 channel. References 1. OSI/IEC 10731, http://www.OSI.org/OSI/en/OSIOnline.frontpage 2. http://www.bipm.orglen/scientific/tai/time_server.htm/ 3. "Fundamentals of DS3." Telecommunications Techniques Corporation Whitepa- per Application Note, 1992; found on: http://www.acterna.com/united_states technical_resources/downloads/white_papers/fund_ds3.pdf This page intentionally left blank NETWORK ARCHITECTURE, FACILITIES, AND SERVICES If network architecture can be thought of as analogous to a frame- work, then facilities and services can be thought of as the bits and pieces that give the architecture detailed substance and a useful purpose. In communications networks, as in broadcast networks, there is an input and output-the basic function. Both must be managed and their assets and cost of operation must be accounted for. Both are enabled with interfaces and protocols. Both tend to evolve and adapt to regulatory and technology forces. More import- antly, those that respond favorably to market demand, survive, grow, and prosper. This chapter is not about how to design and build a telecom network. The intent is to provide information about the nature and characteris- tics of networks sufficient to communicate desires and requirements to potential equipment and service providers using Internet and Telecom terms, standards, and symbols. The overall goal is to help the reader understand communications network architecture, facilities, and ser- vices. The secondary objective is to provide a framework with which to Practical IP and Telecom for Broadcast Engineering and Operations Copyright © 2004 by Fred Huffman. All rights of reproduction in any form reserved. PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS evaluate potential service provider's ability to deliver facilities and services capable of meeting their requirements, and ultimately assess- ing and measuring performance against the terms in a contract. LANGUAGE AND TERMINOLOGY OF COMMUNICATIONS NETWORKS Communications network architecture is most o