10.1.8.1. Feature Description 
Dependability checks during normal operation mode every minute the
status of the LAN connections to the configured APs. If the check detects
that no configured AP is connected and several conditions (see Section 1.8.2,
“Service Information” > Conditions for switchover)
are fulfilled, a switchover is triggered to try whether the BP can establish
LAN connections to the APs.
In this implementation the BP is not asked before the switchover
whether LAN connections to the APs are possible. Instead one switchover
is triggered and then it is checked at the new active BP whether LAN
connections can be established now. If not, then another switchover will
be triggered back to the originally active BP.
If a BP successfully sets up a LAN connection to an AP, the LAN monitoring
feature is reinitialized on this BP so as to enable a further switchover
should all AP connections be lost again.
Special situations
- There is a special situation when
EXEC-USSU:UPDATAP;is executed. In this scenario the LAN connections to all APs are stopped and restarted. This could trigger a switchover because all conditions of the LAN monitoring feature are fulfilled. Therefore dependability checks for this update scenario to avoid an unnecessary switchover. - If the AMO command
RES-USSU:ALLE;is executed, all APs will be reset. In order to ensure that there is no undesired switching in this scenario also, a switchover delay of 1 minute was integrated after which the switchover conditions are tested again. It is only then if these conditions are still fulfilled that the switchover is started.