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Introduction
Published in P. S. Neelakanta, ATM Telecommunications, 2018
The frame-relay is designed to eliminate much of the overhead that X.25 imposes on the end-user systems and on the packet-switching network. It involves a streamlined packet transmission with certain associated functions. These functions refer to eliminating error-checking and flow-control to realize greater throughput. It supports data rates up to 1.544 Mbps (DS-1 rate) which is much higher than the rate available with X.25 packet networks. A frame-relay transmission consists of a customer-premises network routed into a frame-relay service provider cloud through a local access line. Also, a conversion of unipolar bits into bipolar bits by means of a channel service unit/data service unit (CSU/DSU) (so as to be compatible for local access line) is done.
Modems and Interfaces
Published in Paul W. Ross, The Handbook of Software for Engineers and Scientists, 2018
Digital transmission service is increasingly available from local communications carriers (“the phone company”). In general the installed communications plant in industrial countries is at its core digital, with analog voice service to the customer premises. Using this digital capacity directly, rather than through a modem, provides higher data rates and lower error rates. To do this a different sort of interface box is required; rather than a modem a “channel service unit/data service unit” (CSU/DSU) is needed to establish correct digital signal levels and format between the computer and the phone line. The CSU/DSU provides synchronous data communications and therefore uses an RS-449 interface (or a variation such as RS-422 or V.35).
The Data Center Manager’s Guide to Networked Imaging Systems
Published in Steven F. Blanding, Enterprise Operations Management, 2020
Access to SMDS is provided via dedicated lines. On each access line, the required customer-premises equipment consists of a router with an SMDS interface and a CSU/DSU (channel service unit/data service unit) with an SMDS interface. A DXI provides standardized connectivity between the two devices, while a LMI permits the CSU/DSU to pass performance information to the router so it can be sent to a SNMP-based management workstation.
A Survey on Packet Switching Networks
Published in IETE Journal of Research, 2022
The LAN of an endorser is commonly associated with the SMDS service through a router utilizing an RS-449 interface and a Channel Service Unit/Data Service Unit (CSU/DSU) utilizing a copper DS1 association (1.544 Mbps) for low-speed access or a fiber DS3 association (44.736 Mbps) to accomplish the most noteworthy conceivable transmission speeds.