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Network communications devices Hardware – Modems

Network communications devices Hardware – Modems. Short for mo dulator- dem odulator. A modem is a device to transmit data over telephone or cable lines.

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Network communications devices Hardware – Modems

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  1. Network communications devices Hardware – Modems • Short for modulator-demodulator. A modem is a device to transmit data over telephone or cable lines. • Computer information is stored digitally whereas information transmitted over telephone lines is transmitted in the form of analog waves. A modem converts • between these two forms. • Maximum 56k • Very slow ADSL Modem

  2. Hardware – Modems, ADSL • Asymmetric digital subscriber line (ADSL); asymmetric b/c more bandwidth is reserved for receiving data than sending, download speeds from 256 kbps to 8 mbps; upload speeds, 16 to 640 kbps • Faster data transfer rates, up to 1500kbps, broadband • Simultaneously talk on phone, send fax • Always on • Cost effective; no dropped connections, faster downloads, no busy signals • Major problem is distance from station, 5 km max. • Security issues, need firewall software

  3. Hardware - NIC • The Network interface card (NIC) allows a stand-alone computer to connect to a network. These can be cabled, or wireless (radio) cards. • WAP connects wireless communication devices to a wired or wireless network • NICs are rated by speed: 10, 100, or ‘Gigabit’ 1000Mbps. • For a NIC to work at its maximum speed, all the other network devices between it and the server must have the same – or greater – bandwidth (data-carrying capacity).

  4. Hardware – Wireless access point • Device that allows computers and devices to transmit data wirelessly among themselves. • WAPs installed on a LAN behind the firewall

  5. Hardware –Switches switches are devices that provide connection point for nodes on a network. Switch stores the address of every device down each cable connected to it.

  6. Hardware –Switches Switches (“switching hubs”) are clever enough to only pass on relevant network traffic. Switches greatly reduce network congestion, various sizes, 24, 48 port

  7. Hardware – Routers • Security device that guards the connection between a LAN and the outside world (another LAN or a WAN.) A junction between 2 networks; connects multiple networks • Can be programmed to only allow authorised incoming and outgoing traffic. E.g. it can block certain external sites or forbid MP3 music files to enter. Like an enthusiastic bouncer at the door of a club. • Routers can protect one part of a network from another part of the same network, e.g. school admin LAN and curriculum LAN.

  8. Hardware – Routers

  9. Communications software • FTP • Communication software programs that support file transfer protocol • An internet standard that allows you to upload and download files to and from a web server, ftp server.

  10. Communications software -FTP

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