1. CIM 2465 Network Connectivity1 Network Connectivity (Topic 2) Textbook: Networking Basics, CCNA 1 Companion Guide, Cisco Press Cisco Networking Academy Program, CCNA 1 and 2, Companion Guide, Cisco Press, Latest Edition

2. CIM 2465 Network Connectivity2 Analog Signal Vs Digital Signal Analog data is continuous data The world we live in is mainly an analog world. E.g. light, video, voice Digital data is discrete, values are distinct from one another. Digital computers process data in digital form (0 or 1) A/D D/A conversion (e.g. modem)

3. CIM 2465 Network Connectivity3 Analog Signal Vs Digital Signal

4. CIM 2465 Network Connectivity4 Properties of an Analog Signal Amplitude Frequency Phase Modulation and Demondulation

5. CIM 2465 Network Connectivity5 Factors Affecting Transmission of Signals Noise –Refers to any interference on the physical medium that makes it difficult for the receiver to detect the data signal –Crosstalk Noise created on one wire as a result of current flowing over a nearby wire Attenuation –Attenuation in an electrical signal is a decrease in voltage as the signal crosses the wire –Can be caused by Resistance of wires Energy loss Frequency of signal

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7. 7 Digital Transmission Digital Transmission is a general term that refers to how computing devices transmit the binary bits from one to another Can be done by (Modulation) –Varying (modulating) an electrical signal as it passes over a copper wire –Varying the power of light as sent over an optical fiber –Varying the radio waves sent through space, wireless communications

8. CIM 2465 Network Connectivity8 Transmission Media Major types –Copper Wires Coaxial Cable, Shielded Twisted Pair (STP), Unshielded Twisted Pair (UTP) –Optical –Wireless Considerations –Transmission speed –Digital or Analog transmission –Transmission distance

9. CIM 2465 Network Connectivity9 Coaxial Cable Composed of a single copper wire, surrounded by an insulating shell, then a second conductor shield, and a plastic outer shell –Types: Thick Coaxial (10Base5) Thin Coaxial (10Base2) Today’s modern LANs no longer use 10BASE5 and 10BASE2

10. CIM 2465 Network Connectivity10 Coaxial Cable Advantages –Longer transmission distance than STP and UTP, fewer repeaters needed –Less expensive than fiber-optic, more expensive than STP and UTP –High bandwidth medium that can carry thousands of signals, support broadband transmission of cable TV, a single cable is divided into many channels for transmission. Commonly used to deliver cable- television signals and high-speed Internet access

11. CIM 2465 Network Connectivity11 Coaxial Cable

12. CIM 2465 Network Connectivity12 Twisted Pair Wire Most commonly used data transmission medium Its core consists of pairs of copper wires twisted together to create magnetic field and thus reduce interference 2 types: –Shielded Twisted Pair (STP) –Unshielded Twisted Pair (UTP)

13. CIM 2465 Network Connectivity13 Shielded Twisted Pair (STP)

14. CIM 2465 Network Connectivity14 Shielded Twisted Pair (STP) Shielding provides a cleaner electrical current by reducing attenuation and noise, thus longer cabling lengths More expensive, heavier, and difficult to bend when installing them (compare with UTP)

15. CIM 2465 Network Connectivity15 Unshielded Twisted Pair (UTP) Grouped into categories based on quality Generally used in LAN Cat 5 cable RJ45 connector

16. CIM 2465 Network Connectivity16 Unshielded Twisted Pair (UTP) Adv –Does not require grounding like STP, easier to add connectors –Thinner, more flexible to install –Same data speeds as other copper media Disadv –More susceptible to electrical noise and interference –Shorter cabling distance (100m when used for Ethernet LANs)

17. CIM 2465 Network Connectivity17 Twisted Pair Wire Advantages –Commonly available and relative low cost, especially where telephone lines have already been installed Disadvantages –Subject to signal distortion, noise and interference, and the relatively low transmission rates

18. CIM 2465 Network Connectivity18 Fiber Optic Cable Thin wire (usually very pure glass or plastic) surrounded by a reflective cladding that is used to transmit optical signals (light) Copper wire cables transmit signals electrically, whereas fiber-optic cables transmit signals by means of light More expensive than copper wires, more skill to install

19. CIM 2465 Network Connectivity19 Fiber Optic Cable

20. CIM 2465 Network Connectivity20 Fiber Optic Cable Not susceptible to lightning, electromagnetic interference (EMI), or radio frequency interference (RFI), and does not generate EMI or RFI Much greater bandwidth Greater transmission distances Excellent signal quality

21. CIM 2465 Network Connectivity21 Fiber Optic Cable More secure (difficult to tap) Thin, requires little space in a conduit Lightweight, easy to install Better resistance to environment factors, e.g. water Generally used to link LANs, WANs, or as backbone of large networks

22. CIM 2465 Network Connectivity22 Fiber Optic Cable Fiber Optics Types: –Multi-mode cable Less expensive Less expensive LED transmitters are used Larger core, multiple angles of entry –Single-mode cable More expensive More expensive laser transmitters are used Significant longer cabling distances Skinny core, only one angle of entry

