Network Protocol

Home

What is a Network?

Wiring

Client-Server

Security

Terms/Definitions


Speaking the Language

In order for networks to communicate within themselves and with other networks, a certain protocol is to be followed. A standard language is needed to send information and receive information through the networks. Historically there have been several protocols that have come and gone, such as IBM's token-ring, its highly organized system of communication causing it to be very slow and expensive beyond the average user's desire to pay. Currently, the standard in LANs is ethernet technology, and for communicating across the Internet the standard is TCP/IP.

Ethernet

In a LAN, each PC with its unique NIC is linked with wiring to an ethernet hub or switch. When information is sent from one computer in the network, it is broadcast on a channel across all of the PCs in the same network, thus each PC can detect the signal. If the information does not apply to certain PCs in the network, then the NIC in those PCs automatically discards the information. Basically only one communcation can take place at a time over an ethernet because it is broadcast across the network. So after one communication is sent, then the next communication that is sent the fastest after the first will be processed and sent, and then the next, and so forth and so on. Snyder compares the process to the protocol for speaking at a party. One person is telling a story to the people at the party, and they are all listening. Then, when that person is done telling his story, there is perhaps a pause, and another person chimes in with his story. If two people begin at once, then the one that started first is given the go-ahead, and the other person waits until that story is done, then he begins telling his story. Of course, on the ethernet, all of this information can be be sent and received very quickly with little pauses or delays since the traffic is not extremely high on any given ethernet.

The whole process has also been compared to the process of entering, driving on, and exiting a highway. If traffic is high, then it is will likely be harder to get on and will take a little more time to get to the intended exit and destination. Sometimes there will be crashes, and the process is repeated. When the traffic is low, the information is sent quickly and arrives quickly. Each chunk of information is travelling on this highway and is then reassembled into the whole message/file in each receivers' NIC.

Advantages of a Switch

A switch helps reduce the traffic in a network better than a hub. As has been already mentioned, a hub lets through all the traffic on all ports, sending all data to everyone in the network, creating a lot of traffic. A switch, however, doesn't send information to everyone. It only sends information through one port to those communicating, thus making the network highway more efficient.

TCP/IP

The Internet uses the Transmission Control Protocol/Internet Protocol process for sending and receiving information. This process has been compared by Vincent Cerf to sending the content of an entire novel on postcards from Tahiti to New York City. First, the novel is broken up into units of a few sentences on each postcard, each postcard marked with a unique number as to where it fits into the entire sequence, and also bearing the destination address, the publisher in New York. When put in the mailbox, the postal service then sorts them out and puts them on different planes to get to NY, some going east and some going west. So different routes are taken but they all end up getting to NY and being reassembled by the publisher for the complete content. This is how the internet works. Each computer has a unique IP (Internet Protocol) address assigned by the Internet service provider. The sender's message is broken up into individual IP packets, each labeled with the sender's IP address and the destination IP address and marked with its sequence number in the overall message. As each packet arrives at its destination, it is reassembled in sequential order on the server or PC for the receiving user to view.



Home

What is a Network?

Wiring

Client-Server

Security

Terms/Definitions


Last Updated 3/29/04
Dustin Wilder
Student, University at Albany 1