ComputerNetworks (2).ppt

Network Basics Network Definition  Set of technologies that connects computers  Allows communication and collaboration between users 9A-2 The Uses of a Network  Simultaneous access to data  Data files are shared Access can...

Network Basics Network Definition  Set of technologies that connects computers  Allows communication and collaboration between users 9A-2 The Uses of a Network  Simultaneous access to data  Data files are shared Access can be limited  Shared files stored on a server  Software can be shared Site licenses Network versions Application servers 9A-3 The Uses of a Network  Shared peripheral device  Printers and faxes are common shares  Reduces the cost per user  Devices can be connected to the network  Print servers control network printing Manage the print queue 9A-4 Sharing Data File server contains documents used by other computers. 9A-5 The Uses of a Network  Personal communication  Email Instantaneous communication  Conferencing Tele conferencing Videoconferencing Audio-conferencing Data-conferencing  Voice over IP Phone communication over network wires 9A-6 Voice Over IP 9A-7 The Uses of a Network  Easier data backup  Backup copies data to removable media  Server data backed up in one step 9A-8 Common Network Types  Local Area Network (LAN)  Containsprinters, servers and computers  Systems are close to each other  Contained in one office or building  Organizations often have several LANS 9A-9 Common Network Types  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-10 Hybrid Network Types  Campus Area Networks (CAN) A LAN in one large geographic area  Resources related to the same organization  Each department shares the LAN 9A-11 Hybrid Network Types  Metropolitan Area Network (MAN)  Large network that connects different organizations  Shares regional resources A network provider sells time 9A-12 Hybrid Network Types  Home Area Network (HAN)  Small scale network  Connects computers and entertainment appliances  Found mainly in the home 9A-13 Hybrid Network Types  Personal Area Network (PAN)  Very small scale network  Range is less than 2 meters  Cell phones, PDAs, MP3 players 9A-14 How Networks Are Structured ?  Server based network  Node is any network device  Serverscontrol what the node accesses  Users gain access by logging in  Server is the most important computer 9A-15 How Networks Are Structured  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  Server is the most important computer 9A-16 How Networks Are Structured  Peer to peer networks (P2PN)  All nodes are equal  Nodes access resources on other nodes  Each node controls its own resources  Distributing computing is a form 9A-17 Network Topologies  Topology  Logical layout of wires and equipment  Choice affects Network performance Network size Network collision detection  Several different types 9A-18 Network Topologies  Packets  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 9A-19 Network Topologies  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-20 Network Topologies  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-21 Star Topology 9A-22 Network Topologies  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-23 Network Topologies  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-24 Mesh Topology 9A-25 Network Media  Links that connect nodes  Choice impacts  Speed  Security  Size 9A-26 Wire Based Media  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-27 Wire Based Media  Coaxial cable  Similar to cable TV wire  One wire runs through cable  Shielded from interference  Speeds up to 10 Mbps  Nearly obsolete 9A-28 Wire Based Media  Fiber-optic cable  Data is transmitted with light pulses  Glass strand instead of cable  Immune to interference  Very secure  Hard to work with  Speeds up to 100 Gbps 9A-29 Wireless Media  Data transmitted through the air  LANs use radio waves  WANs use microwave signals  Easy to setup  Difficult to secure 9A-30 Network Hardware  Network interface cards  Network adapter  Connects node to the media  Unique Machine Access Code (MAC) 9A-31 Network Hardware  Network linking devices  Connect nodes in the network  Cable runs from node to device  Crossovercable connects two computers 9A-32 Network Hardware  Hubs  Center of a star network  Allnodes receive transmitted packets  Slow and insecure 9A-33 Network Hardware  Switches  Replacement for hubs  Only intended node receives transmission  Fast and secure 9A-34 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 9A-35 Network Hardware  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-36 Network Hardware  Gateway  Connects two dissimilar networks  Connects coax to twisted pair  Most gateways contained in other devices 9A-37 Network Cabling  Cabling specifications  Bandwidth measures cable speed Typically measured in Mbps  Maximum cable length  Connector describes the type of plug 9A-38 Network Cabling  Ethernet  Very popular cabling technology  10 Base T, 10Base2, 10Base5  Maximum bandwidth 10 Mbps  Maximum distances100 to 500 meters 9A-39 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-40 Network Cabling  Gigabit Ethernet  High bandwidth version of Ethernet 1 to 10 Gbps  Cat 5 or fiber optic cable  Video applications 9A-41 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-42 Network Protocols  Language of the network  Rules of communication  Error resolution  Defines collision and collision recovery  Size of packet  Naming rules for computers 9A-43 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-44 Network Protocols  IPX/SPX  Internet Packet Exchange/Sequenced Packet Exchange  Older protocol  Associated with Novell Netware  Replaced by TCP/IP 9A-45 Network Protocols  NetBEUI  Network BIOS Extended User Interface  Usedby Windows to name computers  Transmission details handled by TCP/IP 9A-46 Network Protocols  Token ring  Popular in manufacturing and finance  Nodes communicate when they have the token 9A-47 Reference McGraw-Hill Technology Education Copyright © 2006 by The McGraw-Hill Companies, Inc. 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