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1.6 Troubleshooting DWDM Circuit Paths With ITU-T G.709 Monitoring
The entire circuit path has now passed its comprehensive series of loopback tests. This circuit qualifies
to carry live traffic.
1.6 Troubleshooting DWDM Circuit Paths With ITU-T G.709
Monitoring
This section provides an overview of the optical transport network (OTN) specified in ITU-T G.709
Network Node Interface for the Optical Transport Network, and provides troubleshooting procedures for
DWDM circuit paths in the ITU-T G.709 OTN using performance monitoring and threshold crossing
alerts (TCAs).
1.6.1 ITU-T G.709 Monitoring in Optical Transport Networks
ITU-T Recommendation G.709 is part of a suite of recommendations covering the full functionality of
an OTN. ITU-T G.709 takes single-wavelength SDH technology a step further by enabling transparent
optical wavelength-based networks. It adds extra overhead to existing SDH, Ethernet, or asynchronous
transfer mode (ATM) bit streams for performance management and improvement.
ITU-T G.709 adds the operations, administration, maintenance, and provisioning (OAM&P)
functionality of SONET/SDH to DWDM optical networks.
Like traditional SDH networks, ITU-T G.709 optical networks have a layered design
structure enables localized monitoring that helps you isolate and troubleshoot network problems.
Figure 1-40
1.6.2 Optical Channel Layer
The optical channel (OCh) layer is the outermost part of the OTN and spans from client to client. The
optical channel is built as follows:
1.
Cisco ONS 15454 SDH Troubleshooting Guide, R5.0
1-96
Optical Transport Network Layers
OCh
OMS
OTS
OTS
A client signal such as SDH, Gigabit Ethernet, IP, ATM, fiber channel, or enterprise system
connection (ESCON) is mapped to a client payload area and combined with an overhead to create
the optical channel payload unit (OPUk).
OCh Layer
OMS Layer
OTS
OTS Layer
Chapter 1
General Troubleshooting
(Figure
1-40). This
July 2005
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