Unit 1 Introduction to WANs and Telecommunications

Transcription

1 Unit 1 Introduction to WANs and Telecommunications Chapters 1 from both textbooks Chapter 1: The Basics Sound, Electrical Signals, Electromagnetic Spectrum 2008 ITT Educational Services Inc. IT-320 Wan Technologies : Unit 1: Slide 1

2 Objectives In this unit, students will describe common WAN protocols and interfaces. Review the OSI reference model. Identify organizations responsible for WAN standards. Explain the difference between a WAN and LAN and the type of standards and protocols each uses. Describe the role of a router in a WAN. Review IP addressing and subnetting. Identify internal components of the router and describe their functions. Describe the physical characteristics of the router. Identify LAN and management ports on a router. Demonstrate proper connectivity of the Ethernet, WAN, and Console ports. Describe the transmission of data. Describe the electromagnetic spectrum. Describe telecommunications standards organizations. IT320 WAN Technologies: Unit 1: Slide 2

3 The Characteristics of Sound Sound is: An audible frequency created by a source. Transmitted over a medium. Medium: Carrier of something like sound or information Air carries sound. Water carries sound. IT320 WAN Technologies: Unit 1: Slide 3

4 Figure 1 1 Waves projecting from the source. IT320 WAN Technologies: Unit 1: Slide 4

5 Other Characteristics of Sound Frequency: The number of events that happen over a period of time Measured in the number of cycles per second, called Hertz Wavelength: The length of one complete waveform Amplitude: The measurement of the wave from top to bottom IT320 WAN Technologies: Unit 1: Slide 5

6 Figure 1 2 Five cps analog waveform projected onto a white screen. 5 cps analog waveform IT320 WAN Technologies: Unit 1: Slide 6

7 Figure 1 3 Comparison between a 5 cps analog signal and a 7 cps analog signal. Comparison between a 5 cps and a 7 cps analog waveform IT320 WAN Technologies: Unit 1: Slide 7

8 Figure 1 4 One wave of a 10 cps waveform measured from the beginning of the cycle to the end of the cycle or from the peak of one wave to the peak of the next wave. A 10 cps analog waveform measuring different points IT320 WAN Technologies: Unit 1: Slide 8

9 Figure 1 5 Abstract depiction of a typical waveform generated by human speech. An abstract of an analog waveform of human speech IT320 WAN Technologies: Unit 1: Slide 9

10 Figure 1 6 Voltage is used to measure the signal strength of various amplitudes. The greater the amplitude, the louder the sound and the stronger the signal. Voltages measured on an analog waveform IT320 WAN Technologies: Unit 1: Slide 10

11 Frequencies of Human Communication Sound ranges from 20 to 20,000 Hz. We hear in a range of Hz. Music utilizes the entire sound range of 20-20,000 Hz. IT320 WAN Technologies: Unit 1: Slide 11

12 Sound and Electrical Waves We use electrical energy to create sound waves by matching the frequencies. Very quick electrical oscillators take the electrical waves and moves the air to produce the sound waves. Delay is always an issue because it takes time for the sound to be converted to energy, sent over a medium, and reconstructed as sound waves again. IT320 WAN Technologies: Unit 1: Slide 12

13 Figure 1 7 (a) A waveform of a defined frequency produced by sound compared with a waveform of the same frequency produced by an electronic transmitter. (b) DC voltage waveform. Comparing Electrical Waves to Sound Waves DC Voltage Waveform IT320 WAN Technologies: Unit 1: Slide 13

14 Voltage Basic Electricity in Circuits Applied to the wire to energize the electrons Current Movement of the electrons through the wire Impedance Factors that slow or hinder the flow of electrons through a wire Resistance A factor of impedance to measure the value that hinders electron flow IT320 WAN Technologies: Unit 1: Slide 14

15 (a) Alternating current (AC) waveform is the electrical power received from an AC outlet in a home. (b) Direct current (DC) is used to feed telephone equipment, telephone lines, and other telecommunications devices. Comparison between AC above and DC below IT320 WAN Technologies: Unit 1: Slide 15

16 Basic Electricity in Circuits (cont.) Capacitance The ability to store energy Inductance The ability to transfer energy Watts power Measurement of the results to electron flow Decibels Measure of the strength of a sound signal IT320 WAN Technologies: Unit 1: Slide 16

