This chapter contains sections titled: Introduction ITU-T Nominal Center Frequencies Channel Capacity, Width, and Spacing Channel Bit Rate and Modulation Wavelength Management Multichannel Frequency Stabilization Channel Performance Channel Dispersion Power Launched Optical Amplification Fiber Type as the Transmission Medium Optical Power Budget Types of Service Supported Aggregate Bandwidth Management Protocol Used to Transport Supported Services Protocol for Network Management Network Reliability Network and Service Protection and Survivability Strategies Network Scalability and Flexibility Wavelength Management Interoperability and Interdomain Compatibility Single-Mode Power Loss Calculations: An Example Channel Calculations in a Network: Three Examples