Nortel Networks OPTera Metro 3500 - Manual (Page 156)

2-118 Operation, administration, and maintenance (OAM) features
OPTera Metro 3500 Multiservice Platform NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004
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:
• 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.
The Wait to Restore time and Signal Degrade Threshold are provisionable for
OC-48 and OC-192 optical interface pairs and DS1 circuit packs.
Note: DS1 user protection switch requests (including manual, forced and
lockouts) are automatically cleared after a network element power
failure/recovery.
On BLSR rings, user-initiated switches are supported as follows:
• 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.