.SAN design reference guide Vol. 1-5 785350-001

WDM system architectures
The WDM system architectures are as follows:
• Passive (optical transmission protocol)
• Active signal amplification
• Active protocol handling
Most WDM products use one of these architectures or combine attributes of each.
Table 132 (page 262) summarizes the WDM system architectures.
Table 132 WDM system architectures
Description
System architecture
1
Passive (optical transmission protocol)
• Transparent to transmission protocol and data-rate independent
• Establishes open interfaces that provide flexibility to use Fibre Channel, SONET/SDH,
ATM, Frame Relay, and other protocols over the same fiber
• Passes the optical signal without any form of signal conditioning such as amplification
or attenuation
Active signal amplification
• Includes line amplifiers and attenuators that connect to other devices through fiber
optic links
• Boosts the signals that are transmitted to and received from peripheral network devices
• Using hardware and/or software control loops, monitors power levels to ensure that
the operation does not exceed the hardware's power budgets
Active protocol handling
• Offers protocol-specific capabilities for Fibre Channel, enabling digital TDM and
optical multiplexing to support multiple channels on each wavelength
• Provides network monitoring, digital retiming (to reduce timing jitter), link integrity
monitoring, and distance buffering
• May require additional and potentially costly transmission hardware when deployed
in meshed networks
Note: HP Continuous Access products using HP FC Data Replication Protocol require
in-order delivery of data replication Fibre Channel frames. Architectures, products, or
protocols that do not guarantee in-order delivery are not supported.
1
Active protocol handling and passive protocol handling require different switch port settings. See “Port protocol setting based on
the extension architecture” (page 265).
WDM system characteristics
To help carriers realize the full potential of WDM, HP-supported WDM systems have the following
characteristics:
• Use the full capacity of the existing dark fiber
• Offer component reliability, 24x7 availability, and expandability
• Provide optical signal amplification and attenuation to increase the transmitted/received
signal-to-noise ratio
• Provide signal conditioning (that is, the retiming and reshaping of the optical data-carrying
signal) for optimization of the bit error rate
• Offer channel add/drop capability (the ability to change the number of data channels by
adding or dropping optical wavelengths on any network node)
• Allow compensation of power levels to facilitate adding or dropping channels
• Provide upgradable channel capacity and/or bit rate
262 SAN extension