Going wireless may avoid the expense of cabling and wired LAN drops, but wireless networks still require effective technical support and troubleshooting. According to Momenta Research, ongoing support represents 45% of a wireless LAN's total cost of operation. Efficient wireless troubleshooting contains that cost while avoiding downtime that can sap productivity benefits.
Smooth operation starts with a well-designed wireless LAN (WLAN). Site surveys, RF modeling, and automated RF management systems are all investments that pay dividends by reducing help desk calls. But no WLAN can escape the need for troubleshooting. Environmental conditions and network usage change. Equipment failures and software glitches occur. Eventually, wireless users require assistance. Good troubleshooting tools and a systematic approach can help you isolate and resolve those problems faster.
Processes and tools
When it comes to WLANs, conventional network management systems and diagnostic utilities are crucial, but insufficient. Many "wireless" help desk calls are caused by upstream network or application failures. But determining that -- and isolating true WLAN failures -- requires new tools and techniques.
Many WLAN adapters are accompanied by wireless client utilities such as Cisco ADU and Intel PROSet. These vendor utilities can provide connection status, data rate, signal strength, and other basic information for triage during that first help desk call.
Help desk staff can also assess the situation remotely using a wireless intrusion detection system (WIDS). A WIDS -- or a WLAN switch with remote monitoring capabilities -- lets you query the user's current status, recent activity, and related alerts representing deviations from security policy or expected pe
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rformance.
Problems not easily resolved must be assigned to a technician for further investigation. That technician may put a WIDS sensor near the user into filtered capture mode, analyzing wireless traffic in hopes of isolating the problem without an on-site visit.
Of course, some issues simply cannot be diagnosed remotely. Any technician dispatched to the user's location should be armed with a portable WLAN traffic analyzer and a wireless spectrum analyzer to enable passive observation, multi-layer traffic analysis, and active diagnostic testing.
Trouble isolation
Problems experienced by wireless users run the gamut, from radio interference and client misconfiguration to loose access point LAN cables and cranky applications. As with wired troubleshooting, a systematic approach is needed to track down the problem without overlooking common causes or running in circles. And following the connection from client to server, verifying operation of every component in between, is still a sensible approach for wireless. Doing this simply requires an understanding of wireless devices, protocols and your own WLAN's architecture.
[TABLE]About the author
Lisa Phifer is vice president of Core Competence Inc., a consulting firm specializing in network security and management technology. Phifer has been involved in the design, implementation, and evaluation of data communications, internetworking, security, and network management products for nearly 20 years. She teaches about wireless LANs and virtual private networking at industry conferences and has written extensively about network infrastructure and security technologies for numerous publications. She is also a site expert to SearchMobileComputing.com and SearchNetworking.com.
