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CHAPTER Communication Media. Chapter Objectives. Present the functions and features of leading transmission media, both guided and open media Guided media Twisted pair, coaxial cable, optical fiber and mixed cabling Open media (space) RF, Ultraviolet, Microwave and satellite.
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Chapter Objectives • Present the functions and features of leading transmission media, both guided and open media • Guided media • Twisted pair, coaxial cable, optical fiber and mixed cabling • Open media (space) • RF, Ultraviolet, Microwave and satellite
Chapter Modules • Twisted Pair • Coaxial Cable • Optical Fiber • Mixed Cabling • Wireless • Microwave • Satellite Communication
MODULE Twisted Pair Wire
Questions • What are the two different types of twisted pair wires that are in use? • Why are the wires twisted? • Name the categories of wires and their respective uses • What is the role played by bandwidth in the quality of the wires? • What is a Plenum wire? Where is it used? • Name the types of twisted pair wires that could be used in high speed LANs such as the Gigabit Ethernet LAN • Describe the properties of the newer categories of twisted pair wires
Terminology to Remember • Shielding (Conductive material) • Insulation (Non-conductive material) • Casing (Plastic material)
Types and Purpose of Twisting • Types • Unshielded twisted pair (UTP) • Shielded twisted pair (STP) • Twisting • Minimizes the effect of electromagnetic interference • The electromagnetic field from one wire counterbalances the field from the other wire
Shielding and Insulation • The cables are shielded from electro magnetic interference • In both directions, from outside as well as inside • The plastic casing is not to be considered as shielding • It is an insulation against electric shock
Twisted Pair Cable Illustration Source: Black Box
Characteristics • Cheap • Easy to install • Generally speaking, different frequencies may not be assigned to carry different channels on the same twisted pair wire • Compared to coaxial cables, twisted pair wires have a lower bandwidth • But, recent improvements have contributed to an increase in bandwidth • Speed is proportional to bandwidth
Quality and Categorization of the Wires • Twisted pair wires are categorized according to their quality • Category 3 wires are of the lower quality • Category 5, 5e, 6 etc. wires are of higher quality • Partly achieved by having a larger number of twists in the cable • Higher category wires such as Cat 6 etc. are now available
Areas of Application • Phone lines • Used extensively in telecommunications • LANs
Typical Twisted Pair Connection Hub/Switch Twisted Pair Wire
Reasons for its Increasing Popularity • Better quality UTP is being produced • Ease of installation superseding its other limitations • A LAN to be configured with twisted pair wires requires a hub • A hub based implementation is preferred because it is easy to install and manage
Gigabit Ethernet Medium • IEEE 802.3ab Twisted Pair • Cat 5e (350 MHz/ 1Gbps) • IEEE 802.3z Fiber Optics
LAN Speed • The following questions apply to the LAN shown in the next slide • What is the speed of the network? • How could it be upgraded to a higher speed?
