Subnetwork Connection Protection Rings; Figure 8-6 Connecting Fiber To A Four-Node, Two-Fiber Ms-Spring - Cisco ONS 15600 Reference Manual

Chapter 8 SDH Topologies and Upgrades
Figure 8-6
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8.4 Subnetwork Connection Protection Rings

SNCP rings provide duplicate fiber paths around the ring. 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.
CTC automates ring configuration. SNCP traffic is defined within the ONS 15600 SDH on a
circuit-by-circuit basis. If a path-protected circuit is not defined within a 1+1 or MS-SPRing line
protection scheme and path protection is available and specified, CTC uses SNCP as the default. You
can set up a maximum of 64 STM-1/4/16 SNCPs or 16 STM-64 SNCPs for each ONS 15600 SDH node.
An SNCP circuit requires two data communications channel (DCC)-provisioned optical spans per node.
SNCP circuits can be created across these spans until their bandwidth is consumed.
Note If an SNCP circuit is created manually by Transaction Language One (TL1), DCCs are not needed;
therefore, SNCP circuits are limited by the cross-connection bandwidth or the span bandwidth, but not
by the number of DCCs.
The span bandwidth consumed by an SNCP circuit is two times the circuit bandwidth, since the circuit
is duplicated. The cross-connection bandwidth consumed by an SNCP circuit is three times the circuit
bandwidth at the source and destination nodes only. The cross-connection bandwidth consumed by an
intermediate node has a factor of one.
Figure 8-7
travels on the working traffic path through Node 1. The same signal is also sent on the protect traffic path
through Node 3.
78-18400-01
Connecting Fiber to a Four-Node, Two-Fiber MS-SPRing
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Node 4
shows a basic SNCP configuration. If Node 0 sends a signal to Node 2, the working signal
8.4 Subnetwork Connection Protection Rings
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Node 2
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Cisco ONS 15600 SDH Reference Manual, Release 9.0
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