Push Can Be a Pig
By John Graham-Cumming
April 1997
HTTP (HyperText Transport Protocol) is the common protocol that Web sites use to deliver their information. We looked at the flow of HTTP traffic that PointCast uses to push its information. What we found was intriguing: From a group of about 4,000 users, just 12 percent had the PointCast Network installed on their machines, but this group was the biggest user of bandwidth, sucking up 17 percent of network traffic.
By comparison, Netscape's home page came in second with 12 percent of traffic, with a user community of about 70 percent. Hence, PointCast was having a disproportionate effect on the network. This should worry any network manager considering whether PointCast is necessary to his or her business.
PointCast had this impact primarily because push technologies act without user intervention (the client updates its information automatically). That's why PointCast goes to some length to enumerate ways of configuring for optimum network use. Suggestions range from increasing the interval between updates (so that the impact is less frequent) to leaving computers on overnight so that updates occur when there's less traffic. Through such configurations, users, in theory, can alter the PointCast browser to have less effect on the network. But will they bother, or does this become yet another responsibility of overworked network staffs?
One reason that Netscape ranks second in bandwidth use is that it's the most widely used browser, and netscape.com is the default that appears at startup. (Microsoft Corp.'s Internet Explorer does the same thing, jumping to its own site first.) We learned from our study that most users quickly jump to a different site before Netscape's download finishes. By changing the preferences, users can specify another startup site and save a sizable chunk of that 12 percent of the network they use--but they don't. Push technologists must keep in mind that users are reluctant to--and in corporate environments, sometimes even discouraged from--touching default settings.
Because information often flows into companies through restricted connections (a corporate Internet service provider, or ISP, for example), it may be useful to install a special server called a proxy to control the data stream. Proxy servers provide a feature called caching, which allows them to store a copy of frequently sought Net information and reply directly to requests from users, rather than going out to the Internet each time. A proxy may store a copy of CNN's home page, for example, and serve it to multiple users, having taken it once from www.cnn.com. Caching saves significant bandwidth by reducing the size of the Internet pipe required.
Rather than using just any proxy, such as Microsoft's free downloadable Proxy Server, PointCast hopes you will opt for its I-Server because in addition to saving bandwidth, you can open your own "channel" and broadcast company information to every desktop.
Our survey, however, revealed that 36 popular sites accounted for 50 percent of traffic. That means the other 50 percent came from accessing thousands of miscellaneous sites. As a network becomes more diverse, caching becomes less effective.
What's an intranet manager to do? Hire smart network engineers; don't rely on caching to cure all ills; use PointCast or another push browser as an intelligent agent to broadcast through your network. Since we probably have to live with it, make push technology work for you rather than against you.--John Graham-Cumming
John Graham-Cumming ([email protected]) is director of product architecture at Optimal Networks Inc. His study,"Hits and Misses: A Year Watching the Web" is available at: www.optimal.com under What's New.
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