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Chapter 9 Network Basics Network Definition A network is a set of technologies that is used to connect computers The network allows communication and collaboration between users Networking is a group of technologies working together. These technologies include: Media is the wiring that connects the computers 2. Hardware needs to be installed to connect the media 3. Software needs to be written to handle networks 1. 9A-2 The Uses of a Network 1. Simultaneous access to data Network server is a central computer with large storage device and other resources that all users can share Data files are shared File servers Shared files stored on a server Access can be limited Software can be shared Application servers Site licenses Network versions 9A-3 Network server Users can share data stored on central server The Uses of a Network 2. Shared peripheral device Printers and Faxes are commonly shared Reduces the cost per user Devices can be connected to the network Print servers control network printing 9A-4 The Uses of a Network 3. Personal communication – Email • Instantaneous communication – Conferencing • Tele conferencing 1. Videoconferencing 2. Audio-conferencing 3. Data-conferencing – Voice over IP • Phone communication over network wires 9A-5 The Uses of a Network 4. Easier data backup Backup copies data to removable media Server data backed up in one step 9A-6 Assignment No. 2 What are the Network Operating Systems (NOS). Describe their roles? b) Comparison of features of Linux and Windows operating systems c) Write advantages and drawbacks of Internet in our life. (at least 5 each) a) Due date: 05 February, 2009 9A-7 Common Network Types Local Area Network (LAN) Contains printers, servers and computers Systems are close to each other Contained in one office or building Organizations often have several LANS Wide Area Networks (WAN) Two or more LANs connected Over a large geographic area Typically use public or leased lines Phone lines Satellite The Internet is a WAN 9A-8 Hybrid Network Types Metropolitan Area Network (MAN) Large network that connects different organizations Shares regional resources A network provider sells time Typically covers an area of between 5 and 50 km diameter Campus Area Networks (CAN) A LAN in one large geographic area Resources related to the same organization Each department shares the LAN 9A-9 LAN, MAN, WAN 9A-10 Hybrid Network Types Home Area Network (HAN) Small scale network Connects computers and entertainment appliances Found mainly in the home Personal Area Network (PAN) Very small scale network Range is less than 2 meters Cell phones, PDAs, MP3 players 9A-11 How Networks Are Structured Server based network Node is any network device Servers control what the node accesses Users gain access by logging in Server is the most important computer Client/Server network Nodes and servers share data roles Nodes are called clients Servers are used to control access Database software Access to data controlled by server 9A-12 How Networks Are Structured Peer to peer networks (P2P) All nodes are equal Nodes access resources on other nodes Each node controls its own resources Most modern OS allow P2P Network Distributing computing is a form of P2P Kazaa is a P2 Possible threats? 9A-13 Network Topologies Topology Logical layout of wires and equipment Choice affects Network performance Network size Network collision detection Packets 9A-14 Pieces of data transmitted over a network • Packets are created by sending node • Data is reassembled by receiving node Packet header • Sending and receiving address Packet payload • Number and size of data • Actual data Network Topologies 1. Bus topology – Also called linear bus – One wire connects all nodes – Terminator ends the wires – Advantages • Easy to setup • Small amount of wire – Disadvantages • Slow • Easy to crash 9A-15 Network Topologies 2. Star topology – All nodes connect to a hub • Packets sent to hub • Hub sends packet to destination – Advantages • Easy to setup • One cable can not crash network – Disadvantages • One hub crashing downs entire network • Uses lots of cable – Most common topology 9A-16 Network Topologies 3. Ring topology – Nodes connected in a circle – Tokens used to transmit data • Nodes must wait for token to send – Advantages • Time to send data is known • No data collisions – Disadvantages • Slow • Lots of cable 9A-17 Network Topologies 4. Mesh topology All computers connected together Internet is a mesh network Advantage Data will always be delivered Disadvantages Lots of cable Hard to setup 9A-18 Network Media Links that connect nodes in a network Choice can be made depending upon the following factors: Speed of transmission Size of network Security Can be broadly categorized as: Wire-Based Media Wireless Media 9A-19 Wire Based Media 1. Twisted-pair cabling Most common LAN cable Called Cat5 or 100BaseT Four pairs of copper cable twisted May be shielded from interference Speeds range from 1 Mbps to 1,000 Mbps 9A-20 Wire Based Media Coaxial cable 2. Fiber-optic cable 3. 