Important Areas of Application for Twisted Pair Wires • LAN • RJ 45 • 10baseT LANs operating at 10 Mbps • 100baseTX LANs operating at 100 Mbps • 1000baseT LANs operating at 1 Gbps • 8 wires • Telephone wiring connections • RJ 11 (4 wires) • RJ 14 (6 wires)
Questions • What are the two different types of twisted pair wires that are in use? • Why are the wires twisted? • Name the categories of wires and their respective uses • What is the role played by bandwidth in the quality of the wires • What is a Plenum wire? Where is it used? • Name the types of twisted pair wires that could be used in high speed LANs such as the Gigabit Ethernet LAN • Describe the properties of the newer categories of twisted pair wires
MODULE Coaxial Cable
Questions • Name the two types of coaxial cables • Name different use for each type of cable • Are they shielded? • What is the difference between shielding and insulation? • Explain the current replacements for coaxial cables both at the lower and higher end of the coaxial cable
Questions • List the uses for thin and thick coaxial cables • Name the types of LANs that use coaxial cables
A Description of the Coaxial Cable Outer casing Insulator Shielding Copper conductor
Types of Coaxial Cables • Thin coaxial • Lighter version • Thin Ethernet cable • Thick coaxial • Original version • Standard Ethernet cable
Thin Coaxial Cable • Higher bandwidth than twisted pair wires • Lower bandwidth compared with the thick coaxial able • More flexible compared to thick coaxial cable • Cheaper
Type of Thin Coaxial Cable Used in LAN • Standardized • 10Base2 cable • 10M bps • Ethernet • Thin coaxial cable • Bus topology
Thick Coaxial Cable • Compared to thin coaxial cable • Higher bandwidth • Less maneuverable • More expensive
Thick Coaxial Cables Used in Networks • Standardized • 10Base5 • 10M bps • Ethernet • Thick coaxial cable • Bus topology
Overall Characteristics of the Coaxial Cables • Relatively cheap compared to fiber-optic cables • Wider bandwidth compared to twisted pair wires • Good transmission characteristics • Used in high-speed synchronous transmission • Supports broadband communication • Can be tapped for multi-drop connection
A Typical Coaxial Connection Bus LAN Coaxial Cable A multi-drop connection
Components Used in Connecting a Computer to a Coaxial Cable T connector Network Interface Card Thin coaxial cable Terminator
An Example of the Use of Thick Coaxial Cables Switch Coaxial Cable Router Backbone Thick coaxial cable
Areas of Application for Coaxial Cables • Ethernet bus LANs • Telephone trunks • Mainframe networks • Cable TVs
Future of Coaxial Cables • Overall use is on the decline • LANs (Lower End) • Replaced by newer and better twisted pair wires • Telephone trunks (Higher End) • Fiber cables are replacing coaxial cables • Mainframes of yesterday or perhaps today as well • Connected to peripheral devices over larger networks built on fiber-optic cables and twisted pair wires
Questions • Name the two types of coaxial cables • Name different use for each type of cable • Are they shielded? • Are they insulated? • Explain the current replacements for coaxial cables both at the lower and higher end of the coaxial cable • List the uses for thin and thick coaxial cables • Name the types of LANs that use coaxial cables
MODULE Fiber Cables
Questions • How does light travel in a fiber cable? • Name the different types of optical transmission methods • What is the most appealing aspect of fiber cables? • What are their consequences? • What are the two different types of fiber cable connections used in practice? • What are the two different materials that could be used in the production of fiber cables? • Where are fiber cables used mostly in a LAN?
Increasing Speed Fiber Optics Transmission • Light travels along the path of the fiber by bouncing around its edges • Propagation methods • Multi-mode step index • Multi-mode graded index • Single mode
Characteristics • Very broad bandwidth • Higher transmission speeds are possible • Signals travel a longer distance • No Electro-magnetic field • No interference • Signals are difficult to tap • Smaller size • Multiple fiber strands can be included in a cable of very small diameter
Fiber-Optic Cable Bandwidth Part Of Ultraviolet Fiber Optics Visible Part Of Infra-red ? The laser beam could also travel along a fiber optic cable
Usage of Fiber Optic Cables • Long distance telephone cabling (trunks) • LANs • Used in large networks as the backbone • An example is the FDDI backbone used in a number of campuses • Used for extending cable limitations applicable to networking and other computing devices
A Simple Fiber LAN Source: Black Box
Types and Cost • Types • Regular glass fibers • Plastic fibers • Purer the fibers the better the transmission characteristics • Cost • Fiber cables are costlier than twisted pair wires and coaxial cables • The cost has declined over a period of time • Plastic fiber cables are cheaper than glass fiber cables
Fiber Usage • Network backbones • Extending distance between network connections • Connecting high speed switches
Web Research • Visit the following link at Corning for a tutorial on fiber optic technology http://www.corning.com/prod_svcs/index.html • http://www.corningfiber.com/library/lib_premises.htm