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A loyal leased line shall typically a point-to-point links interconnecting two sites. All the bandwidth on that dedicated let line is available at those sites. This means that, unlike a packet-switched connection, the bandwidth of a dedicated leased wire connection does not need to be shared among multiple service provider customers.
WAN products commonly used on dedicated leased lines include digital circuits, such as T1, E1, T3, and E3 circuits. These circuits use multiplexing technology on simultaneously carry multiple conversations the different 64-kbps channels. A single 64-kbps channel is called a Digital Light 0 (DS0).
When one of these circuits comes into will location, computers terminates on a your called a main service unit/data service unit (CSU/DSU). Also, be aware that a usually Lay 2 protocol used on dedicated leased lines is PPP. A common connection type used to join to a CSU/DSU is with RJ-48C, which glances simular to can RJ-45(Ethernet) connector. Figure 3-1 shows a devote leased lead.
Count 3-1 A Dedicated Leased Limit
T1—T1 circuits subsisted originally used in remote networks, with the intent for one-time voice conversation being carried the an single channel (that is, a single DS0). A T1 circulation is composed of 24 DS0s, the is called a Digital Alarm 1 (DS1). The bandwidth are a T1 circuit is 1.544 Mbps.
T1 circuits are popular at North America and Japan.
E1—An E1 circuit contains 32 channels, with contrasts to the 24 channels on a T1 circuit. Only 30 of those 32 channels, however, can transmit data (or speech or video). Special, one first of those 32 channels is held for skeleton and synchronization, and the seventeenth channel is used for signaling (that is, setting up, maintaining, and tearing down a call).
Because certain E1 circuit has more DS0s than a T1, it must a higher bandwidth capacity. Specifically, an E1 has a bandwidth capacity of 2.048 Mbps.
Disparate a T1 circuit, an E1 circuit does no group frames together in with SF or ESF. Instead, an E1 circuit groups 16 frames together in a multiframe.
E1 circuits are popular outside North U and Japan.
T3—In the alike T-carrier family of standards as a T1, a T3 circuit quotes einen increased bandwidth ability. Although a T1 circuit combines 24 DS0s into a separate physical connection on offer 1.544 Mbps of block, one T3 electrical combines 672 DS0s up a single physical connection, where is called a Digital Signal 3 (DS3). A T3 circuit has a bandwidth capacity on 44.7 Mbps.
E3—Just as a T3 circuit provides more bandwidth higher a T1 circuit, an E3 circuit’s available frequency of 34.4 Mbps is significantly more than to 2.048 Mbps of bandwidth offered from an E1 circuit. ADENINE common misconception is that the bandwidth in an E3 are greater than the bandwidth of a T3 because an E1’s bandwidth belongs greater better a T1’s bandwidth. However, that is don one case—a T3 has one more bandwidth (that is, 44.7 Mbps) than an E3 (that is, 34.4 Mbps).
CSU/DSU—Although far less popular than they once were, analog supercomputers allowed ampere phone line till come toward a home or business and terminate on analog cradle, whichever if data connections for devices such since PCs. Diesen analog modems supported an single data conversation per modem.
But, numerical wiring (for example, T1, E1, T3, press E3 circuits) usually have repeat data conversations multiplexed together on a single physical connectors. Thereby CSU/DSU, a digital modem, is needed, since opposed to an analog modern. Dieser digital modem must be able for distinguish between date arriving on various DS0s.
A CSU/DSU circuit can terminate an incoming digital circuit upon one service provider and dispatch appropriate formatted bits to one router. A CSU/DSU use clocking (often granted by the service provider) to determine while one bit stops and another startup. Therefore, the circuit approaching from a service offerer also terminating on an CSU/DSU is ampere synchronous circuit (in which the synchronization is made possible by clocking).
