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Contact me at david@geercom.com, or at 440-964-9832 (Fax:440-964-2172). The ACUTA Journal of Communications Technology 802.11 Topologies Excel in Higher EdBy David Geer Meeting Many Needs at OIT "Basic service set [BSS] is the current layout for Oregon Institute of Technology [OIT] wireless networking. Each AP is connected to a wired Ethernet jack," says Agnes Box, telecommunications coordinator, information technology systems, OIT (boxa@oit.edu). As with other 802.11 topologies, there is some overlap of coverage by APs in order to ensure sufficient coverage everywhere. OIT used products from vendors Cisco and Avaya (formerly Lucent), already familiar from their use at other Oregon University campuses. Specifically, these are the Avaya Wireless Access Point-3 Ps with power-injected Ethernet, silver and gold wireless cards, and antennas from Avaya, which were once the WaveLAN products. Criteria used for evaluating 802.11b solutions included the number of users connected at any one time, the ease of migration, and scalability. OIT will likely migrate to 802.11g to meet eventual demands for greater speed. Campus topology will probably evolve to extended service set (ESS) when this happens. With ESS, overlapping broadcast rings will provide roaming from building to building. As a natural enhancement to the network, the corrugated metal buildings at OIT act as antennas, sending a strong Wi-Fi signal throughout the buildings. An Integrated System at Collegis/Salt Lake Community College Larry Maughan's team at Collegis/Salt Lake Community College went to Proactive Network Management Corporation "for engineering, coordination, and support in integrating [wireless] into the existing network," says Maughan, director of netcomm (larry.maughan@slcc.edu). Collegis/Salt Lake is now implementing VLANs as a solution to conflicts between APs. Future services will expand to include PDAs (in trial mode now) and soft phones. As it has for other institutions, 802.11b have been very reliable for Collegis/Salt Lake. The Cisco LEAP security product manages security, and all users are required to log on via an account on the active directory. The only problem seems to arise from weeding out bad APs. The process will be greatly unburdened by the adoption of the Cisco Wireless LAN Solutions Engine (WLSE), which will allow remote identification, location, troubleshooting and configuration of APs.
Until this solution, Collegis/Salt Lake has been searching for bad APs manually by touring the suspect coverage area with wireless laptops upon notification of the problem to technical support. John Dunn and Proactive Network Management Corporation helped Maughan and his group with their wireless deployment. Together they set up 802.11b coverage for 13 sites including four major campuses – every room in every building. "We used Cisco ACS products for the authentication, and then it was tied back into its closest switch where it also receives its power," says John Dunn, president of Proactive Network Management (john@pnmc.com). Maughan and his team did most of the design, and the two organizations worked together on the site survey and implementations. Seeking Security at Bridgewater State Using Enterasys R2 APs and Cisco switches, director of telecommunications Patrick Cronin (pcronin@bridgew.edu) and the Bridgewater State College team set up 802.11a. As the topology evolves from a simple routed network, Cronin plans for "some sort of solution to segment the collision domains without requiring an additional login as you roam." Bridgewater is considering Bluesocket, Vernier, and other solutions. As far as security goes, "Right now we don't allow access to our administrative systems from the wireless network," says Cronin. However, as Bridgewater comes to rely more and more on the wireless network, more critical data will be transferred over it, and security will become more of an issue. Just as many other institutions today, Bridgewater is conservative about plans for services in addition to WLAN. It has taken a glance at 802.11b phones. Enterasys helped Cronin set up Bridgewater's 802.11a network. When asked about the topology, John-Paul Gorsky, director, wireless product line, at Enterasys (gorsky@enterasys.com), said, "The typical topology you will see is buildings, or floors in buildings, connecting back to the intermediate distribution frame on the particular floor." The wireless topology depends a lot on what the wired topology is – whether the wired networks on each floor are individual subnets, for example. Roaming works best on the same subnet. Conclusion There are a variety of ways to approach implementation of 802.11 protocols, and a selection of hardware solutions is available. Flexibility, keeping your options open for the future, seems to be the secret of success. Sidebar The 802.11 standard and the FCC The FCC doesn't require licenses for any of the 802.11 protocols and so these are freely used. "Since the FCC does not require licenses for use of the 2.4 GHz or the 5.15-5.35 and 5.725-5.875 GHz spectrum bands, companies may develop products and services according to business plans that they think will best suit users – subscription, free or whatever," says Anita Wallgren, attorney at Sidley, Austin, Brown, and Wood, LLP (awallgren@sidley.com). Wallgren notes that the FCC does, however, stipulate that companies obtain Part 15 certification for the APs and receivers. This is in order to meet power and performance specifications. The unlicensed spectrum model for 802.11 will likely continue due in large part to its level of success. |
