understanding+the+basic+of+ …hardware+ • fileservers • workstaons+ • network+interface+card+...
TRANSCRIPT
Understanding the Basic of Computer Network:
Networking Hardware and Network Opera;ng System
Heng Sovannarith [email protected]
Networking Hardware
• 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 hub hub
hub
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.)
A
B C
D E
F G
H
Bridge
Segment A Segment BA Transmits to C, bridge will not pass it to Segment B
G Transmits to B, bridge will pass it to Segment A
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