Selecting a switching mode and clicking the Apply button at the
bottom of the screen enables the switching mode in the selected
device.
UPSR protection switching
priorities
Metropolis
®
DMXplore uses standard UPSR protection switching
priorities as follows:
•
Lockout of protection: switches to side 1 (if not already there)
and prevents further protection switching.
•
Forced switch: selects the requested ring path and prevents
further protection switching.
•
Automatic switch - signal fail: Metropolis
®
DMXplore uses
optional SONET 1+1 unidirectional, nonrevertive automatic line
protection switch (APS) procedures. After a cut service fiber is
repaired, a location does not switch back (revert) to the line/port
that was originally active. Rather, service remains active on the
path that is currently active.
A signal fail (SF) is declared for incoming loss of signal (LOS),
loss of frame (LOF), loss of pointer (LOP), path unequipped, line
AIS, BER exceeding 10
-3
(default), 10
-4
, or 10
-5
for STSN
signals, or BER exceeding 10
-3
for VT signals.
•
Automatic switch - signal degrade: Automatic line switches are
initiated by signal fail and signal degrade conditions received on
the STSN or VT signal. This signal’s bit error rate (BER) is
calculated from violations in the SONET path overhead: B3 for
STSN and V5 for VT. A line protection switch is completed
within 60 milliseconds of the onset of a hard failure such as a
fiber cut. A signal degrade condition is declared on STSN signals
with a BER exceeding a provisionable 10
-5
to 10
-9
threshold and
on VT signals with a BER exceeding a provisionable 10
-5
to 10
-8
threshold. (10
-6
is the default for STSN and VT.)
•
Manual switch: selects the requested ring path provided the
requested ring path is good and there are no existing protection
switching requests in place.
•
Reset: clears an existing lockout, force, or manual switch.
Protection switching
Maintenance overview
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4 - 1 2
Lucent Technologies
365-372-333 R2.1
Issue 4, June 2005