Networking Protocol

Networking Protocol Exchanging packets and data and communicating with computers

Contents • Ethernet • LocalTalk • Token Ring • FDDI • ATM • TCP/IP • UDP • Example Usage of Protocols

Ethernet • The Ethernet protocol is one that is the most widely used.

Ethernet • The Ethernet protocol is one that is the most widely used. • Using a CSMA/CD method, each computer listens to the line to see if it is clear, if it is clear then it sends information, if not it waits until the line is clear to send information.

But WAIT!

What happens when TWO computers try to transmit information at the same time???

Carrier Sense Multiple Access/Collision Detection • When this happens a collision occurs. Each computer then backs off and waits a random amount of time before attempting to retransmit the information. • Station A wishes to send a frame. First, it checks if the medium is available (Carrier Sense). If it isn't, it waits until the current sender on the medium has finished. • Suppose Station A believes the medium is available and attempts to send a frame. Because the medium is shared (Multiple Access), other senders might also attempt to send at the same time. At this point, Station B tries to send a frame at the same time as Station A. • Shortly after, Station A and Station B realize that there is another device attempting to send a frame (Collision Detect). Each station waits for a random amount of time before sending again. The time after the collision is divided into time slots; Station A and Station B each pick a random slot for attempting a retransmission. • Should Station A and Station B attempt to retransmit in the same slot, they extend the number of slots. Each station then picks a new slot, thereby decreasing the probability of retransmitting in the same slot.

FDDI’s

What is FDDI FDDI stands for Fiber Distributed Data Interface. FDDI Is a 100 Mbps fiber optic LAN. It uses counter- rotated ring topology FDDI is usually considered the backbone of any LAN network.

Counter Rotated? The use of a ring topology in such a manner the renders your network very efficient. Each node is physically connected with the others . There is one cable going one way and one going the other way. This ensures that even if one node fails, the network still works

Counter rotated

ATM ATM stands for Asynchronous Transfer Mode Transfers at a rate of 155 to 2488 Mbps Information for multiple service types such as video, data, or voice can be transferred Information is transferred in small packet sizes Combines benefits of circuit switching and packet switching. An ATM packet has a header and a payload The ATM network consists of switches and endpoints

Example of ATM NEtwork NOTE**** Public ATM systems link different private systems together This entire system is extremely fast and efficient However it is very complex technology and is rather expensive It is becoming more and more cost effective over time

LOCAL TALK & TOKEN RING • LocalTalk • Developed by Apple Computer, Inc. for Macintosh computers. - LocalTalk is called CSMA/CA Access with Collision Avoidance). It is similar to CSMA/CD except that the computer signals its intent to transmit before it actually does so. • - The Macintosh operating system allows the establishment of a peer-to-peer network without the need for additional software.

Token Ring • Was developed by IBM in the mid-1980s. The access method • - In Token Ring, the computers are connected so that the signal travels around the network from one computer to another in a logical ring. • - A single electronic token moves around the ring from one computer to the next. If a computer does not have information to transmit, it simply passes the token on to the next workstation. • - The token then proceeds around the ring until it comes to the computer for which the data is meant.

A Visual Explanation.. A Clay Animation About Computer Networking: http://www.youtube.com/watch?v=yGJGIUa-xWE

Computers use mainly two forms of communication, TCP/IP and UDP. Both are used to send and receive information, however they are distinctly different. Both forms of communication are used for different situations, however TCP/IP is the most commonly used. Communication Protocols

Computers use standardized protocols so any computer can communicate with another If there were different communication methods, computers could not properly communicate with each other Mr. Henrich compares this situation to how Canada’s railroads weren’t the same size as American railroads Why are there only a few Protocols?

TCP/IP plays a huge role in the computer world. IP protocol deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they were sent. To use TCP/IP, you must first open the connection between the two end points. Both ends know when the session is opened (begin) and is closed (end). The data transfer cannot take place before both ends have agreed upon the connection. The connection can be closed by either side; the other is notified. Transmission Control Protocol

TCP/IP is a more formal way of communication, both ends must “shake hands” before a connection and stream is made. It is the most reliable and stable connection protocol there is. An example situation of TCP/IP in action is browsing the internet To see example HTTP headers: http://www.http.header.free.fr/http.html Transmission Control Protocol (Cont.)

Using UDP, programs on networked computers can send short messages sometimes known as datagrams (using Datagram Sockets) to one another. UDP is described as a “connectionless” form of communication, where instead of the handshake and stream of data in TCP, UDP broadcasts the data. UDP is used mainly for massive amounts of data that needs to be sent and delivered. A known program used by several people today that uses UDP is Limewire, where users send and receive massive amounts of data (I download at roughly 230KB/S) User Datagram Protocol

TCP is a connection-oriented protocol, which means that upon communication it requires handshaking to set up end-to-end connection. Reliable - TCP manages message acknowledgment, retransmission and timeout. If data gets lost along the way, the server will re-request the lost part. In TCP, there's either no missing data. Ordered - if two messages are sent along a connection, one after the other, the first message will reach the receiving application first. When data packets arrive in the wrong order, the TCP layer holds the later data until the earlier data can be rearranged and delivered to the application. Heavyweight - TCP requires three packets just to set up a socket, before any actual data can be sent. It handles connections, reliability and congestion control. It is a large transport protocol designed on top of IP. Streaming - Data is read as a "stream," with nothing distinguishing where one packet ends and another begins. Packets may be split or merged into bigger or smaller data streams arbitrarily. **Important for transfering large amount of data* UDP is a simpler message-based connectionless protocol. In connectionless protocols, there is no effort made to setup a dedicated end-to-end connection. Communication is achieved by transmitting information in one direction, from source to destination without checking to see if the destination is still there, or if it is prepared to receive the information. With UDP messages (packets) cross the network in independent units. Unreliable - When a message is sent, it cannot be known if it will reach its destination; it could get lost along the way. There is no concept of acknowledgment, retransmission and timeout. Not ordered - If two messages are sent to the same recipient, the order in which they arrive cannot be predicted. Lightweight - There is no ordering of messages, no tracking connections, etc. It is a small transport layer designed on top of IP. **Speed** Comparing UDP to TCP/IP

File Transfer Protocol (FTP) is a network protocol used to transfer data from one computer to another through a network such as the Internet. FTP is a file transfer protocol for exchanging and manipulating files over a TCP computer network. A FTP client may connect to a FTP server to manipulate files on that server. Example of TCP/IP Usage

This diagram is how MSN communication works (an educated guess). Example usage of the protocols • Reminder: see Turing example

In conclusion, it is clear that computers would not be as useful if it weren’t for Protocols to communicate between computers. It set of rules that governs the communications between computers on a network Thanks you  Conclusion

Networking Protocol