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TCP (Transfer Control Protocol) focuses on software, assuring that the data actually 

ALPHABET SOUP:

gets sent, is delivered, and is correctly reassembled at the other end. If any errors occur 

A PROTOCOL PRIMER

during transport, such as degradation or loss of some packets, TCP will call for those 

packets to be resent. TCP also works to optimize network bandwidth by dynamically 

FTP (File Transfer Protocol)

controlling the fl ow of information, slowing it down as the network becomes congested. 

  Uses TCP/IP (one to one, reliable)

  Transfers fi les across the Internet

HTTP (HyperText Transfer Protocol) is the protocol used to transfer hypertext fi les on 

  Typically used to transfer Web pages 

the Web. Hypertext, invented by Ted Nelson in the 1960s, is the standard for content 

from the computer on which they 

on the Web i.e., Web pages are hypertext fi les. Hypertext is a database system by 

were created, to the server from 

which they will be hosted 

which related  objects  (text, pictures, music, video, etc.) can all be linked together, 

offering a non linear experience of the information. In general usage, hypertext has 

IP (Internet Protocol)

come to refer to any text that contains  links  to other documents. Since hypertext 

  Underlying protocol which transmits 

data across the Internet

is interactive, it requires a two way communication protocol that allows the receiver 

  Supports real time transfer of data 

to communicate back through the network, to call up the URLs for the objects to 

which the hypertext is linked. Take care not to confuse HTTP a protocol with 

HT TP (Hypertext Transfer Protocol)

HTML (HyperText Markup Language), which is the computer language typically used 

  Uses TCP/IP (one to one, reliable)

to code Web pages, defi ning how they look and how they behave.

  Protocol for transmitting hypertext 

fi les, typically used for transmitting 

FTP (File Transfer Protocol) is an effi cient protocol used for transferring fi les between 

Web pages

two devices over the Internet, and does not rely on the Web. FTP is used for a wide 

RTP (Real time Transfer Protocol)

variety of purposes, as it is handy for the upload or download of most any type of 

  Layered on top of IP or UDP which 

fi le. FTP is typically used for transferring Web pages from the computer on which they 

support real time transfer of data

were created to the server that will host the site of which they will be a part.

   No error handling, no reliability, no 

real time guarantee

HTTP and FTP cannot be used for true streaming

  Information is time stamped for 

synchronization

HTTP and FTP are both layered on top of TCP, a protocol that ensures the retrans 

  One to one or one to many

mission of lost or damaged packets. Audio and video content transmitted using these 

protocols will be received intact eventually. Lost or damaged packets are simply 

RTSP (Real Time Streaming Protocol)

  Protocol for handling streaming 

resent. This works just fi ne for the traditional  download it and then play it  modality, 

media, which supports VCR like 

where the fi le will not be played back until it is received in its entirety. 

operations

When HTTP is used for progressive download, the very reliability of the protocol can 

  Uses TCP; layered on top of RTP

cause problems, as the retransmission of lost or damaged packets may disrupt pseudo 

SMTP (Simple Mail Transfer Protocol)

streaming playback. The media fi le will still eventually arrive in its entirety, can be 

  Protocol for handling e mail

saved, and can then be smoothly played back from the destination hard drive, just 

  E mail client software uses the SMTP 

as it could be with a traditional download. So, as reliable as they are for document 

protocol to send mail to an e mail 

server and POP3 or IMAP4 protocols to 

transmission, HTTP and FTP cannot be used for true streaming, because their error 

fetch mail from an e mail server. 

correction schemes undermine the temporal relationship between video and audio 

packets. They provide no facility for  accommodating the data transfer rate to the audio 

TCP (Transfer Control Protocol)

or video data rate that is, the rate at which the data comprising the media plays back. 

  Layered on top of IP

Using HTTP or FTP, a one minute movie might download in one second, one minute, 

  Establishes a virtual connection 

between a destination and a source

or even take an hour, depending on the size of the fi le and the speed of the connection. 

  Handles congestion and reliability

If the connection speed is less than the media's data rate, the media still makes it to the 

  One to one

client, progressive download just won't play smoothly. 

TCP/IP

  Protocol suite comprised of IP, TCP, 

RTP enables streaming 

and some other protocols

RTP (Real time Transfer Protocol) transmits data in real time. This means that a one  

  The protocol which handles most 

minute movie is transmitted in one minute. Layered on top of UDP (User Datagram 

Internet traffi c

Protocol), rather than on top of TCP, RTP provides very little error correction; lost, 

namic Medianamic Media

UDP (User Datagram Protocol)

late, or damaged packets are simply dropped. Whatever data arrives is what plays. So, 

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  Layered on top of IP

when we say that streaming is a  forgiving  medium, we are referring to the fact that it 

  Unlike TCP, no virtual connection

will keep on playing, even if it  skips a beat,  and that these losses are tolerable even 

  Provides very little error recovery

preferable, to the delays that would be imposed using TCP. In fact,  Live Live  streaming 

  One to many

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would be impossible without this tolerance. Of course, if the connection speed is lower 

  Used primarily for broadcasting 

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than the data rate, playback will be  jerky,  or the media might not play at all. 

information over the Internet

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