Tuesday, October 23, 2001

Colleges Experiment With Routing On-Campus Phone Calls Over the Internet By FLORENCE OLSEN On the morning of September 11, the day of the terrorist attacks, many students at Columbia University tried to make phone calls to family members and friends, but Manhattan's telephone networks were overwhelmed by demand. Yet within a few hours, networking specialists in Columbia's School of Engineering and Applied Science had opened up a conference room where students were able to make national and international calls over the Internet. Specialized telephones had been hastily configured to route outbound calls through several Internet gateways to the public telephone network. Apart from its unprecedented use as an emergency system that day, telephone service over the Internet is still largely a research activity. But at a small and increasing number colleges, the technology known as Internet Protocol telephony -- IP telephony, for short -- is being used to replace campus-telephone networks. Menlo College built an IP phone network as part of a recent $1.9-million renovation of its campus information-technology infrastructure. Jackson State University recently switched its campus telephone service to IP telephony. Both institutions had relied previously on more costly Centrex service, a central-office exchange service provided by local telephone companies. For several years, a group within Columbia's computer-science department has operated a 100-line IP phone network, which it set up to avoid local Centrex phone charges. More recently, both Brigham Young University, in Provo, Utah, and Touro College, in New York City, announced plans to operate local phone services over their campus IP backbones. "We used to pay about $11,000 a month for our 100 administrative telephones," says Patrick Olson, the director of information technology at Menlo, in Atherton, Calif. "We pay about $1,000 now." Menlo bought Cisco Systems AVVID components for its network. Jackson State, in Jackson, Miss., is installing an Alcatel Omni PCX system. Colleges that have set up IP phone systems generally have done so after upgrading their campus networks. Both Menlo and Jackson State now have gigabit Ethernet backbones. "These kinds of networks are very hard for people to fill up," Mr. Olson says, noting that providing telephone service over such networks uses a relatively small amount of the networks' capacity, or bandwidth. A single telephone call, for instance, takes only a small amount of bandwidth -- 64 kilobits per second. Network administrators need to figure on having that much bandwidth in reserve for each phone call that might be made during peak times, Mr. Olson says. His rule of thumb is this: If 100 students live in a dormitory, as many as 20 of them might be making phone calls at any one time. "You multiply 64 kilobits times 20 -- and set aside that bandwidth," he says. Even that worst-case scenario would demand only a fraction -- less than 1 percent -- of the campus network's capacity. Colleges tend to worry more about downtime than bandwidth when they merge their telephone and data networks into one. If the IP network goes down, Mr. Olson says, the college loses two of its essential communications systems -- e-mail and phone service. But institutions can prevent that from happening if they design their networks properly, he says. "Redundancy is the key to making this stuff happen well." Menlo has a relatively small IP telephone network of 500 phones with "redundancy everywhere," says Mr. Olson. Instead of one call-manager server, Menlo installed two. "If one goes down, the other one does the work," he says. The call managers have separate electrical sources, and each electrical source is backed up with its own redundant power supply. The emerging use of IP phone systems on campuses shows the degree to which institutions have become dependent on their IP networks, says Henning G. Schulzrinne, an associate professor of computer science and electrical engineering at Columbia. The networks "tend to be pretty reliable," he says. Most network outages are due, he says, not to failed switches or faulty wiring. Rather, the sources of failure tend to be in what he calls the network's "supporting infrastructure" of e-mail servers, Web servers, and file servers. But with a little bit of care, he adds, even those parts of the network can be designed not to fail. Campuswide IP phone networks could pose new operational problems for some large institutions, Mr. Schulzrinne says. Most student-information systems, for instance, don't yet have a way of automatically updating network databases when student telephones are added, moved, or changed. Solving that problem, he says, will provide not only the biggest cost savings of IP telephony, but also the biggest "aggravation savings." He also says that as colleges switch to IP phone service on campus, they may need to reorganize their telecommunications and network personnel to reflect the convergence of technologies, and that could be a sensitive issue. "People are somewhat afraid to tread there, because vice-president positions are at stake, and that seems to get people very nervous," he adds. At institutions that offer IP phone service, it usually is confined to the campus -- or to several campuses, if the institution has high-speed Internet connections between different campus locations. In that way, colleges "can control the links from both ends" and also avoid local phone charges, says Walter R. Magnussen Jr., the associate director for telecommunications at Texas A&M University at College Station. Texas A&M has a voice-over-IP test lab in its engineering-technology and industrial-distribution department. Setting up voice service over IP networks is a bigger challenge beyond the confines of the campus, says Mr. Magnussen. The Internet is an IP network designed for file sharing and other services that can tolerate a high incidence of "packet loss," he says. Phone service is different from file-sharing and Web surfing -- because those uses aren't time-sensitive, the network can simply wait until tardy packets show up, and then incorporate them into a file. But voice calls can't wait, so delayed or missing packets degrade the sound quality. Mr. Magnussen says one way to prevent poor-quality phone service over the Internet is to add software to routers that lets them distinguish telephony packets from other kinds of data -- and make sure that the telephony packets get delivered without loss or interruption, even when the routers become congested. National and international phone service over the commercial Internet may be "years and years away from happening," he says, "because it's hard to negotiate quality of service" when the equipment of many competing carriers is involved. An alternative is for institutions to buy enough Internet bandwidth that they never experience congestion when they place voice calls, a solution he calls "just plain over-provisioning." As the cost of bandwidth drops, buying large quantities may become an attractive option for colleges. Mr. Magnussen, who is the head of a committee experimenting with IP telephone service over Abilene, the high-speed Internet2 network, says that a lot of problems still need to be solved before IP telephony can work on a large scale. But he says he is confident that those difficulties can be overcome. "If properly designed and properly engineered," he says, "voice over IP is great stuff; it's fantastic." Background article from The Chronicle: College Uses Internet to Carry Voice Calls (4/6/2001) Easy-to-print version E-mail this article

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