17 Figure 1 9 Analog waveform. Analog Waveform A two-dimensional representation of a three-dimensional action. IT320 WAN Technologies: Unit 1: Slide 17

18 Measuring any of these sounds using a db meter would result in values similar to these: IT320 WAN Technologies: Unit 1: Slide 18

19 Milliwatt values compared with dbm values For example, mw and -60 dbm represent the same value. Using -60 dbm to identify the strength of a signal is much simpler than using mw. IT320 WAN Technologies: Unit 1: Slide 19

20 Correlation between loss of dbm and frequency The greater the frequency, the greater the loss. Other variables also affect loss of circuit, such as the gauge of the cable. IT320 WAN Technologies: Unit 1: Slide 20

21 End-to-end circuit loss using dbm as the measurement value The total end-to-end loss of the circuit on this one-way termination is -8.5 dbm. At position C, the signal is regenerated, thus canceling out any loss up to that point. IT320 WAN Technologies: Unit 1: Slide 21

22 Commonly Used Values Prefix Abbreviation Value Nano n Micro u Milli m Kilo K Mega M ,000,000 Giga G ,000,000,000 Tera T ,000,000,000,000 Peta P ,000,000,000,000,000 IT320 WAN Technologies: Unit 1: Slide 22

23 IT320 WAN Technologies: Unit 1: Slide 23

24 Electromagnetic Spectrum Electromagnetic Waves Cannot be seen or touched but still exist Defined in the 1800s We use the Gauss and Faraday laws and Maxwell s formulas to measure them. Frequencies and the Electromagnetic Spectrum Grouped into bands of frequencies AM and FM typically IT320 WAN Technologies: Unit 1: Slide 24

25 Lines of force surround the earth and are tied together at the North and South poles. IT320 WAN Technologies: Unit 1: Slide 25

26 IT320 WAN Technologies: Unit 1: Slide 26 Frequency Spectrum

27 Standards Organizations, Forums & Groups ITU: International Telecommunications Union ANSI: American Nation Standards Institute ISO: International Standards Institute IEEE: Institute of Electrical and Electronic Engineers IRTF: Internet Engineering Task Force NFOEC: National Fiber Optic Engineering Consortium OEC: Optical Engineering Consortium ATM: Asynchronous Transfer Mode Forum SONET: Synchronous Optical Network Forum OBF: Ordering and Billing Forum NANC: North American Numbering Council NPA: Numbering Planning Area IANA: Internet Assigned Numbering Authority ARIN: American Registry of Internet Numbers DARPA: Defense Advanced Research Projects Agency IT320 WAN Technologies: Unit 1: Slide 27

28 Take a Break 15 Min ITT Educational Services Inc. IT-320 Wan Technologies : Unit 1: Slide 28

29 Routers and Routing Basics CCNA 2 WANs and Routers Chapter ITT Educational Services Inc. IT-320 Wan Technologies : Unit 1: Slide 29 29

30 Objectives Introduction to Routing over WANs Connecting routers to WAN links Creating inexpensive leased lines in a lab Overview of routing over WANs Router hardware and software components Router Components and Cabling Internal router components External router interfaces Router management ports IT320 WAN Technologies: Unit 1: Slide 30 30

31 Routing over WANs Routers route Simple but true. That s their basic function. Layer 3 devices They work up through Layer 3 of the OSI Model Various levels of routers There are five levels of routers. We most typically use a level 5 router, which is the simplest form. A level 1 is often found linking large infrastructures. IT320 WAN Technologies: Unit 1: Slide 31

32 IP Routing, a Layer 3 Perspective 1. The Web server needs to send a packet to the computer on the right ( ), so the Web server sends the packet to its default gateway router namely, R1. 2. R1 decides to forward the packet to R2 next, based on R1 s routing table. 3. R2 s routing table shows that should be on a subnet directly connected to R2, so R2 knows to send the packet directly to the destination ( ). IT320 WAN Technologies: Unit 1: Slide 32 32

33 IP Routing and Layer 2 Encapsulation 1. IP packet encapsulated in an Ethernet frame to send the packet to its default gateway (R1). 2. R1 de-encapsulates the packet by extracting the packet from the received Ethernet frame. After R1 has decided to forward the packet out interface S0/0/0, R1 must encapsulate the packet in the correct data-link frame for that link in this case, a PPP frame. 3. R2 de-encapsulates (removes) the IP packet from the PPP frame. After R2 knows that it needs to forward the packet over an Ethernet LAN out interface Fa0/0, R2 encapsulates the IP packet in a new frame before sending the data over the Ethernet on the right. IT320 WAN Technologies: Unit 1: Slide 33 4