9A-21 Similar to cable TV wire One wire runs through cable Shielded from interference Speeds up to 10 Mbps Nearly obsolete Data is transmitted with light pulses Glass strand instead of cable Immune to interference Very secure Speeds up to 100 Gbps Wireless Media Data transmitted through the air LANs use radio waves WANs use microwave signals Easy to setup Difficult to secure 9A-22 Network Hardware Network interface cards Network adapter Connects node to the media Unique Machine Access Code (MAC) Network linking devices Connect nodes in the network Cable runs from node to device Crossover cable connects two computers 9A-23 Network Hardware Hubs Center of a star network All nodes receive transmitted packets Slow and insecure Switches Replacement for hubs Only intended node receives transmission Fast and secure 9A-24 Network Hardware Bridge Connects two or more LANs together Packets sent to remote LAN cross Other packets do not cross Segments the network on MAC addresses Router Connects two or more LANs together Packets sent to remote LAN cross Network is segmented by IP address Connect internal networks to the Internet Need configured before installation 9A-25 Network Hardware Gateway Connects two dissimilar networks Most gateways contained in other devices 9A-26 Network Cabling Cabling specifications Bandwidth measures cable speed Typically measured in Mbps Maximum cable length Connector describes the type of plug 9A-27 Network Cabling Ethernet Very popular cabling technology 10 Base T, 10Base2, 10Base5 Maximum bandwidth 10 Mbps Maximum distances100 to 500 meters 9A-28 Network Cabling Fast Ethernet Newer version of Ethernet Bandwidth is 100 Mbps Uses Cat5 or greater cable Sometimes called 100Base T Requires a switch 9A-29 Network Cabling Gigabit Ethernet High bandwidth version of Ethernet 1 to 10 Gbps Cat 5 or fiber optic cable Video applications 9A-30 Network Cabling Token ring Uses shielded twisted pair cabling Bandwidth between 10 and 25 Mbps Uses a multiple access unit (MAU) Popular in manufacturing and finance 9A-31 Network Protocols Language of the network Rules of communication Error resolution Defines collision and collision recovery Size of packet Naming rules for computers 9A-32 Network Protocols TCP/IP Transmission Control Protocol/Internet Protocol Most popular protocol Machines assigned a name of 4 numbers IP address 209.8.166.179 is the White House’s web site Dynamic Host Configuration Protocol Simplifies assignment of IP addresses Required for Internet access 9A-33 Network Protocols IPX/SPX Internet Packet Exchange/Sequenced Packet Exchange Older protocol Associated with Novell Netware Replaced by TCP/IP 9A-34 Network Protocols NetBEUI Network BIOS Extended User Interface Used by Windows to name computers Transmission details handled by TCP/IP 9A-35 Network Protocols Token ring Popular in manufacturing and finance Nodes communicate when they have the token 9A-36 Modem Communications Plain Old Telephone System (POTS) Standard phone line Also known as Public Switched Telephone Network (PSTN) Two-way voice communication Uses analog transmission techniques Data communication is slow 9A-37 Modem Communications Modems Modulator/Demodulator Modulator converts digital to analog Speed measured in bits per second (bps) Current fastest speed is 56 Kbps Quality of phone lines dictates speed V.92 is the current modem standard Several modem types Internal External Voice Fax 9A-38 Modem Communications Modem uses Connection to the Internet File transfer Uploading Downloading 9A-39 Digital Data Connections Digital phone lines Local telephone companies are upgrading Service will faster and more reliable New phones will be needed Modems will need to be upgraded 9A-40 Digital Data Connections Broadband connection Any data connection faster than 56 Kbps Common in business Becoming popular in home installations 9A-41 Digital Data Connections ISDN lines Integrated Services Digital Network Basic rate uses three channels Two data channels each support 64 Kbps Error correction channel Primary rate uses 24 data channels 9A-42 ISDN Connection 9A-43 Digital Data Connections T lines High-capacity voice/data lines Used to control phone and data Several variants T1 transmits at 1.544 Mbps T3 transmits at 44.736 Mbps 9A-44 Digital Data Connections DSL technologies Digital Subscriber Line Popular with home users Speeds range from 100 Kbps to 30 Mbps Asymmetrical DSL (ADSL) Upload speed slower than download speed Symmetrical DSL (SDSL) Requires a DSL modem 9A-45 Digital Data Connections Cable modem connections Popular with home and office users Speeds between 1 and 3 Mbps Requires a cable modem 9A-46 Digital Data Connections ATM Asynchronous Transfer Mode Efficient transfer of video and sound Requires a special NIC and hardware 9A-47 Wireless Networks Benefits No cable to pull Mobile devices access network resources Mobility and flexibility for office workers 9A-48 Wireless Networks Wireless 802.11 Also called Wi-Fi IEEE standard Institute of Electronic and Electrical Engineers Several versions 802.11b connects up to 11Mbps 802.11g connects up to 56Mbps Use the same type of devices 9A-49 Wireless Networks Wireless Access Point Center of a wireless network WAP combined cover a larger area Range is 50 to 150 meters Extension points can extend range 9A-50 Wireless Networks Wireless Adapters Used by devices to connect Includes signal strength software 9A-51 Project Abstract Submission (next week) 9A-52 Chapter 9 End of Chapter