Page 103 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Exposure to Computer Disciplines

Notes
Figure 5.14: STP Cable

5.4 Basic Hardware

All networks are made up of basic hardware building blocks to interconnect network nodes,
such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition,
some method of connecting these building blocks is required, usually in the form of galvanic
cable (most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.12)
or optical cable (“optical fiber”).
5.4.1 Network Interface Cards
A network card, network adapter, or NIC (network interface card) is a piece of computer hardware
designed to allow computers to communicate over a computer network. It provides physical
access to a networking medium and often provides a low-level addressing system through the
use of MAC addresses.
Each network interface card has its unique id. This is written on a chip which is mounted on the
card.

Figure 5.15

Computer
attached to
a network
LAN
connection Network Processor
interface and
hardware memory

Transmits and Generates outgoing
receives frames data and handles
on the LAN incoming data

5.4.2 Repeaters
A repeater is an electronic device that receives a signal, cleans it of unnecessary noise, regenerates
it, and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal
can cover longer distances without degradation. In most twisted pair Ethernet configurations,
repeaters are required for cable that runs longer than 100 meters. A repeater with multiple ports
is known as a hub. Repeaters work on the Physical Layer of the OSI model. Repeaters require a
small amount of time to regenerate the signal. This can cause a propagation delay which can affect
network communication when there are several repeaters in a row. Many network architectures
limit the number of repeaters that can be used in a row (e.g. Ethernet’s 5-4-3 rule).

96 LOVELY PROFESSIONAL UNIVERSITY