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AtmDirector, Browse with Me, CCDA, CCDE, CCDP, CCIE, CCNA, CCNP, CCSI, CD-PAC, CiscoLink, the Cisco NetWorks logo, the Cisco Powered Network logo, Cisco Systems Networking Academy, Fast Step, Follow Me Browsing, FormShare, FrameShare, GigaStack, IGX, Internet Quotient, IP/VC, iQ Breakthrough, iQ Expertise, iQ FastTrack, the iQ logo, iQ Net Readiness Scorecard, MGX, the Networkers logo, Packet, RateMUX, ScriptBuilder, ScriptShare, SlideCast, SMARTnet, TransPath, Unity, Voice LAN, Wavelength Router, and WebViewer are trademarks of Cisco Systems, Inc.; Changing the Way We Work, Live, Play, and Learn, Discover All That’s Possible, and Empowering the Internet Generation, are service marks of Cisco Systems, Inc.; and Aironet, ASIST, BPX, Catalyst, Cisco, the Cisco Certified Internetwork Expert Logo, Cisco IOS, the Cisco IOS logo, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Enterprise/Solver, EtherChannel, EtherSwitch, FastHub, FastSwitch, IOS, IP/TV, LightStream, MICA, 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51 52 53 54 55 56 OVERVIEW 1.1 CCNA BASICS OVERVIEW Overview 1.1.1 Course Objectives .5 1.1.2 Learner Skills and Requirements 1.1.3 Learner Responsibilities 1.1.4 Course Road Map .8 1.1.5 Icons and Symbols .9 1.2 COMPUTING BASICS 10 Overview 10 1.2.1 PC Components 11 1.2.2 PC vs Laptop 15 1.2.3 Network Interface Card .16 1.2.4 NIC Installation 18 1.2.5 Bit and Bytes (Measurement Terms) 19 1.2.6 Decimal-to-Binary Conversion 21 1.2.7 Binary-to-Decimal Conversion 23 1.2.8 Hex-to-Binary Conversion 25 1.2.9 Binary-to-Hex Conversion 27 Summary 30 1.3 NETWORKING FUNDAMENTALS 31 Overview 31 1.3.1 Basic Networking Terminology 32 1.3.2 Networking Applications 34 1.3.3 Why Network Computers? 36 1.3.4 The OSI Model 38 1.3.5 The OSI Layers and Functions 40 1.3.6 Data Communication .43 1.3.7 The TCP/IP Model 47 1.3.8 OSI Model vs TCP/IP Model .49 Summary 51 1.4 NETWORK DEVICES 52 Overview 52 1.4.1 Layer Devices 53 1.4.2 Layer Devices 56 1.4.3 Layer Devices 59 1.4.4 Firewalls and AAA Servers 61 1.4.5 Others 62 Summary 65 1.5 NETWORK TOPOLOGIES .66 Overview 66 1.5.1 Physical vs Logical 67 1.5.2 Bus 69 1.5.3 Star and Extended Star 70 1.5.4 Ring 72 1.5.5 Mesh and Partial Mesh 74 Summary 75 SUMMARY .76 57 1-2 Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 Overview In this introductory module, you will first look at the course overview, which gives the course objectives and course outline Then you will look at the components of a computer and at the role of computers in a networking system You will use the "ground-up" approach to learning networking, starting with the most basic component of a network—the computer The more you know about computers, the easier it will be to understand networks and how they are designed and built This module also explains how standards ensure greater compatibility and interoperability between various types of network technologies It discusses the basic functions that occur at each layer of the Open System Interconnection (OSI) reference mode and how information or data makes its way from application programs (such as spreadsheets) through a network medium (such as wires) to other application programs located on other computers on a network Network devices are products used to connect networks As computer networks grow in size and complexity, so the network devices used to connect them This module discusses the network devices that operate at different OSI layers In addition, it covers the Transmission Control Protocol/Internet Protocol (TCP/IP) reference model and the different types of network topologies Upon completing this module, you will be able to: 81 82 83 ■ Identify the major components of a computer system, and convert a binary number to a decimal number, a binary number to a hexadecimal number, and vice versa 84 85 86 ■ Define basic networking terminology and describe the benefits and functions of the OSI reference model and TCP/IP model, as well as the basic process of communication between layers of the OSI reference model 87 88 89 90 ■ Describe the functions, features, and operation of network devices used at Layers 1, 2, and of the OSI model, including bridges, hubs, switches, routers, firewalls and Authentication, Authorization, and Accounting (AAA) servers, and remote access severs 91 ■ Describe the features of different types of the network topologies 92 93 94 95 Outline This module contains these lessons: ■ Overview 96 ■ CCNA Basics Overview 97 ■ Computing Basics 98 ■ Networking Fundamentals 99 ■ Network Devices 100 ■ Network Topologies 101 ■ Summary Copyright 2002, Cisco Systems, Inc Module 1: Introduction to Networking 1-3 1.1 CCNA Basics Overview 102 Overview 103 104 105 106 107 CCNA Basics is a self-paced interactive course that explains fundamental networking technologies Each module