 6:13am. If there was a network fault in this configuration that interrupted the IP connection between the central control and the access points/OpenScape 4000 SoftGates from 9:05am until 9:15am, the automatic switchback would take place at 8:13pm. If the fault occurs during the switchback interval, the switchback takes place immediately once the IP connections between the central control and access points/OpenScape 4000 SoftGates have been stable again for the minimum time.

A manual switchback is possible at any time. The administrator must ensure here that the boundary conditions are correct (is switchback required? - are all access points/OpenScape 4000 SoftGates connected to the central control unit again?).

If a CC-AP/Survivable OpenScape 4000 SoftGate fails while it is actively controlling access points/OpenScape 4000 SoftGates, the following behavior results:

ADD-APESU:DATA=APEGRP,EGRPNO=2,CCAPNO=99,THRSHLD=100,SB­
MODE=,NAME=“BERLIN“,STABLE=10,SBBEGIN=20,SBEND=6,RSOFFSET=13;

CHANGE-APESU:DATA=APEGRP,EGRPNO=2,CCAPNO=99,THRSHLD=100,SBMODE=AU­
TO,NAME=“BERLIN“,STABLE=10,SBBEGIN=20,SBEND=6,RSOFFSET=13;

The modified data does not take effect until after you have used OpenScape 4000 Assistant Backup & Restore to copy the database to the CC-AP/Survivable OpenScape 4000 SoftGate, and the CC-AP/Survivable OpenScape 4000 SoftGate has accepted it.