Nortel DMS-100 Series Maintenance Manual page 106

1-90 Maintenance overview
The A-shelf is automatically or manually protection switched and the A-link
is manually busied. When this condition occurs, the protection link remains
switched to the A-shelf. Refer to scenario 3.
Scenarios of manually busy, switched primary links
Scenario 1:
The C-shelf is protection switched because of a defective C-link. Faults are
not present on any other primary link.
Scenario 2:
The C-shelf is manually protection switched.
Scenario 3:
The A-shelf is protection switched because of a defective A-link. Faults are
not present on any other primary link.
Operational considerations
The following list covers important items for protection switching:
297-8231-550 Standard 09.01 August 1998
The C-link is manually busied.
The protection link is released.
The C-link is manually busied.
The protection link is not released. The protection link is switched for
the C-shelf.
The A-link is manually busied.
The protection link remains switched on the A-shelf.
If a ManB primary link is protection switched, the FORCE option must
be used to RTS the link. When the RTS command is used without the
FORCE option, DS-1 diagnostics are run on the link. These diagnostics
fail when the link is protection switched. If the DS-1 diagnostics fail,
the link is not returned to service. The use of the FORCE option
bypasses diagnostics.
When an RCS request causes a protection switch, the CARRIER level of
the MAP display indicates the primary link is protection switched. The
system generates a log. The log indicates that the far end (RCS) initiated
the protection switch.
Protection switching status can be queried at the PM level of the MAP
display. Post the RCS and enter the command string QUERY PM FLT.
A message appears that indicates the far end (RCS) initiated the
protection switch.