is designed to build upon information learned in the previous module Completion of the entire course, including review modules, should last approximately 24 hours Outline 108 109 110 111 This module contains these lessons: ■ Overview 112 ■ Course Objectives 113 ■ Learner Skills and Requirements 114 ■ Learner Responsibilities 115 ■ Course Road Map 116 ■ Icons and Symbols 117 118 119 1-4 Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 119 120 121 122 123 124 1.1.1 Course Objectives Upon completing this course, you will be able to perform the following overall tasks: ■ Describe computer hardware basics, binary and hexadecimal number systems, basic networking terminology, and internetworking concepts 125 126 127 ■ Identify the major components of a network system, including clients and servers, network interface cards (NICs), internetworking devices, media, and topologies 128 129 130 131 ■ Describe the functions, operations, and primary components of local-area networks (LANs), metropolitan-area networks (MANs), wide-area networks (WANs), virtual private networks (VPNs), intranets, extranets, storage-area networks, and content-delivery networks (CDNs) 132 133 ■ Define the major network access methods and outline the key features of each 134 ■ Describe the functions and operations of switching technologies 135 136 ■ Explain the purposes of networking addresses, routing protocols, and routed protocols 137 138 139 ■ Explain the format and significance of each of the following components to a network system: IP addressing, classes, reserved address space, and subnetting 140 141 ■ Calculate valid subnetwork addresses and mask values such that user/network requirements are met when given an IP address scheme 142 143 ■ Describe the functions, operations, and primary components of WAN technologies 144 145 ■ Describe the function, operation, and primary components required to provide remote access services 146 147 ■ Describe the functions, operations, and primary components of wireless technologies 148 149 ■ Describe the functions, operations, and primary components of optical networking 150 ■ Explain the purposes and techniques for voice, data, and video convergence 151 152 153 154 155 156 Copyright 2002, Cisco Systems, Inc Module 1: Introduction to Networking 1-5 1.1.2 Learner Skills and Requirements 156 157 158 159 160 161 162 163 164 165 166 167 The CCNA Basics course focuses on introducing networking techniques, terminology, and technology CCNA Basics is the prerequisite for Interconnecting Cisco Network Devices (ICND), which is the recommended training path for individuals seeking certification as a Cisco Certified Network Associate (CCNA® expert) ICND presents the concepts, commands, and practice required to configure Cisco switches and routers To fully benefit from CCNA Basics, you must have the following prerequisite skills and knowledge: ■ Basic computer literacy 168 ■ Basic understanding of PC hardware 169 ■ Basic understanding of PC software 170 ■ Basic understanding of networking business drivers 171 172 173 1-6 Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 1.4.5 Others 1723 1724 Figure 1: Cisco AS5400 Series Universal Gateway 1725 1726 1727 Figure 2: Cisco DSLAM 6100 1728 1729 1-62 Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 Figure 3: Optical Platform – 15454 DWDM Gateway A gateway is a special-purpose device that performs an application-layer conversion of information from one protocol stack to another The Cisco AS5400 Series provides cost-effective platforms that combine routing, remote access, voice gateway, firewall, and digital modem functionality Figure [1] shows a Cisco AS5400 Series Universal Gateways which offers unparalleled capacity in only two rack units (RUs) with universal port data, voice, wireless, and fax services on any port at any time High-density, low power consumption, and universal port digital signal processors (DSPs) make Cisco AS5400 Series Universal Gateways ideal for many network deployment architectures, especially co-location environments and mega points of presence (POPs) DSLAM A digital subscriber line access multiplexer (DSLAM) is a device used in a variety of DSL technologies A DSLAM serves as the point of interface between a number of subscriber premises and the carrier network Figure [2] shows a Cisco 6100 series advanced DSL access multiplexer Optical Platforms Currently several optical platforms are available on the market for the optical network Figure [3] shows a Cisco ONS 15454 dense wavelength-division multiplexing (DWDM) system The Cisco ONS 15454 is the industry's leading metro optical transport platform, with over 600 customers and 30,000 systems deployed worldwide The ONS 15454 combines supercharged SONET/SDH transport, integrated optical networking including ITU Grid Wavelengths and DWDM, unprecedented multiservice interfaces on demand including Ethernet, ATM and TDM to deliver radical economic benefits to service providers The ONS 15454 provides the functions of multiple network elements in a single platform Part of Cisco's unrivaled IP+Optical product line, the ONS 15454 combines the capacity of optical transport with the intelligence of IP to cost effectively deliver next generation voice and data services Copyright 2002, Cisco Systems, Inc Module 1: Introduction to Networking 1-63 1766 Practice 1767 1768 Which of the following statements is correct? 