References
1. Dr. Heinz Willebrand and Baksheesh S. Ghuman, Free Spare Optics: Enabling
Optical Connectivity in Today??™s Networks (City: Sams Publishing, 2002).
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Chapter 10
TDM: Circuit Bonding
by William Szeto
While Ethernet is the dominant protocol for the enterprise, its deployment by service
providers in TDM-based networks has been limited. One reason for this limited deployment
is that Ethernet fundamentally is a data transport technology and has difficulty
???fitting??? into a TDM-based network.
A service provider??™s legacy TDM network is designed to support voice services in
a robust manner with only a small amount of signal overhead. By conforming to a
TDM-centric hierarchy, low bit-rate signals are multiplexed neatly into timeslots for
efficient transport, grooming, and switching. While in operation, TDM systems continuously
transmit bits at a fixed rate. This regular transmission of bits aids in monitoring
the health of the transmission system and in clock and data recovery circuitry. The
embedded base of telecommunications equipment was developed with TDM payloads
in mind.
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