CHAPTER
18-1
Cisco ONS 15454 DWDM Installation and Operations Guide, R6.0
August 2005
18
Network Reference
This chapter explains the ONS 15454 dense wavelength division multiplexing (DWDM) network
applications and topologies. The chapter also provides network-level optical performance references.
Note Unless otherwise specified, “ONS 15454” refers to both ANSI and ETSI shelf assemblies.
Chapter topics include:
• 18.1 Network Applications, page 18-1
• 18.2 Network Topologies, page 18-2
• 18.3 Optical Performance, page 18-6
• 18.4 Automatic Power Control, page 18-18
• 18.5 ROADM Power Equalization Monitoring, page 18-22
• 18.6 Span Loss Verification, page 18-23
• 18.7 Network Optical Safety––Automatic Laser Shutdown, page 18-24
• 18.8 Network-Level Gain—Tilt Management of Optical Amplifiers, page 18-28
18.1 Network Applications
Cisco ONS 15454s can be provisioned for metro access and metro core DWDM network applications.
Metro access networks are 60 km or less in size. Channels are not equalized and dispersion compensation
is not applied. Metro access networks have few spans and very low span loss, so the signal link budget
is the limiting factor for performance. Metro core networks can be up to 400 km in size. The channel
power is equalized and dispersion compensation is applied. Metro core networks often include multiple
spans and amplifiers, so the optical signal-to-noise ratio (OSNR) is the limiting factor for channel
performance in metro core networks.
Within DWDM networks, the ONS 15454 uses a communications protocol, called node services protocol
(NSP), to communicate with other nodes. NSP automatically updates nodes whenever a change in the
network occurs. Each ONS 15454 DWDM node can:
• Identify other ONS 15454 DWDM nodes in the network.
• Identify the different types of DWDM networks.
• Identify when the DWDM network is complete and when it is incomplete.
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