34 Connecting Routers to WAN Links Step 1: Order the leased line from a telco or other company that sells such services. Step 2: Order a router and a CSU/DSU for each of the two sites. Step 3: Physically install the router and CSU/DSU at each site. Step 4: Connect the router and CSU/DSU to the line from the telco, at each site. IT320 WAN Technologies: Unit 1: Slide 34 34

35 WAN Clocking on DTE and DCE Devices Data circuit-terminating equipment (DCE) A device that connects to the leased line provided by the telco. The DCE usually provides clocking to the DTE. Data terminal equipment (DTE) A device that sends data over a circuit. Routers act as DTEs. The DTE expects to receive clocking from the DCE. Clocking, or synchronization. The serial links used between two routers typically use synchronous communication (both sides use exact same speed for sending and receiving bits). IT320 WAN Technologies: Unit 1: Slide 35 6

36 WAN Standards Organizations IT320 WAN Technologies: Unit 1: Slide 36 7

37 WAN Standards at Layers 1 and 2 IT320 WAN Technologies: Unit 1: Slide 37 8

38 Creating Leased Lines in a Lab Step 1: Get two routers, each with a serial interface. Step 2: For one router, use a serial DTE cable. The connector on one end of the cable should be connected to one of the router s serial interfaces. Step 3: For the other router, use a serial DCE cable. The connector on one end of the cable should connect to the second router s serial interface. Step 4: Connect the DTE and DCE cables together. The DTE cable has a male connector, and the DCE cable has a female connector. (Make sure that both the DTE and DCE cables have the same type of connector so that they will connect to each other.) Step 5: Enable clocking on the router that is connected to the DCE cable so that the router takes the place of the telco and CSU/DSU by providing clocking to the other router. IT320 WAN Technologies: Unit 1: Slide 38 9

39 Creating Leased Lines in a Lab (Continued) Router as DCE: Back-to-Back Serial Links V.35 DTE and DCE Cable Connectors IT320 WAN Technologies: Unit 1: Slide 39 10

40 Overview of Routing over WANs Routing The process of forwarding packets Path selection When multiple possible routes to reach a subnet exist, routers must choose the best route or path over which to reach the subnet. This process can be referred to as path determination, or path selection. Dynamic and static routes Routers may learn or select routes either dynamically, using routing protocols, or statically, with the engineer configuring the routers with routing information. Logical addressing Routers rely on the logical addressing defined by Layer 3 protocols. Layer 3 addressing (IP addressing) allows addresses to be grouped for easier routing, which aids the process of end-to-end packet delivery by routers. IT320 WAN Technologies: Unit 1: Slide 40 11

41 Path Selection When a router learns about multiple paths to reach a particular subnet, the router must pick the best route, typically based on the routing protocol metric for each router. IT320 WAN Technologies: Unit 1: Slide 41 12

42 Router Hardware and Software A router is a computer that is designed for the specialized purpose of routing packets. Cisco IOS (Internetwork Operating System) is software that includes all the specialized features needed by routers, including routing protocols, basic routing logic, and support. Routers have physical network interfaces (like PC s NIC). Routers typically do not have a disk drive. IT320 WAN Technologies: Unit 1: Slide 42 13

