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Chapter 7
Chapter 7
| WAN Technology | Typical Available Bandwidth |
|---|---|
| Frame Relay | 56 kbps–1.544 Mbps |
| T1 | 1.544 Mbps |
| T3 | 44.736 Mbps |
| E1 | 2.048 Mbps |
| E3 | 34.4 Mbps |
| ATM | 155 Mbps–622 Mbps |
| SONET | 51.84 Mbps (OC-1)–159.25 Gbps (OC-3072) |
| Term | Definition |
|---|---|
| Telco | A telco is a telephone company. Some countries have government-maintained telcos, while other countries have multiple competitive telcos. |
| Local loop | A local loop is a connection between a customer premise and their local telephone central office (CO). |
| Central office (CO) | A building containing a telephone company’s telephone switching equipment is referred to a central office (CO). COs are categorized into five hierarchical classes. A Class 1 CO is a long-distance office serving a regional area. A Class 2 CO is a second-level long-distance office (it’s subordinate to a Class 1 office). A Class 3 CO is a third-level long-distance office. A Class 4 CO is a fourth-level long-distance office that provides telephone subscribers access to a live operator. A Class 5 CO is at the bottom of the five-layer hierarchy and physically connects to customer devices in the local area. |
| Tip and ring | The tip and ring wires are the red and green wires found in an RJ-11 wall jack, which carry voice, ringing voltage, and signaling information between an analog device (for example, a phone or a modem) and a telephone’s wall jack. |
| Demarc | A demarc (also known as a demarcation point or a demarc extension) is the point in a telephone network where the maintenance responsibility passes from a telephone company to the subscriber (unless the subscriber has purchased inside wiring maintenance). This demarc is typically located in a box mounted to the outside of a customer’s building (for example, a residential home). This box is called a network interface device (NID). |
| Smart jack | A smart jack is a type of network interface device (see the definition for demarc) that adds circuitry. This circuitry adds such features as converting between framing formats on digital circuit (for example, a T1), supporting remote diagnostics, and regenerating a digital signal. |
