Marconi OMS 1200
Technical Product Description
221 02-ZAP 701 25/1 Rev C 2006-08-04
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7.6
1+1 Tandem VC-Trail SNC Protection (TSNCP)
7.6.1
Introduction to TSNCP
Full-TCM monitoring functions add VC-path, client layer, fault types to the list of
criteria for setting the internal SF/SD flags of SNC protection schemes, which initiate
autonomous protection switching actions. When TCM fault types are included in the
protection switching criteria, the operator configured protection scheme is referred to
as Tandem Subnetwork Connection Protection (TSNCP).
A tandem connection is a segment of a VC-trail, a SNC, which typically spans across
only a single network operator domain, and on which TCM functions have been
configured.
If you have not configured TCM on your VC-trail segment, this segment is another
normal SNC, and can be protected by 1+1 SNCP.
If you have configured TCM on the VC-trail segment, it is classed as a tandem SNC,
and can be protected by 1+1 TSNCP.
TCM functions allow you to monitor the performance of a VC-path across the specific
segment, which lies within your administrative domain. This is known as sub-layer
monitoring. It does not affect the ability for normal end-to-end VC-path monitoring
across the whole network(s).
7.6.2
Modes of Operation for TSNCP
The operator configurable modes of operation, including TSNCP persistency, are as
described in Section 7.5.2 above, for VC-trail SNCP.
Similar to SNCP, if TSNCP is applied across the complete end-to-end tandem VC-trail
then the two SMAs involved can operate in bi-directional switching mode.
Note:
This is only true when the SMAs are handling bidirectional traffic signals on
normal bidirectional VC-trail TSNCs.
The default mode is bi-directional and this should always be selected if the following
conditions are met:
•
The two SMAs are commissioned as full-TCM NE types
•
The two SMAs are configured for TCM processing
•
Tandem Connection Termination functions (TCTs), and not monitor functions
(TCMs), are configured on the worker/protection bearer SDH interface units
at each SMA, i.e. the node being configured is actually terminating a tandem
VC-trail and not just monitoring at an intermediate node along the trail).