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Cisco ONS 15454 SDH Reference Manual, R5.0
April 2008
Chapter 11 SDH Topologies and Upgrades
11.2.6 Two-Fiber MS-SPRing to Four-Fiber MS-SPRing Conversion
Figure 11-12 Connecting Fiber to a Four-Node, Four-Fiber MS-SPRing
11.2.6 Two-Fiber MS-SPRing to Four-Fiber MS-SPRing Conversion
Two-fiber STM-16 or STM-64 MS-SPRings can be converted to four-fiber MS-SPRings. To convert the
MS-SPRing, install two STM-16 or STM-64 cards at each two-fiber MS-SPRing node, then log into CTC
and convert each node from two-fiber to four-fiber. The fibers that were divided into working and protect
bandwidths for the two-fiber MS-SPRing are now fully allocated for working MS-SPRing traffic. Refer
to the Cisco ONS 15454 SDH Procedure Guide for MS-SPRing conversion procedures.
11.3 Subnetwork Connection Protection
Subnetwork connection protection (SNCP) rings provide duplicate fiber paths in the network. Working
traffic flows in one direction and protection traffic flows in the opposite direction. If a problem occurs
in the working traffic path, the receiving node switches to the path coming from the opposite direction.
With SNCP ring networks, switching occurs at the end of the path and is triggered by defects or alarms
along the path.
The network can be divided into a number of interconnected subnetworks. Within each subnetwork,
protection is provided at the path level and the automatic protection switching between two paths is
provided at the subnetwork boundaries. The node at the end of the path and the intermediate nodes in
the path select the best traffic signal. The virtual container is not terminated at the intermediate node;
instead, it compares the quality of the signal on the two incoming ports and selects the better signal.
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Node 1
West East
West East
West East
West East
Slot
5
Slot
12
Node 4
Slot
5
Slot
12
Node 2
Slot
5
Slot
12
Node 3
Slot
5
Slot
12
Tx
Rx
Slot
6
Slot
13
Tx
Rx
Slot
6
Slot
13
Tx
Rx
Slot
6
Slot
13
Tx
Rx
Slot
6
Slot
13
Working fibers