1 ITEC 370 Network Media George Vaughan

2 Sources for Slides Material in these slides comes primarily from course text, Guide to Networking Essentials,Tomsho, Tittel, Johnson (2007). Other sources are cited in line and listed in reference section.

3 TCP/IP and OSI Models

4 Cable Characteristics Bandwidth – Bits per second Maximum Cable Length – Length before signal is unintelligible due to attenuation. Maximum Number of Segments – Maximum number of segments (including signal regeneration equipment) before signal is too late at destination. Maximum Number of Devices per Segment – Devices also increase attenuation (insertion loss). Interference Susceptibility – Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI). Connection Hardware – Cost, Complexity Cable Grade – Cladding or Sheath Material, Fire Codes, Usable in walls or plenum. Bend Radius – Degrees per feet Material Cost Installation Cost

5 Boadband and Baseband Communication Baseband –Uses a single frequency to transmit digital pulses. –Half Duplex per strand (2 strands for Full Duplex). –Bi-directional – one strand can be used for sending and receiving. –Repeaters and switches are used for signal regeneration. –Used in Ethernet Broadband –Analog Transmission –More than one frequency can be on one strand –A single strand can support Full Duplex –One frequency is unidirectional – 2 strands (Dual-Cable Broadband) or 2 frequencies (Mid-split broadband) needed for Full Duplex. –Amplifiers used to strengthen signals.

6 Cable Types - Coax Used by Cable TV No longer used in LANs Interference: better than twisted pair, worse than fiber Used in early Ethernet Applications –10Base5 (10 Mbps, Baseband, 500 meter segments) - Thicknet –10Base2 (10 Mbps, Baseband, 200 meter segments) - Thinnet –Used in Physical Bus Ethernet networks Cable Modem Applications –75 ohm, RG-6 (Radio Grade) –256 Kps up to 1 Mbps –Shared resource: more connections = lower bandwidth

7 Coaxial Cable (continued) Tomsho, Tittel, Johnson (2007)

8 Coaxial Cable in Cable Modem Applications (continued) Tomsho, Tittel, Johnson (2007)

9 Cable Types – Twisted Pair Twisted Pair (TP) – strand pairs are twisted around each other – minimizes interference and crosstalk. Unshielded Twisted Pair (UTP) –Ethernet: 10BaseT (10 Mbps, Basedband, UTP) – requires physical Star topology (Odom, 2006) –UTP most popular LAN cable –Also used in Phone Systems

10 Twisted-Pair Cable Tomsho, Tittel, Johnson (2007)

11 Cable Types – Twisted Pair Shielded Twisted Pair (STP) – similar to UTP, except that braided pair is contained in a foil. No standard exists for STP. UTP and STP usually use RJ-45 (Registered Jack) telephone connectors. RJ-45 contain 8 contacts, although, only 4 are used, 2 for transmit (+/- ) and 2 for receive (+/-) 2 different standards for wiring an RJ-45 connector: TIA/EIA 58A and TIA/EIA 58B Cable Wiring Strategies (Odom, 2006) –Straight Through Wiring: Pins (1,2) -> Pins (1,2) and Pins (3,6) -> Pins (3,6) Used for connecting PC’s to hubs or switches –Crossover Wiring: Pins (1,2) -> Pins (3,6) and Pins (3,6) -> Pins (1,2) Used for connecting PC’s to PC’s or switches to switches

12 Twisted-Pair Cable (continued) Tomsho, Tittel, Johnson (2007)

13 Cable Types – Fiber Optic Uses light rather than EM signals to transmit information. Not susceptible to EMI or RFI Does not broadcast or radiate EM signals Extremely secure to electronic eavesdropping. Very High Bandwidth: 10 Gb/s and greater Maximum cable segments on the order of miles. More fragile, less flexible than copper. More expensive. Each strand passes signals in one direction.

14 Fiber-Optic Cable Tomsho, Tittel, Johnson (2007)

15 Fiber-Optic Cable (continued) Tomsho, Tittel, Johnson (2007)

16 Single and Multi-Mode Fiber Information on this slide comes from (Odom, 2006) Multi-Mode: –Used with LEDs –LEDs spread light in multiple angles –LED light doesn’t travel as far as laser –Thicker core to absorb angular LED light Single-Mode –Used with Lasers –Lasers don’t spread light – single direction –Thinner core –Laser light travels further than with LED source

17 Cable Type Comparisons Comparison of cost and performance of different cable types (Tomsho, 2007)

18 Cable Considerations Plan network to separate light/moderate users from heavy users. Plan network to separate local traffic from backbone traffic A mixture of TP connected by hubs which are then interconnected by coax or fiber give TP greater reach Need to consider existing cable plant.

19 Structured Cabling Defines cable plant organization (TIA/EIA 568) Work Area work station environment, patch cables (<6 meters). Horizontal Wiring cabling from work area to Telecommunications Closet (<90 meters) Telecommunications Closet (TCs) patch panel, hubs, switches. Equipment Rooms servers, switches, routers Backbone Cabling that connects equipment rooms, TCs. Fiber often used. Entrance Facilities location where leased lines meet Enterprise network.

20 Telecommunications Closet Tomsho, Tittel, Johnson (2007)

21 Wireless LANs (WLAN) Standards are defined by Institute of Electrical and Electronics Engineers (IEEE) IEEE networking characteristics is similar to Ethernet (IEEE 802.3) Characteristics of (IEEE , n.d.)

22 The Wireless World (continued) Tomsho, Tittel, Johnson (2007)

23 Wireless MAN: The Standard Tomsho, Tittel, Johnson (2007) One of the latest wireless standards, Worldwide Interoperability for Microwave Access (WiMax), comes in two flavors: (previously named a), or fixed WiMax, and e, or mobile WiMax –Promise wireless broadband to outlying and rural areas, where last-mile wired connections are too expensive or impractical because of rough terrain –Delivers up to 70 Mbps of bandwidth at distances up to 30 miles –Operates in a wide frequency range (2 to 66 GHz)

24 References Tomsho, Tittel, Johnson (2007). Guide to Networking Essentials. Boston: Thompson Course Technology. Odom, Knott (2006). Networking Basics: CCNA 1 Companion Guide. Indianapolis: Cisco Press Wikipedia (n.d.). IEEE Retrieved 09/10/2006 from Wikipedia (n.d.). OSI Model. Retrieved 09/12/2006 from