1769 1770 A A gateway is a special-purpose device that performs an applicationlayer conversion of information from one protocol stack to another 1771 1772 1773 B Cisco AS5400 Series Universal Gateways offers unparalleled capacity in only two RUs with universal port data, voice, wireless, and fax services on any port at any time 1774 1775 C A DSLAM serves as the point of interface between a number of subscriber premises and the carrier network 1776 D All of the above ** 1777 1778 1779 1-64 Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 1779 1780 1781 1782 1783 1784 Summary This section summarizes the key points you learned in this lesson ■ Networking devices are products used to connect networks Hubs, switches, and routers interconnect devices within LANs, MANs, and WANs They function at different layers of the OSI model 1785 1786 ■ Repeaters reshape, amplify, and re-time signals before sending them on along the network 1787 1788 1789 1790 1791 ■ The term hub is used instead of repeater when referring to the device that serves as the center of a network Hubs work at Layer only and make no decisions A hubs-only environment is a shared-access environment within which collisions occur As devices are added to the network, more and more collisions occur and performance declines dramatically 1792 1793 ■ Layer LAN switches work at Layer and make limited MAC hardware address decisions Ethernet switches provide dedicated LAN connections 1794 1795 1796 1797 ■ Multilayer switches work at Layers 2, 3, and and enable Layer QoS and security functionality to be implemented Multilayer switches perform many of the same functions as routers (explained in the next lesson), but they so in hardware 1798 1799 ■ Routers can make intelligent decisions as to the best path for delivery of data on the network 1800 1801 ■ Various types of servers provide services to computers and users accessing the network 1802 ■ Firewalls and AAA servers provide security to the network 1803 1804 Copyright 2002, Cisco Systems, Inc Module 1: Introduction to Networking 1-65 1805 1.5 Network Topologies 1806 Overview 1807 1808 1809 This lesson describes physical and logical topologies and discusses various topologies used in networking Objectives 1810 1811 1812 1813 Upon completing this lesson, you will be able to: ■ Define physical topology and logical topology 1814 ■ Define and discuss bus topology 1815 ■ Define and discuss star and extended-star topologies 1816 ■ Define and discuss ring topology 1817 ■ Define and discuss mesh and partial-mesh topologies Outline 1818 1819 1820 1821 This lesson includes these sections: ■ Overview 1822 ■ Physical vs Logical 1823 ■ Bus 1824 ■ Star and Extended Star 1825 ■ Ring 1826 ■ Mesh and Partial Mesh 1827 ■ Summary 1828 1829 1-66 Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 1829 1.5.1 Physical vs Logical 1830 Figure 1: Physical Topologies 1831 1832 1833 Figure 2: Teaching Topologies 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 The network topology defines the way in which the computers, printers, and other devices are connected In other words, the topology of a network describes the layout of the wire and devices as well as the paths used by data transmissions The topology greatly influences the way the network works Networks can have both a physical and a logical topology (see Figures [1] and [2]) ■ Copyright 2002, Cisco Systems, Inc Physical topology: Refers to the layout of the devices and media Module 1: Introduction to Networking 1-67 1844 1845 1846 ■ 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 Logical topology: Refers to the paths that signals travel from one point on the network to another (that is, the way in which data accesses media and transmits packets across it) The physical and logical topologies of a network can be the same For instance, in a network physically shaped as a linear bus, the data travels in a straight line from one computer to the next Hence, it has both a bus physical topology and a bus logical topology A network can also have physical and logical topologies that are quite different For example, a physical topology in the shape of a star, where cable segments can connect all computers to a central hub, can, in fact, have a logical ring topology Remember that in a ring, the data travels from one computer