43 Router Internal Hardware Components IT320 WAN Technologies: Unit 1: Slide 43 14

44 Router Internal Hardware Components (Continued) IT320 WAN Technologies: Unit 1: Slide 44 15

45 Internal Router Components Inside of a Cisco 2600 Router IT320 WAN Technologies: Unit 1: Slide 45 16

46 Logic Diagram of the Internal Components of a Cisco 2600 Series Router IT320 WAN Technologies: Unit 1: Slide 46 17

47 Internal Router Components IT320 WAN Technologies: Unit 1: Slide 47 18

48 Key Internal Router Components (Continued) IT320 WAN Technologies: Unit 1: Slide 48 19

49 External Router Interfaces Interfaces on a Cisco 2600 Series Router IT320 WAN Technologies: Unit 1: Slide 49 20

50 Cabling Ethernet LAN Interfaces IT320 WAN Technologies: Unit 1: Slide 50 21

51 Router Interfaces and Ports IT320 WAN Technologies: Unit 1: Slide 51 22

52 Cabling WAN Interfaces for Leased Lines IT320 WAN Technologies: Unit 1: Slide 52 23

53 Circuit-Switched WAN Using Modems 1. Router R1 places a phone call to router R2, creating a circuit between R1 and R2. 2. R1 and R2 exchange packets over the circuit. 3. When R1 has finished sending all the data it wants to send, R1 does the equivalent of hanging up the phone by terminating the call. 4. R1 can then call R3 to send data. IT320 WAN Technologies: Unit 1: Slide 53 24

54 Packet-Switched WAN: Frame Relay 1. R1 sends a frame with address 102 to the Frame Relay network. 2. The switches in the Frame Relay network know that address 102 means that the frame should be sent to router R2, so the switches forward the frame correctly. 3. R1 now needs to send data to R3, so R1 sends a frame into the Frame Relay network, this time with address 103 in the frame header. 4. The switches in the Frame Relay network know that address 103 means that the frame should be sent to router R3, so the switches forward the frame correctly. IT320 WAN Technologies: Unit 1: Slide 54 25

55 Router Management Ports Most routers have two management ports: the console port and the auxiliary port (aux port). (Some routers do not have aux ports.) Both ports are meant to allow a terminal, or more likely, a PC with a terminal emulator, to log in to the router to issue commands on the router. Terminal emulator software creates a window on the screen of a PC with any text you type on the keyboard (typically a command). IT320 WAN Technologies: Unit 1: Slide 55 26

56 Using a Terminal Emulator and a Router IT320 WAN Technologies: Unit 1: Slide 56 27

57 Accessing a Router Console Port IT320 WAN Technologies: Unit 1: Slide 57 28

58 HyperTerminal Configuration Settings 9600 bps 8 data bits No parity 1 stop bit No flow control IT320 WAN Technologies: Unit 1: Slide 58 29

59 Cabling a Router Auxiliary Port IT320 WAN Technologies: Unit 1: Slide 59 30

60 Out-of-Band Access to Remote Router 1. The link between R1 and R2 fails. 2. The telnet from the core engineer s PC fails. 3. The core site engineer can use a modem to call the remote router (R2) via the remote router s aux port. 4. Alternatively, if an engineer is at the remote site, the remote site engineer can access R2 via the console port. IT320 WAN Technologies: Unit 1: Slide 60 31

61 Comparison of Console and Auxiliary Ports IT320 WAN Technologies: Unit 1: Slide 61 32

62 Summary The major difference between a WAN and a LAN are protocols used on the lower layers. A LAN connects workstations, printers, servers, and other devices within a building or other small area. A WAN is used to connect multiple LANs, typically over a large geographic area. WANs operate at the physical layer (OSI Layer 1) and the data link layer (OSI Layer 2). Routers understand the Layer 1 and 2 details of both LANs and WANs, plus they use Layer 3 routing logic. IT320 WAN Technologies: Unit 1: Slide 62 33

63 Summary (Continued) Main Router Components Cisco IOS The OS that runs on Cisco routers CPU Executes instructions in the OS RAM or DRAM Stores items used for the router s work, such as the routing table NVRAM Stores the initial (startup) configuration file Flash memory Acts as permanent memory, typically holding the Cisco IOS software ROM Holds the bootstrap program and POST diagnostic programs LAN interfaces Can be used to receive and forward packets WAN interfaces Can be used to receive and forward packets Management ports Include the router s console and auxiliary ports and can be used to access the router s CLI IT320 WAN Technologies: Unit 1: Slide 63 34

64 Summary (End) In this unit, we: Described common WAN protocols and interfaces. Reviewed the OSI reference model. Identified organizations responsible for WAN standards. Explained the difference between a WAN and LAN and the type of standards and protocols each uses. Described the role of a router in a WAN. Reviewed IP addressing and subnetting. Identified internal components of the router and described their functions. Described the physical characteristics of the router. Identified LAN and management ports on a router. Demonstrated proper connectivity of the Ethernet, WAN, and Console ports. Described the transmission of data. Described the electromagnetic spectrum. Described telecommunications standards organizations. IT320 WAN Technologies: Unit 1: Slide 64