Protection Switching - Nortel NTRN10AN Planning Manual

2-118 Operation, administration, and maintenance (OAM) features

Protection switching

At the OC-48 line rate, an optical fiber cut could result in 1344 VT1.5s being
switched to an alternate path. The system is required to meet the 60-ms switch
time for multiple path failures on a single optical interface only.
For more information about protection switching behaviour for specific circuit
packs:
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The Wait to Restore time and Signal Degrade Threshold are provisionable for
OC-48 and OC-192 optical interface pairs and DS1 circuit packs.
On BLSR rings, user-initiated switches are supported as follows:
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OPTera Metro 3500 Multiservice Platform
OC-192 optical interface circuit pack on page 3-59
OC-48 optical interface circuit pack on page 3-65
OC-48 STS optical interface circuit pack on page 3-68
OC-12 optical interface circuit pack on page 3-72
OC12x4 STS IR optical interface circuit pack on page 3-75
OC-3 optical interface circuit pack on page 3-77
OC-3x4 optical interface circuit pack on page 3-80
EC-1x3 circuit pack on page 3-82
EC-1x12 circuit pack on page 3-84
DS1 mapper on page 3-86
DS3x3 mapper on page 3-87
DS3x12 / DS3x12e mapper on page 3-89
DS3VTx12 mapper on page 3-90
Note 1: If multiple simultaneous path failures, such as an optical fiber cut,
occur on different optical interfaces such as an OC-3, OC-12, OC-48 or
OC-192, the 60 ms switch time may not be met. Protection of simultaneous
path failures on multiple OC-n optical interfaces will complete in less than
200 ms.
Note 2: VT1.5 management is not supported on OPTera Metro 3500
shelves equipped with STX-192 circuit packs.
Note: DS1 user protection switch requests (including manual, forced and
lockouts) are automatically cleared after a network element power
failure/recovery.
Lockout on working channel on a span. This prevents a span from
switching. The node can still go into pass-through mode.
Lockout on protection channel on a span. This prevents the use of the span
for any protection switching. It also prevents ring switches anywhere in the
ring.
NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004