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Cisco ONS 15310-MA SDH Reference Manual, Release 9.1 and Release 9.2
78-19417-01
Chapter 9 SDH Topologies and Upgrades
Overlay Ring Circuits
Figure 9-11 Overlay Ring Circuit
Overlay ring supports circuit sizes; VC-3, VC4, VC4-2c, VC4-3c, VC4-4c, VC4-8c, VC4-12c, VC4-16c,
and VC4-64c. Both unidirectional and bidirectional circuits are supported. Overlay ring circuits are
contiguous concatenated (CCAT) and not virtual concatenated (VCAT) circuits.
Manual routing is mandatory while provisioning the overlay ring circuit. Overlay ring circuits created
using Transaction Language 1 (TL1) are discovered by CTC and the status “DISCOVERED” is
displayed.
If the overlay ring circuit is deleted, the cross-connects on the core ring and subtended rings get deleted.
Cross-connects on a subtended ring can be deleted through TL1 but would reflect as a partial overlay
ring circuit in CTC, i.e. core ring will continue having cross-connects.
Subtended
Ring
STM4
Path Protection
Subtended
Rings
Core
Ring
271891
DS3 PASS-THRU
DS3 DROP
DS3 CIRCUIT
STM1 OVERLAY RING
DS3 PASS-THRU
DS3 DROP
Node C
Node A Node B Node D
Node G
Node F
Node E
STM1
Path
Protection
STM1
Path
Protection
STM1
Path
Protection
