Figure 20–4 Combining RJ-11 and RJ-45 modular jacks in one module.

Figure 20–1 The structure of the metropolitian statistical area is divided into four distinct regions—the core; the regional network; the metropolitan core network; and numerous access networks, which cover the customer premises and building locations.

Figure 20–2 The demarcation point at the customer premises is often located in the basement of the building. The cable from the outside plant is terminated onto some type of block.

Figure 20–3 Multitenant buildings require that the telephone company demarcation point resides in one location, typically in the basement. The outside cable is connected to inside wiring and fed to the appropriate locations. (a) A small customer. (b) A multitenant building. (c) A company using the entire building.

Figure 20–3 (continued) Multitenant buildings require that the telephone company demarcation point resides in one location, typically in the basement. The outside cable is connected to inside wiring and fed to the appropriate locations. (a) A small customer. (b) A multitenant building. (c) A company using the entire building.

Figure 20–4 Combining RJ-11 and RJ-45 modular jacks in one module.

Figure 20–5 Small businesses have fully networked LANs. A typical small business has file servers, workstations, scanners, printers, and multimedia workstations. Shown here is an Ethernet LAN with a router used to access the outside network.

Figure 20–6 The types of termination blocks found in small business locations vary depending on the choice of the network manager. Three types of termination panels are shown, along with a Smart Jack that terminates T1 circuits.

Figure 20–6 (continued) The types of termination blocks found in small business locations vary depending on the choice of the network manager. Three types of termination panels are shown, along with a Smart Jack that terminates T1 circuits.

Figure 20–7 The 66 block is used to connect two pieces of cable at a customer’s premises.

Figure 20–8 The 66 termination block is used as a cross-connect point between outside wire cable, inside wire cable, and terminating equipment such as a Smart Jack, shown in the diagram.

Figure 20–9 Small business owners often place small switches called private branch exchanges (PBXs) at their location to switch all calls within the business. Trunks are established between the PBX and the telephone company’s switch. The trunks are used to switch calls leaving the premises.

Figure 20–10 The RJ-48 jack is used to terminate four-wire circuits such as T1s.

Figure 20–11 A common data room layout. Terminals are connected to hubs. The hubs feed into a router or are fed back to file servers depending on the destination request. The VAX mainframe has an RS-232 interface that feeds into an access terminal that converts RS-232 into Ethernet. The Ethernet interface feeds into the router. The database also requires an RS-232 conversion at the access terminal. The UPS system sitting at the corner is used to provide backup power if commercial power is lost.

Figure 20–12 Typical business location that has multiple T1 lines. A Smart Jack shelf is placed in a relay rack in the telephone room at the business premises. The T1 provides connections to the outside world for both voice and data traffic.

Figure 20–13 A typical business location that has two buildings connected by fiber. Each building has an optical MUX that drops out T1 circuits.

Figure 20–14 Typical residential customer that requires voice and data circuits. Residential communications networks vary dramatically due to different requirements. Voice and data require separate analog lines if the user wishes to use both simultaneously.

Figure 20–15 Dial-up Internet lines interface RASs before being aggregated onto circuits interfacing the switch. RASs replace modem pools. From the switch, the traffic is routed to a router that points the traffic to the Internet.

Figure 20–16 Generic depiction of a data point-to-point system.

Figure 20–17 Data circuits travel across the telephone network and are classed as either two-wire (a) or four-wire circuits (b).

Figure 20–18 The ingress and egress of a network.

Figure 20–19 Core backbone network connected in a mesh configuration. Many carrier class data networks are configured this way.

Figure 20–20 How the backbone network and the access network connect in a region.

Figure 20–21 Routers connect data networks together and route packets to the correct destination.

Figure 20–22 How LAN connections are made between two locations.

Figure 20–23 Frame relay networks require a frame relay device to interconnect to the DTE. The DTE may be a router, a file server, or a front-end processor.

Figure 20–24 Frame relay switches route traffic between points.

Figure 20–25 A DSLAM is located at the serving wire center and feeds subscribers on the normal cable pair. The DSLAM aggregates all of the subscribers’ traffic and sends it on to the regional switch site. At the regional switch site, data are routed onto the backbone network. The data travel across the backbone network to the Internet.

Figure 20–26 Dial-up connection between two PCs. Both telephone lines are served out of the same central office switch.

Figure 20–27 DSL modems connect to the network via RJ-11 jacks similar to analog modems and to the computing device via Ethernet.

Figure 20–28 Typical interfaces used when connecting a CSU to the terminating equipment.

Figure 20–29 A loop-back condition at the CSU. The purpose of a loop back is to help isolate trouble on the line.

Figure 20–30 Shown is a circuit connection that routes from an outside network to a CSU, passes through a multiplexer and an FEP, then terminates into a mainframe computer. The multiplexer also drops off other circuits at the location.

Figure 20–31 A circuit interfacing into a front-end processor. An FEP’s circuit rates vary depending on the amount of information required by the customer.

Figure 20–32 A circuit connection from the outside network to the mainframe. The mainframe is preceded by an FEP that organizes the information before passing it on to the mainframe.

Figure 20–33 The RS-232 cable has both nine-pin male and nine-pin female connectors. RS-232 cables are commonly used to connect computing devices. (Photo courtesy of M. A. Rosengrant)

Figure 20–34 RS-232 connectors are found in either a twenty-five-pin or a nine-pin configuration.

Figure 20–35 The V.35 interface is commonly used for data speeds above 19.2.

Figure 20–36 G.703 standard defines the T1 interface. The T1 circuit is a four-wire circuit.

Figure 20–37 BNC connectors are used to terminate DS-3s, thin and thick Ethernet signals, and higher-rate STSs.

Figure 20–38 Typical fiber optic termination. (a) The side view of a connector; (b) front view; (c) jack the connector fits into.

Figure 20–39 Point-to-point data circuit. The circuit speed may vary depending on the bandwidth needs. The circuit architecture is commonly used by banks in order to keep the network secure.

Figure 20–40 Multipoint data circuit with three remote ATM locations feeding into a front-end processor (FEP). From the front-end processor, the transaction is routed to the mainframe. The mainframe polls each of the sites and asks for information. The remote sites are not able to talk with each other, only to the mainframe at the main office.

Figure 20–41 The bus network topology. The network consists of elements tied together along a shared route. Traffic from each device flows through the adjacent device as it travels down the line.

Figure 20–42 A typical ring architecture. Traffic flows around the ring passing through each node along the route.

Figure 20–43 This partial mesh network provides connectivity between at least two other nodes. Some networks are fully meshed, meaning that each node is connected to every other node in the network.

Figure 20–44 Mesh networks provide redundant paths to each device on the network. For example, if the link between A and B fails, the traffic to C is rerouted through F, then to C.

Figure 20–45 LANs are composed of devices tied to a shared bus, forming one segment. One segment is defined by the same IP address structure.

Figure 20–46 Three-segment Ethernet LAN.

Figure 20–47 LAN connections are made between multiple users’ devices and a hub using twisted copper pair as the connection medium.

Figure 20–4 Combining RJ-11 and RJ-45 modular jacks in one module.