Network Devices

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** Computer Networking computer network :

 connectivity between group of devices(Nodes) that use a set of common communication protocols over digital interconnections (Network Media) for the purpose of sharing resources.

 A communication protocol is a set of rules for exchanging information over a network.

** The interconnections (Network Media) between devices may be

 Wired (copper cable)

 Optical (Glass cable)

 Wireless(Wi-Fi)

** devices of a computer network :

* End devices such as personal computers(PC)and servers.

          - end device is originates message or received message.

          - Every computer on a network is called a host or end device.

          - Servers are computers that provide information to end devices-  

* Intermediary devices such as switches, routers and firewall.

            - An intermediary device interconnects end devices together.

1 - Network interface Card (NIC)

 A NIC is a printed circuit board on a computer motherboard and sometimes called network adapters.

 NIC is used to physically connect host devices to the network media.

 Each NIC is identified by a unique code called a Media Access Control (MAC) address.

 This address is used to control data communication for the host on the
network.

2- Repeater

* A repeater is a network device used to regenerate a signal.

* Repeaters regenerate analog or digital signals that are distorted by transmission loss due to attenuation.

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3- HUB

 Hub connect between group of hosts and allow the network to see them as a single unit in Local Area Network (LAN).

 transfer data for all devices connected to hub. 

Passive hub : connect between group of hosts without any other effect on the data transmission.

  Active hubs : connect between group of hosts and also regenerate signals.

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4- Switch

 Switch connect between group of hosts and allow the network to see them as a single unit in Local

Area Network (LAN) .

 Switches more intelligence to data transfer management and transfer data only to the connection that needs it.

 switch does not convert data transmission formats.

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5- Bridge

 Bridges connections between LANs and can regenerate the signal.

 Bridges convert network data transmission formats .

 check data to determine if it should cross the bridge and transfer data only to the connection that needs it.

6- Router

 Routers can regenerate signals.

 Routers convert data formats and manage data transfers.

 They can also connect to a WAN, which allows them to connect LANs that are separated by great distances.

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7-gateway

 Gateway is a network device used in telecommunications that connects two networks with different transmission protocols together.

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8- Firewall

 A firewall is a network device or software for controlling network security and access rules.

 Firewalls are inserted in connections between secure internal networks and insecure external networks such as the Internet.

 Firewalls are configured to reject access requests from unrecognized

sources while allowing actions from recognized ones.


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