Nortel DMS-100 Series Maintenance Manual page 107

Maintenance overview 1-91
Call processing cannot proceed over a protection link if the protection
link is switched for a manually busy primary link.
The SMS detects a fault and a protection switch occurs. The CARRIER
level of the MAP display indicates that the primary link is protection
switched. The CARRIER level of the MAP display also indicates the
type of DS-1 fault like LCGA, BPV OOS. The system generates a log.
The log indicates that the near-end SMS initiated the protection switch.
To query protection switching status at the PM level of the MAP display,
post the RCS. Enter the command string . The system
>QUERYPM FLT
displays a message that indicates the near-end SMS initiated the
protection switch.
The RCS detects a fault that results in a protection switch. The A- and
B-bits received from the RCS cannot be determined for up to 120 ms.
A fault is present on the protection link toward the RCS (RCS protection
link receive side). A fault is also present on the A-link toward the SMS.
No other faults are present on the A-link or protection link. The SMS
executes a protection switch to the A-link and one-way transmission
from the shelf occurs.
The SMS receives a minor alarm from the RCS. The protection link and
the A-link remain INSV. The minor alarm is received from the RCS and
the A-shelf is protection switched because of SMS fault detection. The
protection line must be checked for faults.
The system generates logs when a protection line switch or release
occurs.
The system generates logs when a primary link is enabled or disabled for
protection switching. Logs indicate the type of switch (automatic or
manual) and which end (RCS or SMS) initiated the switch.
The PM level of the MAP terminal can display shelf alarm status and
protection switching status for a particular RCS.
The CARRIER level of the MAP display shows the DS-1 link status.
The CARRIER level of the MAP display indicates any protection switch
for a given set of DS-1 links.
Maintenance personnel can perform manual protection switching
commands at the CARRIER level of the MAP terminal.
DMS-100 Family SMS Maintenance Manual XPM10 and up