to the next That is because inside the hub, the wiring connections are such that the signal actually travels around in a circle from one port to the next, creating a logical ring Therefore, you cannot always predict how data travels in a network by simply observing its physical layout As for Ethernet and Token Ring, Token Ring uses a logical ring topology in either a physical ring or physical star, whereas Ethernet uses a logical bus topology in either a physical bus or physical star In the following sections, you will learn about the different types of topologies, including bus, star, ring, and mesh Practice 1868 1869 1870 1871 1872 1873 1874 1875 1876 Which of the following correctly describes networking topology? A The network topology defines the way in which the computer, printers, and other devices are connected ** B Networks can have either a physical or a logical topology C A physical topology describes the paths that signals travel from one point on the network to another D A logical topology defines the layout of the device and media 1877 1-68 Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1.5.2 Bus Figure 1: Bus Topology Commonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable, which proceeds from one computer to the next like a bus line going through a city The main cable segment must end with a terminator that absorbs the signal when it reaches the end of the line or wire If there is no terminator, the electrical signal representing the data bounces back at the end of the wire, causing errors in the network Only one packet of data can be transmitted at a time If more than one packet is transmitted, they collide and have to be resent A bus topology with many hosts can be very slow because of the collisions Practice Which of the following statement best describe but topology? A B C D All of its nodes connected directly to a central point All of its nodes connected directly to one physical link ** All of its nodes connected to each other All of its nodes connect to exactly other nodes 1898 Copyright 2002, Cisco Systems, Inc Module 1: Introduction to Networking 1-69 1898 1.5.3 Star and Extended Star 1899 Figure 1: Star Topology 1900 1901 1902 Figure 2: Extended-Star Topology 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 Star Topology [1] The star topology is the most commonly used architecture in Ethernet LANs When installed, the star topology resembles spokes in a bicycle wheel It is made up of a central connection point that is a device, such as a hub, switch, or router, where all the cabling segments actually meet Each host in the network is connected to the central device with its own cable Although a star topology costs more to implement than the bus topology because more cable is used and a central device such as a hub, switch, or router is needed, the advantages of a star topology are worth the additional costs Because each host is connected to the central device with its own wire, when there is a problem with that cable, only that host is affected The rest of the network is operational This benefit is extremely important and the reason why virtually every newly designed network has this topology 1-70 Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 Extended-Star Topology [2] When a star network is expanded to include an additional networking device connected to the main networking device, it is called an extended-star topology Most larger networks, such as those for corporations or schools, use the extendedstar topology This topology when used with network devices that filter data packets, such as switches and routers, significantly reduces the traffic on the wires by sending packets only to the wires of the destination host Practice Which topology has all its nodes connected directly to one center point, and has no other connections between nodes? A B C D Bus Ring Star ** Mesh 1936 Copyright 2002, Cisco Systems, Inc Module 1: Introduction to Networking 1-71 1.5.4 Ring 1936 1937 Figure 1: Ring Topology 1938 1939 1940 Figure 2: Dual-Ring Topology 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 The ring topology is another important topology in LAN connectivity As the name implies, hosts are connected in the form of a ring or circle Unlike the bus topology, it has no beginning or end that needs to be terminated Data is transmitted in a way unlike either the bus or the star topology A frame travels around the ring, stopping at each node If a node wants to transmit data, it adds that data as well as the destination address to the frame The frame then continues around the ring until it finds the destination node, which takes the data out of the frame The advantage of using this type of method is that there are no collisions of data packets There are two types of rings: 1957 1958 1959 1-72 ■ Single ring: All the devices on the network share a single