Instruction manual

TurboStack Chassis and Backplanes

DEPARTMENT CONCENTRATOR—Hub which provides a large number of

workstation connections. The term, department concentrator, refers to multiple

repeaters housed in a chassis. See Hub, Repeater.

DIX CONNECTOR—See D-Sub Connector.

FOIRL — A ﬁber optic standard that allows up to 1,000 meters (3,280 ft.) of multimode

duplex ﬁber optic cable in a point-to-point link.

HARMONICA ADAPTER—This adapter provides a simple way to convert the 50-pin

Telco connection to RJ45 connections.

HEARTBEAT—See SQE.

HOT SWAPPING— The process of replacing a hub module without bringing down the

network. This process occurs by sliding an active module into a fully powered up

concentrator, replacing a failed module.

HOUSE WIRING—House wiring is the existing wiring inside a building. This wiring

generally originates from one or more wiring closets such as a telephone room. Some

older buildings may have wiring unsuitable for 10 megabit data rates. In these

circumstances, it is recommended that the wiring is tested with a 10BASE-T signal/wire

tester.

HUB—A hub is a central signal distributor. It is used in a wiring topology consisting of

several point-to-point segments originating from a central point. The term hub is often

used interchangeably with the term repeater. Multiport 10BASE-T, 10BASE2 and ﬁber

optic (10BASE-FL, FOIRL) repeaters are considered hubs. See Repeater.

HUB-to-HUB WIRING—See MAU-to-MAU Wiring.

HUB-to-MAU WIRING—UTP cables for 10BASE-T hub-to-MAU or NIC cards are

wired straight-through. An RJ45 receptacle at the hub would wire pin-to-pin to the

RJ45 receptacle at the MAU.

IMPEDANCE—An electrical characteristic of a circuit dealing with the combination of

the AC and DC resistance and the appearance of that resistance to attached circuits.

JABBER LOCK-UP—The MAU’s ability to automatically inhibit the transmit data

from reaching the medium if the transmit data time exceeds a speciﬁed duration. This

duration is in the range of 20 ms to 150 ms. Jabber lock-up protects the medium from

being overrun with data packets from a possibly defective device.

JAM—This is a term used to describe the collision reinforcement signal output by the

repeater to all ports. The jam signal consists of 96 bits of alternating 1s and 0s. The

purpose is to extend a collision sufﬁciently so that all devices cease transmitting.

JITTER—The ﬂuctuation of the data packet in respect to a standard clock cycle. Jitter

is undesirable and must be minimized.

LINK SEGMENT—The link segment of coaxial cable is a segment which has no MAU

devices but links two LAN devices together such as repeaters.