NETWORK & INTERNET
To become part of a network, a PC uses a network interface (NIC) communicate signals pass from the PC’s RAM thru NIC to a LAN’s backbone. The NIC data can be sent along by cable or by wireless adaptor to the network. The most common network is Ethernet, which sends data from one node to another in packets format.
Packet format comes with Preamble, Destination Address, Source Address, Type, Data and CRC bits.
For a data or file travel thru a network, it must pass thru following layers to ensure the data gets throught intact and accurte
- Application layer converts a messages’s data nto bits and attaches a header to ID the sending and receiving computer
- Presentation layer translates data/file into ASCII code, compresses and encrypts the data as needed.
- Session layer set boundaries for beginning and end of the message and determine is half or full duplex.
- Transport layer protect the data and subdivides the data into segments and creates checksum test.
- Network layer selects a route for the message and forms segment into packets, count them and add header with address info.
- Data-link layer supervise the transmission. Keep a copy of each packet until it receive confirmation from next point.
- Physical layer encodes the packet into medium that will carry them (from digital to analog signal).
A net work uses hubs, switches and routers to move data to the right destination and to ward off intruders from the internet.
- Hubs – A hub receives incoming data packets from different nodes and places them into the memory buffer temporary if hub is busy with another packet.
- Switches – switch function is similar to hub but knows which of its connections lead to specific nodes.
- Routers - router function is similar to switch except that a router only delivery data to the specific address.
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