Marian Elam

Summer 1998

It seems hardly reckless to state that every minute on the Internet, information overload on overextended networks causes frustration and lost opportunities. Numerous approaches to the underlying problems of poor network performance have been and are in the works. In recent years, a variety of data transmission techniques have evolved communications technology from general broadcasts (point to mass) to unicasts (point to point; e.g. push technology).

While push technology is timely and current, the next wave of transmission technology is presumably already making waves: multicasting is the next step in the logical progression of data transmission technology. This report will briefly define these technologies and comment on their utility.

Statistical measures of network traffic are network throughput and peak time usage. Network throughput is a measure of the relative efficiency of aggregate transmission performance (i.e., concurrent and/or cumulative Internet speed "bottlenecks" (e.g. PC performance, modem speed, bandwidth, source and destination Internet Server Provider (ISP) loading); ("Real-Life Throughput Browser Tuner 98," 1998). Peak time usage refers to the average relative availability of shared network resources (i.e., Internet loading at a given point of time). These measures of Internet performance have been used to attribute improvements in Internet loading to the aforementioned transmission technologies.

Proposed solutions to information overload on the Internet include both unicast applications such as push (technology) and multicasting.

To be technical, there are different methods of broadcasting on the Internet, the latest form being multicasting. The evolution of multicasting starts with unicasting, where one sends and another receives, and a separate data stream is needed for each recipient. In a situation of broadcasting (one-to-all), there is one sender with everyone on the network receiving. And multicasting occurs when one person sends and anyone who wants to can receive by signing up (Berst, May 19, 1997). A discussion of push technology, an application of unicasting, and multicasting is provided.

Push media is the automatic delivery of applications and information to users without their having to surf the World Wide Web (Thomas). A claimed solution to information overload, users may select the channels of information they wish to receive.

"Channels are information-oriented web sites that use webcasting software to bring focused, up-to-date content to the user's desktop," delivering dynamic information, which is transparently downloaded in the background, so that it is instantly available, online or off (Netcaster's Developer's Guide). At home or in the computer lab, a user often will be required to have only a minimum skill level with internet applications to begin work when signing on to the Internet and a specific channel. Users can publish their work on channels with little or no programming. A web site does not have to have content created specifically for push publishing in order for a push software application to receive its content created in HTML, Java, or Javascript (Goreman, 1997).

PointCast is the most popular push service, with more than one million users. It provides electronic news delivery. Users can create their own channels, thus furthering PointCast as a viable model for business usage ("Converting.").

Although PointCast has a web browser, it does not have to be constantly connected to the Internet to provide channels of information for its users. Its channels include CNN and the Wall Street Journal, and these channels can be removed or added by the user.

The technological aspects of channels merit explanation. The essential parts of channels include the role of HTML files which describe screen layout, Javascript files which are referred to by HTML files, and Java Applets. One HTML file (at the top-level URL) is the channel address. The Javascript files provide much of the dynamic capabilities of the channel. At the developmental level, there would be two interpreters (for HTML and Javascript) for layout and event handling, as well as for providing services, such as network connectivity and security (Netcaster's Developer's Guide).

Users of push technology could progress to hooking up a cable modem to personal computers and to television cable in order to receive video webcasting.

While the preliminary stage of push technology utilization does not require functionality such as cable modems for receiving video communication, the next stage would naturally include cable modem usage in order to receive video webcasting. This follows because there is evidence that cable-based access is more cost-efficient and suitable than the Internet access provided by Integrated Services Digital Network (ISDN) telephone service. Cost efficiency was cited as per-subscriber cost per bit of peak bandwidth: $.60 for the 500 Kbps cable service versus close to $16 for ISDN. Suitability or reliability is exemplified with a 4 Mbps cable service providing thirty-two times the peak bandwidth of ISDN (Gillett, 1995).

The boundaries between video webcasting and multicasting are not starkly defined. Video webcasting could include unicasting or broadcasting as its communication method. Video webcasting could also be included as a form of multicasting, which is also conducted over either ISDN or cable networks.

A step forward in solving information overload, multicasting is the sending of a single data stream to Internet Service Providers, and the forwarding of it to everyone who did request it (Berst, February 9, 1998). Clearly this is an improved strategy for information overload on the Internet and can be better understood through description and comparison.

. Starting with the common techniques on the World Wide Web, forms of webcasting, such as push technology can be compared with multicasting. On the World Wide Web, the client browser must request a Web page before it is sent. This is called pull technology. Push technology, in contrast, is "technology used sending data to a client without the client requesting it in client/server applications ("Push Technologies.")." In both cases, the common method used on the Internet is unicasting, the sending of a separate data stream to each person.

The benefits of multicasting coincide with the Internet Multicast Network, which is part of the Internet. These include the support of multicasting by Internet Service Providers, backbone providers, satellite companies, and streaming media companies (Berst, February 9, 1998).

First, ask your Internet Service Provider or System/Network Administrator if there is multicast-enabled feed or multicast packet forwarding or Mbone tunneling capabilities available (Kumar).

Then subscribe to the Virtual Internet Backbone for Multicast IP, or Mbone. This is a co-operative voluntary effort with Internet Service Providers (who route multicast traffic) and end users who install multicast routers at their site. One way to find out more about the Internet Multicast Channel (IMC) availability is to sign up through Stardust Technologies for the IP Multicast Initiative at web site http://www.ipmulticast.com/imc/index.html. This website also explains that the IMC is a schedule of digital content transmissions (webcasts) over Multicast-enabled portions of the Internet. Beginning in December, 1997, the IMC provides three hours of programming, five days a week. The IMC will provide television-style audio/video as well as text, graphics and software for distribution.

To support native IP Multicast, the following are needed: "(1) support for IP Multicast transmission and reception in the TCP/IP protocol stack, (2) software supporting Internet Group Management Protocol (IGMP) to communicate requests to join a multicast group(s) and receive multicast traffic, (3) network interface cards which efficiently filter for LAN data link layer addresses mapped from network layer IP Multicast addresses, (4) IP Multicast application software such as video conferencing ("IP Multicast.")."

The efficiency of multicasting includes having one connection cross country to each local Internet Service Provider or campus at which there are listeners, and then having the data routed to each sub-network as needed (Wiggins, 1997). However, files sent are distributed to all multicast group members, which are the recognized "nodes" such as the Internet Service Providers. This is less than desirable, since not all multicast group members have recipients who requested the sent files. In contrast, anycasting, a newer service, would have requested packets delivered only to routers with the same anycast address (Bay Networks, 1997).

Presumably, utilization of the Open Systems Interconnection (OSI) model could more adeptly explain the technology involved in multicasting and unicasting. The network interface cards which were mentioned before as needed for Internet Protocol (IP) Multicasting provide a clue to the layers of OSI involved: surely the network layer and transport layer if not the data link layer are OSI layers manipulated to provide multicasting.

IP Multicasting is perhaps today's hottest computer technological trend which follows push technology, which was the buzz word for 1997. While both are proposed solutions to information overload on the Internet, multicasting has more efficiency to offer in its delivery of video, audio, animated graphics, real-time financial data and news feeds ("Push."). Multicasting is an extension of push technology, offering benefits of efficient transmittal of information requested by the recipient through the Internet. Predictably, when multicasting is more firmly established and widespread in usage, improvements with anycasting technology could be expected to follow.

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