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Chapter 3

Chapter 3. Topology and Cabling . Building a Network. Step 1. Connecting all computers “physically” by using various networking hardware Step 2. Installing networking software in each computer. Network Topology. What is Network Topology? Physical topology Logical topology.

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Chapter 3

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  1. Chapter 3 Topology and Cabling

  2. Building a Network • Step 1. Connecting all computers “physically” by using various networking hardware • Step 2. Installing networking software in each computer

  3. Network Topology • What is Network Topology? • Physical topology • Logical topology

  4. Physical Topology versus Logical Topology • Physical topology • The way that the computers are physically connected to one another • Logical topology • The way that the signals travel over the network from one computer to the next without regard to the physical interconnection of the computers

  5. Network Topology • What are the four basic Network Topologies? • Bustopology(physical and logical topology) • Ringtopology(physical and logical topology) • Startopology(physical topology) • Meshtopology(physical topology)

  6. Bus Topology • What is the Bus Topology? • All computers are connected to a main line (BUS CABLE (BUS) (physical bus topology)

  7. Bus Topology • What are the characteristics of the Bus Topology? • When a computer transmits data, the signal travels down the BUS in both directions and reaches all of the other computers (logical bus topology) • At the two open ends of a bus, there are terminators to kill/destroy/absorb the signal. • The main disadvantage of the Bus Topology: • A single faulty terminator or a break in the BUS causes the signal to bounce back into the network, and therefore, creates a continuously busy network

  8. Bus Topology

  9. Ring Topology • What is Ring Topology? • All computers are attached to one another to form a closed loop (a ring) (physical ring topology) • Information is passed from one computer to another in either clock-wise direction or counter clock-wise direction (logical ring topology) and after receiving the information, the receiver must send the “acknowledgement” message (ACK message) back to the sender to complete the transmission. As a result, when one computer or ring cable fails, the whole network fails. • ACTIVE TOPOLOGY • EACH computer actively participates in information delivery (actively passing information to another computer) • Every computer in a ring network is a repeater to regenerate the signal that has been attenuated/weakened

  10. Ring Topology

  11. Ring Topology • What are the characteristics of the Ring Topology? • The main disadvantage: • Break in one of the computers or the RING CABLE fails the entire network

  12. Star Topology • What is Star Topology? • All computers are connected to a central wiring point/device (i.e., hub) • Only physical topology (NOlogical star topology) • The signal in a star topology will travel based on BUS or RING logical topology

  13. Star Topology • What are the characteristics of the Star Topology? • Every computer has its own dedicated connection to the hub. Hence, if a single cable fails, only the computer connected to the hub by that cable is affected – better fault tolerance than bus and ring • The main disadvantage: • A faulty hub fails the entire network

  14. Star Topology

  15. Mesh Topology • What is Mesh Topology? • Pure mesh topology: • Each computer has a direct, dedicated line to every other computer in the network

  16. Mesh Topology

  17. Mesh Topology (Fully Connected Topology) • What are the characteristics of the Mesh Topology? • Advantage: • Resilience • Disadvantage: • Difficult and expensive to build in WIRE/CABLE network. More common in WIRELESS network

  18. Network Technology • What is Network Technology (Standard)? • The actualPHYSICAL and DATA LINK layer technology standard that provides a method for a computer to share resource(s) with other computer(s)

  19. Examples of Network Technology • Ethernet • A family of network technologies to build LAN • 10 Base 5 (Thicknet) • 10 Base 2 (Thinnet) • 10 Base T • 100 Base T • 100 Base F • 1000 Base T • 1000 Base F • Token Ring (out of date) • A family of network technologies to build LAN

  20. Network Technology & networking hardware • Network technology defines all of the networking hardware that must be used • If using 10 Base 5 Ethernet, then you will have to use 10 Base 5 NIC, thicknet coaxial cable, ... • If using 100 Base T, then you will have to use 100 Base T NIC, UTP cable, ... • If using 100 Base F, then you will have to use 100 Base F NIC, fiber optic cable, ...

  21. Communication Media: Wire/Cable Media • Coaxial Cable • RG-8 • RG-58 • Twisted Pair Cable • STP • UTP • Fiber Optic Cable

  22. Coaxial Cable • Designed to protect data transmission from electromagnetic interference (EMI) • The signal travels in the center wire • Two examples of coaxial cable: • RG-8, RG-58 • Use in the “Old” Ethernet technology (10Base5, 10Base2)

  23. RG-8 • Thick Ethernet (Thicknet, 10Base5) cable • Transmission Rate - 10 Mbps • Maximum Length (without Repeaters) - 500 meters/segment • Uses transceivers and AUI (Attachment Unit Interface) cable • 2.5 meter between two consecutive connections • Up to 100 nodes per segment/segment

  24. RG-8

  25. Transceiver

  26. RG-58 • Thin Ethernet (Thinnet, 10Base2) cable • Transmission Rate - 10 Mbps • Maximum Length (without Repeaters) - 185 meters • BNC (“Bayonet-Neill-Concelman”) connections • Minimum 0.5 meter between two consecutive connections • Maximum 30 nodes per segment

  27. RG-58

  28. Twisted Pair • STP • The shielding protects data transmission from electromagnetic interference (EMI) • It is used in the Token Ring technology • UTP • No shielding • Most popular cable (because it is the cheapest and good enough for most environments) • CAT rating (CAT1, CAT2, CAT3, CAT4, CAT5, CAT5e, CAT6): • Rated in MHz • Indicating the highest frequency (data transmission rate/speed) the cable can handle • It comes in different numbers of pair (e.g., 2 pairs, 4 pairs)

  29. Fiber Optic Cable • It transmits light • The three basic parts: • Fiber where the light travels • Cladding that makes the light reflects down the fiber • Insulating jacket • Two types of lights: • Light generated by LED • Laser light • High bandwidth (high data transmission rate/speed)

  30. Fiber Optic Cable • Multimode Fiber Optic Cable: • LED light • Slower • Shorter distance data transmission • Larger diameter • Singlemode Fiber Optic Cable: • Laser light • Faster • Longer distance data transmission • Smaller diameter

  31. Fiber Optic Cable • Advantages: • No EMI • Faster • Longer distance data transmission (5000 meters versus 100 meters for UTP) • Smaller size (smaller diameter) • More secure (difficult to tap) • Disadvantages: • Expensive • Difficult to install • Fragile • Fiber Optic cable animation: • http://www.datacottage.com/nch/fibre.htm

  32. Fiber Optic Cable • Fiber optic in YouTube: • http://www.youtube.com/watch?v=v1JEuzBkOD8&feature=related • http://www.youtube.com/watch?v=sOif2kjyiCE&feature=related • Why fiber optic? Why not satellite? (Reliability, capacity, speed, cost) • http://www.betelco.com/bd/bdstel/icee.pdf

  33. Thicknet, Thinnet, UTP, STP, Fiber Optic

  34. Fire Ratings • To reduce the risk of network cables burning and creating toxic fumes and smokes • PVC • Riser • Plenum • Less smoke • Less toxic fume

  35. Networking Industry Standards • What is IEEE? • Non-profit organization • Electrical, computer engineers • To develop and promote the use of electronic and computer technology standards • In the context of IEEE, what is 802? • An IEEE committee whose major responsibility is to develop and promote the use of network technology standards • What are IEEE 802.3, 802.11? • 802.3: a sub-committee of IEEE 802 whose major responsibility is to develop and promote the use of the Ethernet network technology standards • 802.11: a sub-committee of IEEE 802 whose major responsibility is to develop and promote the use of the wireless network technology standards

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