TECHNICAL REFERENCE 10

This chapter provides technical information about how your modem transmits data between users on your LAN and a service provider over the WAN.

TRANSMISSION ON THE WIDE AREA NETWORK

ATM over DMT ADSL is the technology that provides the high-speed transmission between the modem and the service provider. This transmission occurs over a single-pair telephone line. The following sections describe these technologies.

ADSL

Asymmetric Digital Subscriber Line (ADSL) is the technology used to transmit data between the modem and service provider at the physical layer. It provides data at asymmetric rates so that downstream traffic from a service provider to you is faster than upstream traffic from you to the service provider. The downstream transmission rate is up to 7.552 Mbps, while the upstream rate is up to 928 Kbps. Included in the ADSL bandwidth is analog POTS.

Discrete Multitone (DMT) is the line coding used for ADSL. Basically, it divides the bandwidth into subchannels. Some of the subchannels are reserved for analog POTS. The other subchannels are allocated to upstream and downstream traffic. Within the upstream and downstream subchannels, some subchannels are used for management and performance functions.

DMT ADSL provides rate-adaptive transmission that allows the service provider to deliver you the best transmission rate determined by distance and line conditions.

Megabit Modem 400F, 500L, 600F, and 700F User Manual

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