1. Chapter 2

2.  Types of Network  Circuit Switched & Packet Switched  Signaling Techniques  Baseband & Broadband  Interference  Transmission Medium  Wired & wireless Prepared by Saher H. Mohammed2

3.  There are two kinds of networks over which data can be transmitted.  Circuit switched network  Packet switched network 3Prepared by Saher H. Mohammed

4.  In a circuit switched network, there is a dedicated and a direct physical connection between the sender and the receiver.  No other transmission can take place while the connection is active.  Once the current transmission is ended, other connections can be made.  Ideal for voice communication as no interruption from other devices. 4Prepared by Saher H. Mohammed

5.  This network requires data transmission be broken into smaller units called packets.  Each packet is sent independently through the network.  It is used for data transmission because data is not as time- sensitive as voice communication.  It allows multiple devices to share one line or frequency.  It facilitates error correction. 5Prepared by Saher H. Mohammed

6.  There are two ways to send a signal over a medium.  Baseband signaling  Broadband signaling 6Prepared by Saher H. Mohammed

7.  Sends one data signal across the network media.  Entire capacity of the media is used for the one data signal.  Signals are transmitted in a digital format.  Many devices can send and receive across the medium, but only one at a time.  Used for computer network data transmissions. 7Prepared by Saher H. Mohammed

8.  Divides the cable into several different channels.  Signals are transmitted at different frequencies in an analog mode.  Allows many different signals to be sent simultaneously on a single cable.  Signal sent in only one direction. 8Prepared by Saher H. Mohammed

9.  The flow of a signal down the network media can become distorted.  Common types of distortions are attenuation and interference. 9Prepared by Saher H. Mohammed

10.  Attenuation is the loss of signal power.  Measured by the decrease in decibels (db) over a specific distance. 10Prepared by Saher H. Mohammed

11.  Interference is caused when a strong external signal interferes with a signal.  Radio frequency interference (RFI) is an interference caused by broadcast signals from a radio or television transmitter.  Electromagnetic interference (EMI) when motor or source of intense electrical activity creates an electromagnetic signal that interferes with a data signal.  Near end crosstalk (NEXT) and Far end crosstalk (FEXT) - interference from another data signal being transmitted on adjacent wire. 11Prepared by Saher H. Mohammed

12.  Media is the base for communication between devices.  Coaxial cables (coax).  Twisted Pair cable.  Fiber optic cables.  Wireless. 12Prepared by Saher H. Mohammed

13.  Coaxial cables are very common in connecting TV’s to cable services or satellite.  It is used in these areas because of its high bandwidth and shielding capabilities.  Coax cables are less prone to the external interferences, but very costly to run. 13Prepared by Saher H. Mohammed

14. 14Prepared by Saher H. Mohammed

15.  Twisted-pair cables have replaced the coax cables in the Ethernet networks.  Twisted-pair cables use the same technology used by the phone company for the movement of electrical signals.  Twisted-pair cables come if two forms,  Unshielded Twisted-pair cables  Shielded Twisted-pair cables 15Prepared by Saher H. Mohammed

16.  Shielded twisted-pair Cable (STP) has a foil shield around the pairs to provide extra shielding from electromagnetic interference.  Unshielded twisted-pair Cable (UTP) has no such foil around it. It uses the actual twists to eliminate interference.  STP provides better communication, but it is expensive compared to UTP. 16Prepared by Saher H. Mohammed

17.  The standard method of connecting twisted-pair cables is via a 8-pin connector called RJ-45 connector.  Twisted-pair cables are divided into three categories depending upon their transmission speed. DesignationCategoryDescription 10BaseTCategory 310 Mbps baseband Ethernet over twisted pair cable with a maximum length of 100 meters. 100BaseTCategory 5100 Mbps baseband Ethernet over twisted pair cable. 1000BaseTCategory 61000 Mbps baseband Ethernet over four pairs of category 5 unshielded twisted pair cables. 17Prepared by Saher H. Mohammed

18. 18Prepared by Saher H. Mohammed

19.  Fiber optic cable uses a beam of laser light to connect devices over a thin glass wire.  The biggest advantage of fiber optic cables is the higher bandwidth. These cables are used as a backbone to all the large networks and internet.  The biggest disadvantage of fiber optic cables is the cost. 19Prepared by Saher H. Mohammed

20.  Making connection to a fiber optic cable is very difficult/ impossible.  It is very difficult to splice a fiber optic. Making the precise connections on the end of fiber optic line is a highly skilled job and is done by a specifically trained professionals.  Once the connector is fitted on the end, several forms of connectors and blocks are used to make new connections. 20Prepared by Saher H. Mohammed

21. 21Prepared by Saher H. Mohammed

22. 22Prepared by Saher H. Mohammed

23.  Transmission is sent and received through invisible waves.  Unguided media is a phrase used to cover all transmission media not guided by wire or fiber.  Unguided media includes radio frequency (RF), infrared (IR) and microwave methods. 23Prepared by Saher H. Mohammed

24.  Unguided media have one attribute in common, that they are unguided and can travel to many machines simultaneously.  Allows the user to move freely around the office or campus and still remain connected to the network.  Fastest-growing segment of network media today.  Less expensive than copper or fiber optic lines. 24Prepared by Saher H. Mohammed

25.  Radio Frequency (RF) is the most common and widely used method of wireless communication.  RF waves uses variety of frequency bands, each with special characteristics.  Microwave is used to describe a specific portion of the RF spectrum that is used for communication as well as other tasks such as cooking. 25Prepared by Saher H. Mohammed

26.  Advantages of Microwaves  Microwaves can penetrate through thick walls  Microwaves can propagate through rough terrain  Microwaves have broadcast capability  Microwaves provide cost-effective solutions 26Prepared by Saher H. Mohammed

27.  IR is a band of electromagnetic energy just beyond the red end of the visible spectrum.  IR is commonly used in remote control devices, wireless devices like printers, keyboards, mice and PDA’s.  Drawbacks of IR  Slow  Cannot penetrate thick walls 27Prepared by Saher H. Mohammed

28.  The NIC serves as the connection between the personal computer and the network media.  It connects to the computer on its base by plugging into an expansion slot of the computer.  Another connection is accessible from the outside of the computer and has connections for the cables to plug into the network. 28Prepared by Saher H. Mohammed

29. 29Prepared by Saher H. Mohammed