cable, and the data travels in one direction only (see Figure [1]) Each device waits its turn to send data over the network ■ Dual ring: Two rings allow data to be sent in both directions (see Figure [2]) This setup creates redundancy (fault tolerance), meaning that if one ring fails, data can be transmitted on the other ring Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 The most common implementation of the ring topology is in Token Ring networks The IEEE 802.5 standard is the Token Ring access method used Fiber Distributed Data Interface (FDDI) technology is a similar to Token Ring, but it uses light instead of electricity to transmit data It uses the dual ring Practice What is the purpose of the second ring in a dual ring network? A B C D Duplex Signaling Redundancy ** None of the above 1974 Copyright 2002, Cisco Systems, Inc Module 1: Introduction to Networking 1-73 1.5.5 Mesh and Partial Mesh 1974 1975 Figure 1: Full-Mesh Topology 1976 1977 1978 Figure 2: Partial-Mesh Topology 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 Full-Mesh Topology [1] The full-mesh topology connects all devices (nodes) to each other for redundancy and fault tolerance Implementing the full-mesh topology is expensive and difficult Partial-Mesh Topology [2] In a partial-mesh topology, at least one device maintains multiple connections to others, without being fully meshed Practice 1989 1990 1991 1992 1993 1994 1995 1996 In a complete, or full-mesh, topology, every node: A B C D 1-74 Is linked directly to every other node ** Is connected to two central nodes Is linked wirelessly to a central node None of the above Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc 1996 1997 1998 1999 2000 2001 Summary This section summarizes the key points you learned in this lesson ■ A physical topology describes the plan for wiring the physical devices, and a logical topology describes how information flows through a network 2002 ■ In a bus topology, al the devices are connected by one single cable 2003 2004 2005 ■ The most commonly used architecture in Ethernet LAN is the star topology In a star topology, each host in the network is connected to the central device with its own cable 2006 2007 2008 ■ When a star network is expanded to include additional networking devices connected to the main networking device, it is called an extended star topology 2009 2010 2011 ■ In a ring topology, all the hosts are connected in the from of a ring or circle Token Ring networks use ring topology, whereas FDDI uses the dual-ring topology 2012 ■ A full-mesh topology connects all devices to each other 2013 2014 2015 Copyright 2002, Cisco Systems, Inc Module 1: Introduction to Networking 1-75 Summary 2016 2017 2018 2019 2020 This module included these key points: ■ Computers are important building blocks in a network Thus, it is important to be able to recognize and name the major components of a PC 2021 2022 ■ A network interface card (NIC) provides network communication capabilities to and from a PC 2023 2024 2025 ■ The binary, or Base 2, number system uses two digits to express any numerical quantity The only digits used in the binary number system are and 2026 2027 2028 ■ The hexadecimal, or Base 16, number system is used frequently when working with computers, because it can be used to represent binary numbers in a more readable form 2029 2030 2031 ■ One of the purposes of an internetwork is to increase productivity by linking computers and computer networks so that people have access to data anytime, anywhere 2032 2033 2034 ■ The OSI reference model is a descriptive network scheme whose standards ensure greater compatibility and interoperability between various types of network technologies 2035 2036 ■ The OSI model layering precludes direct communication between peer layers in different systems 2037 2038 ■ A physical topology describes the plan for wiring the physical devices, and a logical topology describes how information flows through a network 2039 2040 ■ There are different types of physical topology They include: bus, star, extended star, ring, dual ring, full mesh, partial mesh and so on 2041 2042 2043 2044 2045 2046 2047 2048 1-76 Cisco Certified Network Associate Basics (CCNAB) v2.0 Copyright 2002, Cisco Systems, Inc ... data is transmitted from one part of a computer to another It connects all the internal computer components to the CPU The Industry-Standard Architecture (ISA) and the peripheral component interconnect... provides a port for connecting to the network It constitutes the computer interface with the LAN The NIC communicates with the network through a serial connection, and with the computer through a... devices used to connect them This module discusses the network devices that operate at different OSI layers In addition, it covers the Transmission Control Protocol/Internet Protocol (TCP/IP) reference