Traditionally Internet dominated by info retrieval applications
- typically using text and image transfer
- eg. email, file transfer, web
See increasing growth in multimedia applications
- involving massive amounts of data
- such as streaming audio and video
The Internet, until recently, has been dominated by information retrieval applications, e-mail, and file transfer, plus Web interfaces that emphasized text and images. Increasingly, the Internet is being used for multimedia applications that involve massive amounts of data for visualization and support of real-time interactivity. Streaming audio and video are perhaps the best known of such applications.
Although traditionally the term multimedia has connoted the simultaneous use of multiple media types (e.g., video annotation of a text document), the term has also come to refer to applications that require real-time processing or communication of video or audio alone. Thus, voice over IP (VoIP), streaming audio, and streaming video are considered multimedia applications even though each involves a single media type.
Elastic and Inelastic Traffic
elastic traffic
- can adjust to delay & throughput changes over a wide range
- eg. traditional “data” style TCP/IP traffic
- some applications more sensitive though
Inelastic traffic
- does not adapt to such changes
- eg. “real-time” voice & video traffic
- need minimum requirements on net arch
Traffic on a network or internet can be divided into two broad categories: elastic and inelastic. Elastic traffic can adjust, over wide ranges, to changes in delay and throughput across an internet and still meet the needs of its applications. This is the traditional type of traffic supported on TCP/IP-based internets and is the type of traffic for which internets were designed. Elastic applications include common Internet-based applications, such as file transfer, electronic mail, remote logon, network management, and Web access. But there are differences among the requirements of these applications.
Inelastic traffic does not easily adapt, if at all, to changes in delay and throughput across an internet. The prime example is real-time traffic, such as voice and video. The requirements for inelastic traffic may include the following: minimum throughput may be required, may be delay-sensitive, may require a reasonable upper bound on delay variation, may vary in the amount of packet loss, if any, that they can sustain.
These requirements are difficult to meet in an environment with variable queuing delays and congestion losses. Accordingly, inelastic traffic introduces two new requirements into the internet architecture.
Multimedia Technologies
Stallings DCC8e Figure 2.11 looks at multimedia from the perspective of three different dimensions: type of media, applications, and the technology required to support the applications. Consider the list of technologies relevant to the support of multimedia applications. As can be seen, a wide range is involved. The lowest four items on the list are beyond the scope of this book. The other items represent only a partial list of communications and networking technologies for multimedia. These technologies and others are explored throughout the book.
Summary
- introduced need for protocol architecture
- TCP/IP protocol architecture
- OSI Model & protocol architecture standardization
- Traditional vs Multimedia Applications