Nortel DMS-100 Series Maintenance Manual page 52

1-36 Maintenance overview
If the SWACT controller denies a manual request for a SWACT, you receive
this information. You receive a reason for the denial. The message informs
you that you can enter the SWACT FORCE command to override the
SWACT controller. If you decide to override the SWACT controller, the
system attempts a WARM SWACT. The system does not consult diagnostic
history or state data. The active unit of the XPM drops activity. The active
unit becomes the inactive unit. This unit remains in-service until the new
active unit verifies two-way communication with the CM. The new active
unit verifies the ability to maintain activity.
If two-way communication is available and the new active unit can maintain
activity, the inactive unit becomes system busy. The inactive unit returns to
service. If communication fails or the new active unit cannot maintain
activity, a SWACT back to the original active unit occurs. Refer to the
following figure for an example of a SWACT back.
For controlled and uncontrolled SWACTs, the SWACT is complete when the
CC receives a gain message from the new active unit. The CC
acknowledges the gain to the original active unit. When a SWACT occurs,
the CC and the SMS exchange a series of drop and gain messages that
describe activity. The following table describes common phrases found in
these messages.
Message phrases that describe CC to SMS SWACT communication
Message phrase
Original active unit
Original inactive unit
New active unit
New inactive unit
Gain message
Gain acknowledge
message
Gain acknowledge
received
Drop message
During a SWACT back, the original active unit attempts to regain activity.
If successful, the inactive unit becomes system busy and returns to service.
The active unit remains in service. The system maintains calls that have
297-8231-550 Standard 09.01 August 1998
Explanation
Active unit before the SWACT (unit 0)
Inactive unit before the SWACT (unit 1)
Active unit after the SWACT (unit 1)
Inactive unit after the SWACT (unit 0)
The message the new active unit (unit 1) sends to the
CC to inform the CC that unit 1 gains activity
The message the CC sends to original active unit to
confirm the new active unit sends messages
Message original active unit sends to CC to confirm
the new active unit passed the post-SWACT audit
Message the original active unit (unit 0) sends to the
CC to inform the CC that unit 0 dropped activity