Paradyne COMSPHERE 3550 Series User Manual

Also see for Comsphere 3551: Installation manual Quick reference guide

Contents

COMSPHERE 3550 Series Data Service UnitsGlossary-2 July 1999 3550-A2-GB20-40CCITT Consultative Committee on International Telegraphy and Telephony. An advisorycommittee established by the United Nations to recommend communicationsstandards and policies. It was renamed ITU in March 1993.clamping A function of the DSU that forces the output signal to go low (Off) and causes theDSU to ignore input signals.CMI Control Mode Idle. A control signal sent over the DDS line to indicate that no dataactivity is being sent.collision A collision occurs when two tributary DSUs transmit data onto the network at thesame time. The transmissions interfere with each other and neither is successfullyreceived.control A DSU or modem that is, for diagnostic purposes, at the logical head of ahierarchical network. It is the unit from which tests and commands are issued toother units on the same circuit. There is only one control per link.Control Channel(CC)The diagnostic interface between the 6700 Series NMS and the SDU for aModel 3551 DSU, and the Hubbing Device for the Model 3550.core A function of the circuit card that provides data transmission capability. WithModel 3550 or Model 3551 DSUs, there are two cores – one for the DSU and onefor the DBM, and the data can be transmitted through either (also see active core).CSA Canadian Standards Association.CTS The state of the Clear-to-Send lead.Data CommunicationsEquipment(DCE)A device, such as a DSU or modem, that provides an interface between a DTEdevice and a digital or dial/analog network (also called data circuit-terminatingequipment).data router A sophisticated circuit switch in the DSU that is capable of connecting severalcommunication interfaces in more than one way, redirecting or routing data to analternate path.Data Service Unit(DSU)A DCE device that interprets, interfaces, and provides timing and signal controlbetween a DTE device and a digital network.Data Terminal Equipment(DTE) A computer or peripheral device, such as a terminal or printer; a data source or sink.DBM The V.32 dial backup module that can be ordered for the DSU. This moduleoperates at 14.4 kbps and provides an alternate data path in case of failure of thedigital connection through the dial network.DDS Digital Data Service, such as the ACCUNET Spectrum of Digital Services thatprovides digital (not dial) communication circuits.dedicated backup A dial backup module (DBM) assigned to a particular DSU that is continuallyavailable for service restoration. The DBM switches to Dial Backup modeautomatically when the DDS line fails; no switching is required. An external dialbackup unit (DBU) can also provide dedicated backup.