Download Understanding the Basic of Computer Network

Understanding the Basic of Computer Network: Networking Hardware and Network Opera;ng System Heng Sovannarith [email protected] Networking Hardware • 
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File Servers Worksta;ons Network Interface Card Repeaters Hub Switch Bridges Router Introduc;on •  Networking hardware includes all computers, peripherals, interface cards and other equipment needed to perform data-­‐
processing and communica;ons within the network. File/Network Server •  One or more network servers is a part of nearly every local area network. •  These are very fast computers with a large amount of RAM and storage space, along with a one or more fast network interface card(s). •  The network opera;ng system provides tools to share server resources and informa;on with network users. File/Network Server (cont.) •  A sophis;cated permissions-­‐handling system is included, so that access to sensi;ve informa;on can be carefully tailored to the needs of the users. •  For small networks, a singe network server may provide access control, file sharing, printer sharing, email, database, and other services. File/Network Server Worksta;ons •  Computers that humans use are broadly categorized as worksta;ons. •  A typical worksta;on is a computer that is configured with a network interface card, networking soSware, and the appropriate cables. •  Worksta;ons do not necessarily need large storage hard drives, because files can be saved on the file server. •  Almost any computer can serve as a network worksta;on. Network Interface Cards •  The network interface card (NIC) provides the physical connec;on between the network and the computer worksta;on. •  Network interface cards are a major factor in determining the speed and performance of a network. •  It is a good idea to use the fastest network card available for the type of worksta;on you are using. •  The most common network interface connec;ons are Ethernet cards and wireless adapters. Network Interface Cards (cont.) •  Ethernet card can be used with coaxial, twisted pair, or fiber op;cs cable. •  Wireless adapters are found in most portable devices, such as laptops, smart phones, and tablet devices. Network Interface Cards (cont.) Repeater •  Since a signal loses strength as it passes along a cable, it is oSen necessary to boost the signal with a device called a repeater. •  The repeater electrically amplifies the signal it receives and rebroadcasts it. •  They are used when the total length of your network cable exceeds the standards set for the type of cable being used. Repeater (cont.) •  Func;ons at the Physical Layer of the OSI model •  A mul;-­‐port repeater is known as a Hub •  Connects segments of the same network, even if they use different media • 
Repeater
Hub •  Allows the mul;ple connec;on of devices •  In reality a Hub is a Repeater with mul;ple ports •  Func;ons in a similar manner to a Repeater •  Works at the Physical Layer of the OSI model •  Hubs do not manage any of the traffic that comes through them. Any packet entering a port is broadcast out or "repeated" on every other port, except for the port of entry. Hub (cont.) hub
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Switch •  An switch is a device that provides a central connec;on point for cables from worksta;ons, servers, and peripherals. •  Modern switches build a port map of all IP address which respond on each port, and only broadcasts on all ports when it doesn't have a packet's target IP address already in its port map. •  An switch operates at Layer 2 (the data link layer) of the OSI model. •  Most large networks use switches rather than hubs to connect computers within the same subnet. Switch (cont.) Bridge •  A bridge is a device that connects a local area network (LAN) to another local area network that uses the same protocol (for example, Ethernet or Token Ring). •  It looks at the des;na;on of the packet before sending. If the des;na;on address is not on the other side of the bridge it will not transmit the data. •  A bridge only has one incoming and one outgoing port. •  Bridges are typically used to separate parts of a network that do not need to communicate regularly, but s;ll need to be connected. Bridge (cont.) Bridge
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Router •  A router is similar in a switch in that it forwards packets based on address. •  But, instead of the MAC address that a switch uses, a router can use the IP address. •  This allows the network to go across different protocols. •  A router is connected to two or more data lines from different networks. •  An Router operates at Layer 3 (the network layer) of the OSI model. Router (cont.) •  Work in LAN, MAN and WAN environments •  Can interconnect different networks – Ethernet with Token Ring •  Allows access to resources by selec;ng the best path •  Two primary func;ons – to determine the ‘best path’ and to share details of routes with other routers Router (cont.) •  Two primary func;ons – to determine the ‘best path’ and to share details of routes with other routers •  Rou;ng Table – a database which keeps track of the routes to networks and the associated costs Router (cont.) •  Sta;c Rou;ng – routes are manually configured by a network administrator •  Dynamic Rou;ng – adjust automa;cally to changes in network topology, and informa;on it receives from other routers •  Rou;ng Protocol – uses a special algorithm to route data across a network Firewall •  A firewall is a networking device that is installed at the entrance to a LAN when connec;ng a networks together, par;cularly when connec;ng a private network to a public network, such as the internet. •  Firewalls are either hardware or soSware, depending on their intended use. Network Opera;ng System •  Unlike opera;ng systems, such as Windows, that are designed for single users to control one computer, network opera;ng systems (NOS) coordinate the ac;vi;es of mul;ple computers across a network. •  The network opera;ng system acts as a director to keep the network running smoothly. •  The two major types of network opera;ng systems are: –  Peer to Peer –  Client/Server Peer-­‐to-­‐Peer •  Peer-­‐to-­‐peer network opera;ng systems allow users to share resources and files located on their computers and to access shared resources found on other computers. •  However, they do not have a file server or a centralized management source •  In a peer-­‐to-­‐peer network, all computers are considered equal; they all have the same abili;es to use the resources available on the network. Peer-­‐to-­‐Peer (cont.) •  Peer-­‐to-­‐peer networks are designed primarily for small to medium local area networks. •  Nearly all modern desktop opera;ng systems, such as Macintosh OSX, Linux, and Windows, can func;on as peer-­‐to-­‐peer network opera;ng systems. •  •  Peer-­‐to-­‐Peer (cont.) •  Advantages of a peer-­‐to-­‐peer network: –  Less ini;al expense -­‐ No need for a server. –  Setup -­‐ An opera;ng system (such as Windows XP) already in place may only need to be reconfigured for peer-­‐to-­‐peer opera;ons. •  Disadvantages of a peer-­‐to-­‐peer network: –  Decentralized -­‐ No central loca;on for files and applica;ons. –  Security -­‐ Does not provide the security available on a client/server network. Client/Server •  Client/server network opera;ng systems allow the network to centralize func;ons and applica;ons in one or more file servers •  The file servers become the heart of the system, providing access to resources and providing security. •  Individual worksta;ons (clients) have access to the resources available on the file servers. •  UNIX/Linux and the MicrosoS family of Windows Servers are examples of client/server network opera;ng systems. Client/Server (cont.) Client/Server (cont.) •  Advantages of a client/server network: –  Centralized -­‐ Resources and data security are controlled through the server. –  Scalability -­‐ Any or all elements can be replaced individually as needs increase. –  Flexibility -­‐ New technology can be easily integrated into system. –  Interoperability -­‐ All components (client/network/
server) work together. –  Accessibility -­‐ Server can be accessed remotely and across mul;ple plaeorms Client/Server (cont.) •  Disadvantages of a client/server network: –  Expense -­‐ Requires ini;al investment in dedicated server. –  Maintenance -­‐ Large networks will require a staff to ensure efficient opera;on. –  Dependence -­‐ When server goes down, opera;ons will cease across the network. Network Opera;ng System SoSware •  some of the more popular peer-­‐to-­‐peer and client/server network opera;ng systems: – Macintosh OS X – MicrosoS Windows Server – UNIX/Linux