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Contact me at david@geercom.com, via this form or at 440-964-9832 (Fax:440-964-2172). The ACUTA Journal of Communications Technology 802.11 Topologies Excel in Higher EdBy David Geer Wi-Fi's real security risks and rumored performance lags seem to be small obstacles to its acceptance among institutions of higher education. With increasing frequency, extending the campus LAN means going wireless. The topologies are often similar from campus to campus, applying one and sometimes two of the IEEE's 802.11x wireless protocols. Most often, 802.11b is the standard selected, either as a precursor to the coming 802.11g (with which it is backward compatible) or because it is so broadly available, having been first on the market. But some campuses have also chosen 802.11a. Referred to as WLAN, Wi-Fi, and 802.11x, these wireless topologies find few roadblocks to implementation among colleges and universities. In this environment, return on investment (ROI) is calculated in terms of savings, value, services, and the investment made in students themselves by enhancing the learning environment. Wi-Fi installations also present few physical challenges. Usually, campus IT departments perform the installations quickly – sometimes in just a few weeks. Once an institution has invested in vendor selection and gathered vendor input, there is little further delay before the proposed WLAN is up and running. Wireless access points (APs) deliver freedom of movement and untethered access at about 6 Mbps (adjusting from the advertised 11 Mbps for about 5 Mbps of overhead traffic, which routes and delivers the payload). Campus constituents seem to be satisfied with this speed – at least for now.
The following is a brief overview of seven campuses that agreed to share their wireless stories. Practical Considerations at Clarion University The Clarion University library is currently served by a wireless LAN of 30 APs optimally placed throughout the building. "The library was recently renovated," says Michael A. Phillips, network and communications manager at the university (mphillips@clarion.edu), "so, as part of that renovation, we wired it with CAT5e cabling, but we also planned for a wireless network." The five-story structure has adequate wireless coverage throughout as well as some outdoor access. The WLAN is interconnected through a dedicated VLAN, set up exclusively for the wireless network. The infrastructure includes Cisco wireless access points, a Bluesocket wireless firewall, and Marconi Ethernet equipment. Clarion chose the 802.11b standard in part based on price and availability. Clarion is strongly considering 802.11g for upgrades, as many campuses are. The 802.11g protocol is not only backward compatible with 802.11b but is also expected to deliver on the promise of 54 Mbps, almost five times the speed of 802.11b.
(802.11a delivers 54 Mbps but is not compatible with 802.11b or g). The 802.11g standard is expected to be finalized this year – perhaps as early as this summer – with some producers like Linksys already rolling out 802.11g products. What about Clarion's wireless hardware? "We're not using the standard, 'off-the-shelf' APs from Cisco with the integrated antennas," says Phillips. Rather, Clarion is using a model from the Cisco 350 Series that adds the option of an external antenna. The Clarion library's drop-ceiling tiles were retrofitted with integrated antennas from Armstrong as part of the networking. "We wanted uniform coverage cosmetically consistent with the rest of the building," says Phillips. Wireless ceiling tiles allow Clarion more control over where the radio signal travels. In dense areas such as Clarion's library, this helps keep any one AP from bearing the load for the whole network. The wireless ceiling tiles keep the service seamlessly invisible to its users. |
