Media and Medium

Chapter 10

Learning Objectives

Identify and discuss the various types of transmission media

Explain how to physically protect transmission media adequately

Identify and discuss the various types of storage media

Know how to lessen the risk of catastrophic loss of information

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Learning Objectives

Understand the various ways to encrypt data

Properly maintain or destroy stored data

Transmission Media

Coaxial cable Twisted pair copper cable

Shielded Unshielded

Fiber-optic cable Wireless connections

Coaxial Cable

Hollow outer cylinder surrounds a single inner wire conductor

Coaxial Cable

More expensive than traditional telephone wiring Less prone to interference Typically carries larger amounts of data Easily spliced; allows unauthorized users access

to the network Two types (not interchangeable)

50-ohm 75-ohm

50-Ohm Coaxial Cable

Uses unmodulated signal over a single channel

Two standards 10Base2 (ThinNet) 10Base5 (ThickNet)

50-Ohm Coaxial Cable

Advantages Simple to implement and widely available Low cost alternative that provides relatively

high rates of data transmission Disadvantages

Can only carry data and voice Limited in distance it can transmit signals

10Base2 (ThinNet)

Uses a thin coaxial cable in an Ethernet environment

Capable of covering up to 180 meters Allows daisy chaining Not highly susceptible to noise interference Transmits at 10 Mbps Can support up to 30 nodes per segment

10Base5 (ThickNet)

Primarily used as a backbone in an office LAN environment

Often connects wiring closets Can transmit data at speeds up to 10 Mbps Covers distances up to 500 meters Can accommodate up to 100 nodes per

segment Rigid and difficult to work with

75-ohm Coaxial Cable

For analog signaling and high-speed digital signaling

75-ohm Coaxial Cable

Advantages Allows for data, voice, and video capabilities Can cover greater distances and offers more

bandwidth Disadvantages

Requires hardware to connect via modems More difficult to maintain

Twisted Pair Copper Cable

Individual copper wires are twisted together to prevent cross talk between pairs and to reduce effects of EMI and RFI

Inexpensive alternative to coaxial cable, but cannot support the same distances

Long been used by telephone companies Types

Unshielded twisted pair (UTP) Shielded twisted pair (STP)

Unshielded Twisted Pair (UTP)

Most common medium for both voice and data

Currently supports up to 1 Gbps protocols

Shielded Twisted Pair (STP)

Extra foil shield wrapped between copper pairs provides additional insulation from EMI

Used extensively in LAN wiring

Shielded Twisted Pair (STP)

Twisted Pair Categories

Category 3 (CAT 3) Category 5 (CAT 5) Category 6 (CAT 6)

Twisted Pair CAT 3

For voice and data transmission

Twisted Pair CAT 5

Supports fast Ethernet Utilizes an 8-pin configuration that can be

modified for use as a crossover cable, straight-through cable, or customized cable

Twisted Pair CAT 6

Supports Gigabit Ethernet Offers backwards compatibility Uses an 8-pin configuration

Twisted Pair

Connects to hardware using an RJ-45 connector

Fiber-Optic Cable

Glass core encased in plastic outer covering

Smaller, lighter, more fragile and susceptible to damage than coaxial or twisted pair cable

Carries light

Fiber-Optic Cable

Fiber-Optic Cable

Advantages Capable of transmitting more data much

further than other wiring types Completely immune to effects of EMI Nearly impossible to splice without detection

Disadvantages Expensive Difficult to install and manipulate

Comparison ofWired Transmission Media

Media Advantages Disadvantages

Coaxial cable High bandwidth

Long distances

EMI immunity

Physical dimensions (difficult to work with)

Easily tapped

Twisted pair copper cable

Inexpensive

Widely used

Easy to add nodes

Most sensitive to EMI

Supports short distances

Limited bandwidth capabilities

Easily tapped

Fiber-optic cable

Very high bandwidth

EMI immunity

Long distances

High security

Small size

Difficult to implement

Expensive

Fragile

Unguided Transmission

Uses various technologies (microwave, radio and infrared) to receive and transmit through the air

