From High-Performance Data Network Design: Design Techniques and Tools

7.1 Wide area network design principles

7.1.1 Basic concepts and terminology

The telephone network

The terminology used in wide area networking is extensive, and for those of us who were baptized in data networks in the 1980s and 1990s, much of this terminology appears archaic, with its roots firmly planted in telephony. Nevertheless, it is worth revisiting the source of this terminology briefly, since these terms frequently appear in material concerning the migration from circuit-switched to packet-switched networking.

Telephone networks were originally designed as a rigid hierarchy, as illustrated in Figure 7.1, and many of the components of this model have alternate names, as shown, sometimes adding to the confusion. At the core of the network are a handful of regional centers. High-capacity trunks distribute call traffic through progressively smaller switching offices, until we reach the Central Office (CO). Between the larger switching offices, coaxial cable, microwave, and fiber-optic cables are used. Cable distribution is defined by a tree topology; as we near the subscriber, large, multipair copper is spliced and joined to form many smaller bundles (e.g., 900-pair to 3 300-pair to 6 150-pair to 18 50-pair and so on). From the central office, 2-pair unshielded copper cable is delivered to individual subscriber premises over what is termed the local loop.

Figure 7.1: Structure of the telephone network and associated terminology.

Point of Presence (PoP)

A Point of Presence (PoP) is a provider location where DCE equipment is deployed to terminate user access from a variety...

Products & Services
Network Wiring and Cabling Services
Network wiring and network cabling services install copper and fiber optic cable within buildings or central offices.
LAN, MAN, and WAN Network Design Services
LAN network design, MAN network design and WAN network design services design large-scale networks for communication providers or large-enterprise businesses.
Fieldbus Products
Fieldbus products are industrial automation products used in industrial network communications on factory floors.
Network Modems
Network modems (modulators-demodulators) are devices or programs that allow computers to transmit data over telephone lines. They convert digital computer data to analog sound waves and then demodulate the carrier signals to decode the transmitted information.
Network Processors
Network processors handle a wide array of tasks needed to support network systems, including routing, compression, encryption, authentication, and protocol conversion.

Topics of Interest

7.2 Encapsulation techniques Packet- and cell-switched data are moved over wide area circuits by first encapsulating these data. This encapsulation typically embodies addressing and control...

An understanding of the public switched telephone network (PSTN) and how it is potentially going to be replaced is best grasped by understanding its three major components: access, switching, and...

An understanding of the workings of the Public Switched Telephone Network (PSTN) is best grasped by understanding its three major components: access, switching, and transport (see Figure 2-1). Each...

7.1 Introduction Consumer demand for ready access to Web resources, multimedia applications, and information on every topic imaginable undermines the capabilities of the PSTN (Public Switched...

Network Topology Before we enter the central office, we should pause to explain the topology of the typical network (please refer to Figure 3-9). The customer s telephone, and most likely, their PC...