Nortel DMS-100 Series Maintenance Manual page 103

Scenario 4
The C-shelf is manually protection switched. Faults are not present on any
primary link. The protection link is INSV.
A fault is detected on the B-link.
The protection link remains switched to the C-shelf. The B-shelf is
system busied.
Scenario 5
The A-shelf is defective. Faults are not present on any other primary link.
The protection link is INSV.
A manual switch request is issued for the B-shelf.
The manual switch request fails because of a loss of the DDL caused by
the defective A-shelf.
Scenario 6
The A-shelf is manually protection switched. Faults are not present on any
DS-1 link.
A manual release of the protection link is requested.
The protection link is released from the A-shelf.
Scenario 7
The C-shelf is manually protection switched. Faults are not present on any
primary links. The protection link is INSV.
A manual switch to the B-shelf is requested.
The protection link drops from the C-shelf and switches to the B-shelf.
Manual protection link release
You can manually release manual or automatic protection switches. The
primary link can have a defect and the protection link is released. The
protection link immediately switches back to the defective primary link
when this condition occurs. Refer to scenario 1.
The protection link can release when the primary link is not defective.
When this condition occurs, the protection link is switched for any other
primary link with a fault. Refer to scenarios 2 and 3. If a defective primary
link is not permanently switched, you must disable protection switching for
that primary link.
DMS-100 Family SMS Maintenance Manual XPM10 and up
Maintenance overview 1-87