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 continued…

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

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 of Wired Transmission Media MediaAdvantagesDisadvantages Coaxial cableHigh 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 continued…

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