What is Networking?

Various levels of knowledge exist when discussing what makes up the internet, how data transfers from host to host, and what are the ‘rules’ or protocols which make it all possible. For most of us a wire with a connector which looks similar to a phone cord plugs into your computer and the other end into a modem, router, switch or device which connects you to your T-1, DSL, or Broadband connection.

IP addresses are globally unique, 32 bit numbers assigned first by a Regional Internet Registry (RIR) such as ARINN (arin.net) to large facility based ISP’s, then individually to end users. The IP address is a four byte value that (by convention) is expressed by converting each byte into a decimal number (0 to 255) and separating the bytes by a period. "Class C" network are smaller networks, in which the first three bytes identify the network and the last byte identifies the individual computer. Larger organizations can get a "Class B" network where the first two bytes only identify the network and the last two bytes identify the individual workstations (up to 64 thousand). Ethernet Devices over TCP/IP: Ethernet controller comes with an address built-in from the factory. In order to make sure that they would never have to reuse addresses, the Ethernet designers allocated 48 bits for the Ethernet address. There is no connection between the Ethernet address and the Internet address. Each machine has to have a table of what Ethernet address corresponds to what Internet address.

When data packets are received by the other end, all the headers are removed. IP removes the IP header. Since the protocol type is TCP, it passes the datagram to TCP. TCP looks at the sequence number. It uses the sequence numbers and other information to combine all the datagrams back into the original file.