23. CIM 2465 Network Connectivity23 Fiber Optic Cable

24. CIM 2465 Network Connectivity24 Wireless Media (1) Infrared Radio wave –Bluetooth –Wifi –Mobile Phone network (e.g. GSM, 3G) –Microwave –Satellite

25. CIM 2465 Network Connectivity25 Wireless Media (2) WLAN Components –PCs with WLAN NICs –Access Points (APs), which act as a LAN hub for wireless devices Infrastructure mode –Uses APs, with the PCs sending and receiving data to and from the AP Ad-hoc mode –Formed by any two wireless devices, find and associate with each other

26. CIM 2465 Network Connectivity26 Wireless Media (3) To install a WLAN that works with the existing LAN infrastructure –At least one AP –A straight-through cable to connect AP to an existing LAN switch –Wireless NICs in end-user devices to communicate with the APs

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28. CIM 2465 Network Connectivity28 Wireless Media (4) WLAN Organization and Standards –IEEE defines WLAN standards 802.11 –Wi-Fi alliance (www.wi-fi.org) StandardSpectrum UsedMax Data Rate 802.11a5GHz54Mbps 802.11b2.4GHz11Mbps 802.11g2.4GHz54Mbps

29. CIM 2465 Network Connectivity29 LAN Cabling Considerations –Ethernet Types –Media –Speed –Distance –Connector

30. CIM 2465 Network Connectivity30 LAN UTP Cabling Standards CategoryPurposeComments 1TelephonesNot suitable for data 2Token RingSupports 4Mbps Token Ring 3Telephones and 10BASE-T 4Token RingSupports 16Mbps Token Ring 5Ethernet10BASE-T and 100BASE-T 5eEthernetSupports Gigabit Ethernet 6EhernetOfficially supports 1Gbps, working for 10Gbps support

31. CIM 2465 Network Connectivity31 Ethernet LAN Media and Connectors Ethernet TypesMediaMax Segment Length Connector 10BASE250-ohm coax (Thinnet) 185mBNC 10BASE550-ohm coax (Thicknet) 500mAttachment unit interface (AUI) 10BASE-TCat 3,4,5 UTP100mRJ45 100BASE-TXCat 5 UTP100mRJ45 100BASE-FX62.5/125 micron multimode fiber 400mDuplex media interface connector (MIC), ST, or SC 1000BASE-TCat 5 UTP100mRJ45

32. CIM 2465 Network Connectivity32 UTP Cable Pinouts Key concepts –Ethernet devices (at 10 and 100Mbps Ethenet) use one pair of wires to transmit data –Ethernet devices (at 10 and 100Mbps Ethenet) use another pair of wires to receive data –Two pairs of wires are required Types –Straight-Through Cable –Crossover Cable –Console Connection and Rollover Cable

33. CIM 2465 Network Connectivity33 Straight-Through Cable To connect an end-user device and a LAN hub or switch PC’s NIC uses –Pin 1, 2 to transmit –Pin 3, 6 to receive LAN hubs, switches (the other end) –Pin 3, 6 to transmit –Pin 1, 2 to receive

34. CIM 2465 Network Connectivity34 Straight-Through Cable TIA/EIA-T568-B or A on BOTH ends of the cable

35. CIM 2465 Network Connectivity35 TIA/EIA 568-A

36. CIM 2465 Network Connectivity36 Crossover Cable To connect two devices that both want to send on the same pins (two devices of similar ‘type’, e.g. two PCs) BOTH sides use –Pin 1, 2 to transmit –Pin 3, 6 to receive

37. CIM 2465 Network Connectivity37 Crossover Cable One side is T568-A and T568-B one the other (10BaseT, 100BaseT) Special arrangement for 1000BaseT

38. CIM 2465 Network Connectivity38 How to choose? Two groups of devices –PC, router, server, AP (use pins 1 and 2 to transmit) –Switch, hub, bridge, repeater (use pins 3 and 6 to transmit) When connecting two devices that are similar in regard to which pins they use to transmit, use a crossover cable –e.g. Switch to Switch, Switch to Hub, Hub to Hub, Router to Router, PC to PC, Router to PC When connecting two devices that differ in regard to which pins they use to transmit, use a straight-through cable –e.g Switch to Router, Switch to PC, Hub to PC

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40. CIM 2465 Network Connectivity40 Basic Models for PC Communications (1) Peer-to-peer –A computer acts as a peer with other computer by acting both as a client and a server –E.g. Sharing a folder in a Windows workgroup –Adv Simple to install No special hardware required Most OS support peer-to-peer networking No network administrators required –Disadv Security Loss control

41. CIM 2465 Network Connectivity41 Basic Models for PC Communications (2) Client/Server –A computer acts as either a client or a server –Server usually is more powerful, and requires a more expensive network operating system (NOS) –Adv Centralized control Security control Easier data backup –Disadv Cost Network administrators required If server fails, ….

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43. CIM 2465 Network Connectivity43 Comparing Peer-to-Peer and Client/Server Comparison PointP-to-PC/S Requires a dedicated server Requires a more expensive NOS Requires a dedicated network administrator End users must be trained in network administration More secure Easier to back up data Scales well Single point of failure