Vulnerable to security breaches in which unauthorized users intercept data flow

Difficult to secure; unguided connections cannot be physically contained easily

Securing Transmission Media

Common attacks on data flow include interception and interruption of traffic

Use lock and key Install closed circuit security cameras Use equipment that limits or eliminates

signal leaks Use dry methods for fire extinguishing

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Securing Transmission Media

Deploy an uninterruptible power supply Implement a redundant network Utilize a VPN or other encryption

technology when using wireless LANs Map out cabling and deploy fiber optics in

unsecured areas

Storage Media

Provides a way to hold data at rest Hard disk drive

Developed by IBM in 1970s Ubiquitous

Removable storage media Magnetic Optical Solid-state

Magnetic Storage Media

Coated with iron oxide When data is recorded:

Electromagnet inside disk drive rearranges the iron oxide particles into a series of patterns that represent 0s and 1s

When data is retrieved: Reading disk drive uses a magnetic field to read the

pattern Pattern is translated into data that is sent to computer

in binary form

Types of Magnetic Storage Media

Floppy Disk

3.5 inch, high density 1.44 MB capacity Circular magnetic piece of plastic inside a

rigid plastic case

Zip Disk

High-capacity floppy disk developed by Iomega Corporation

100 MB and 250 MB capacity Relatively inexpensive and durable Ideal for transporting larger multimedia

files Can be used for backup

Optical Storage Media

Light and reflection transmit data

Most common: CD Plastic disc covered by

a layer of aluminum and a layer of acrylic

Typically can store 700 MB of data

Commonly used to store multimedia

Compact Disc

Data is recorded by creating very small bumps in the aluminum layer on long tiny tracks

Data is read by a laser beam, detected by an optoelectronic sensor, and the pattern translated into bits and sent to the computer

CD-ROMs

Most common type of CD Material can be written or recorded to the

disc only once Hold prerecorded materials to be used on a

computer (eg, software, graphic images, short video clips, audio)

Compact Disc-Recordable (CD-R)

User records data onto surface of a blank disc Has layer of light-sensitive dye on top of layer of

reflective gold High-powered laser beam burns data on the disc

Changes color of light-sensitive dye by pulsing in patterns

Write once, read many (WORM) type of media Next step: compact disc-rewritable (CD-RW)

Digital Versatile Disc (DVD)

Can store much more data than a CD Tracks are thinner and closer to each other Readable on both sides of the disc

Made out of plastic with a layer of gold, covered by a thin layer of clear polymer

Used to store full-length feature films

Solid-State Storage Media

Uses a microchip upon which data is recorded directly in digital form

Reliable and durable; no moving parts Very small, yet can contain up to 192 MB

of memory “Flash memory”

Used primarily in digital cameras, digital video cameras, digital audio recorders

Solid-State Storage Media

CompactFlash card SmartMedia card Memory Sticks

CompactFlash Card

Stores up to 1 GB High data transfer rate Resistant to extreme weather conditions

SmartMedia Card

Used in digital still cameras, MP3 recorders, newer printing devices

Stores up to 64 MB of data Less expensive than CompactFlash cards High data transfer rate Resistant to extreme weather conditions

Memory Stick

Holds up to 128 MB of data Commonly used with digital still cameras,

digital music players (MP3), digital voice recorders

High data transfer rate Resistance to extreme temperatures High storage capacity

Secure Digital/Multimedia Cards

Commonly used in MP3 players and digital cameras

Developed to help enforce copyright protections for publishers of music and images

Range in size from 4 MB to 128 MB

Avoiding Catastrophic Loss

Make backup copies of sensitive information and store them at a separate, secure location, preferably in a fire safe

Use a type of media that is less likely to be corrupted or damaged (ie, solid-state)

Encryption

Implement a thorough encryption policy to guarantee that sensitive information does not fall into the wrong hands

Educate the entire organization about the importance of safeguarding sensitive data

Storing Media

Have a policy that tracks content and location of each disk

Mark each medium using a standardized naming scheme

Store copies in a secure location

Destruction of Media

Physically destroy the media Erase the data

Chapter Summary

Transmission media Storage media Impact of different forms of transmission

media and storage media on information security