Connect Tech Echo/ISA Betriebsanweisung PDF herunterladen (Seite 42)

42 MultiModem ZPX User Guide

private orgovernment-controlled,that provides

telecommunications services. RPOAs, such as AT&T, participate

as non-voting members in the CCITT.

Red Alarm: A T1 error condition generated when a local failure

(e.g., loss of synchronization) exists for 2.5 seconds, causing a

Carrier Group Alarm (CGA). See also “Blue Alarm” and “Yellow

Alarm”.

Request for Comment (RFC): A set of papers in which Internet

standards (published and proposed), along with generally-

accepted ideas, proposals, research results, etc. are published.

RJ-11: An industry standard interface used for connecting a

telephone to a modular wall outlet; comes in 4-and 6-wire

packages.

RJ-45: An 8-wire modular connector for voice and data circuits.

Root Hub: A Universal Serial Bus hub directly attached to the

host controller. This hub is attached to the host; tier 0.

Root Port: The upstream port on a hub.

Router: A device that connectstwo networks using the same

networking protocol. It operates at the Network Layer (Layer 3)

of the OSI model for forwarding decisions.

Routing Information Protocol (RIP): A distance vector-based

protocol that provides a measure of distance, or hops, from a

transmitting workstation to a receiving workstation.

RS-232C: An EIA standard for a serial interface between

computers and peripheral devices (modem, mouse, etc.). It uses

a 25-pin DB-25, or a 9-pin DB-9 connector. The RS-232 standard

defines the purposes, electrical characteristics and timing of the

signals for each of the 25 lines.

RS-422: The EIA standard for a balanced interface with no

accompanying physical connector. RS-422 products can use screw

terminals, DB9, various DB25, and DB37 connectors.

RS-530: The EIA standard for the mechanical/electrical interface

between DCEs and DTEs transmitting synchronous or

asynchronous serial binary data. RS-530 provides for high data

rates with the same connector used for RS-232; however, it is

incompatible with RS-232.

Serial Port: The connector on a PC used to attach serial devices

(those that need to receive data one bit after another), such as a

mouse, a printer or a modem. This consists of a 9- or 25-pin

connector that sends data in sequence (bit by bit). Serial ports

are referred to as “COMx” ports, where x is 1 to 4 (i.e., COM1

through COM4). A serial port contains a conversion chip called a

“UART” which translates between internal parallel and external

serial formats.

Service: The requirements offered by an RPOA to its customers

to satisfy specific telecommunications needs.

Severely Errored Seconds (SES): Refers to a typical T1 error event

where an error burst occurs (a short term, high bit-error rate that

is self-clearing). Per the ITU-T (CCITT) G.821: any second in which

the BER is less than 1x10 -3 .

Signaling: The process of establishing, maintaining, accounting

for, and terminating a connection between two endpoints (e.g.,

the user premises and the telco CO). Central office signals to the

user premises can include ringing, dial tone, speech signals, etc.

Signals from the user’s telephone can include off-hook, dialing,

speech to far-end party, and on-hook signals. In-band signaling

techniques includepulse andtonedialing. Withcommonchannel

signaling, information is carried out-of-band.

Simple Network Management Protocol (SNMP): TCP/IP protocol

that allows network management.

Simultaneous Voice Data (SVD): A technology for letting a user

send data via a modem, and use a handset to talk to another

user at the same time over the same connection. The alternative,

making a second call, can be expensive or even impossible. The

uses for SVD are telecommuting, videoconferencing, distant

learning, tech support, etc.

Stop Bit: One of the variables used for timing in asynchronous

data transmission. Depending on the devices, each character

may be trailed by 1, 1.5, or 2 stop bits.

Switched Virtual Circuit (SVC): A data transmission type where

the connection is maintained only until the call is cleared.

Switched Line: In communications, a physical channel

established by dynamically connecting one or more discrete

segments. This connection lasts for the duration of the call, after

which each segment can be used as part of a different channel.

Contrast with leased line.

Switched Network: A network in which a temporary connection

is established from one point via one or amore segments.

Synchronous Data Link Control (SDLC): A discipline conforming

to subsets of the Advanced Data Communications Control

Procedures (ADCCP) of the American National Standards Institute

(ANSI) and High-level Data Link Control (HDLC) of the

International Organization for Standardization, for managing

synchronous, code-transparent, serial-by-bit information transfer

over a link connection. Transmission exchanges may be duplex,

or half-duplex over switched or nonswitched links. The

configuration of the link connection may be point-to-point,

multipoint, or loop.

Synchronous Transmission: The transmission of data which

involves sending a group of characters in a packet. This is a

common method of transmission between computers on a

network or between modems. One or more synchronous

characters are transmitted to confirm clocking before each

packet of data is transmitted. Compare to Asynchronous

Transmission.

Systems Network Architecture (SNA): The description of the

logical structure, formats, protocols, and operational sequences

for transmitting information units through, and controlling the

configuration and operation of, networks.

TCP/IP: A set of communication protocols that support peer-to-

peer connectivity functions for both local and wide area

networks.

T Carrier: The generic name for a digitally multiplexed carrier

system. In the North American digital hierarchy, a T is used to

designate a DS (digital signal) level hierarchy. Examples: T1 (DS1)

is a 1.544 M bps 24-channel designation. In Europe, T1 is called

E1. The T Carrier system was originally designed for transmitting

digitized voice signals, but has since been adapted for digital data

applications.

T1: A digital transmission link capable of 1.544M bps. T1 uses

two pairs of normal UTP, and can handle 24 voice conversations,

each digitized at 64 Kbps. T1 is a standard for digital transmission

in the U.S., Canada, Japan and Hong Kong. T1 is the access

method for high-speed services such as ATM, frame relay, and

SMDS. See also T Carrier, T1 line and FT1.

Glossary

1 2 ... 37 38 39 40 41 42 43 44 45 46

Kommentare zu diesen Handbüchern

Keine Kommentare

Connect Tech Echo/ISA Betriebsanweisung Seite 42

Kommentare zu diesen Handbüchern