Guide to WLAN Management
Top trends in wireless management encompass 802.11n, VoIP, converged mgmtBy John Cox
As enterprise WLANs change from being merely convenient to being mission critical, there's a growing demand from network managers for more data, more control, more help in managing them.
A 2007 Aberdeen Group survey of enterprise WLAN deployments found that "best-in-class" enterprises – those reporting the highest performance and productivity gains attributable to wireless networking – consistently knew more about their WLAN, had greater control over it and enforced corporate policies on it.
Of the top performers, 88% had policies for centralized WLAN management, and 57% had IT professionals specifically trained in WLAN technology. Nearly all the best-in-class companies had manual procedures in place for ongoing radio frequency (RF) site surveys. And 44% monitored the wireless net at least monthly.
For these companies, the WLAN is no longer seen as a convenient add-on to the enterprise net but as the primary means of client access.
One developing trend is the integration of wired and wireless corporate nets, creating a single, managed infrastructure. Cisco, for example, has been talking about this for at least two years. And last year, switch vendors began some introductions of "unified" LAN switches that use new silicon and software to handle both wired and wireless clients.
But this trend is developing slowly. Much of the initial focus is on integrating higher-level management functions for such areas as security and performance evaluation. One issue to consider if you have a mixed-vendor WLAN is weighing the management capabilities offered by WLAN vendors against those offered by third-party software vendors specializing in management.
More pressing are the concerns raised by the introduction of high-throughput WLANs based on the draft IEEE 802.11n standard, which promises WLAN data rates of 300Mbps, compared with 54Mbps for 802.11g and 11a nets today. But 11n introduces new technologies and new behaviors on the 11n WLAN. At least in some cases, updated net management software is lagging the new 11n access points and updated controllers. Vendors should be racing to ensure their 11n management software and features are as complete as possible, as soon as possible, to ease this transition for enterprise customers.
The prospect of running VoIP traffic over enterprise WLANs introduces a new set of issues, because this kind of traffic is especially vulnerable to latency, which is the one-way delay between a sender and receiver on a network, and jitter, which is the amount of variation in the arrival times of VoIP packets. More vendors are introducing features to monitor and manage voice traffic.
A related development is the growing number of enterprise-based systems designed to seamlessly bridge voice calls between cellular nets and WLANs. Start-ups like DiVitas and established companies like Siemens are all getting into the act. Typically, these involve a network appliance with software and close integration with an IP PBX. But so far, there seems to be little integration of these systems with the WLAN management infrastructure.
Still in development are IEEE standards that will increase management of WLAN clients. The 802.11k standard for radio resource management specifies a radio measurement data interface, allowing the WLAN infrastructure to collect statistics on the 802.11 physical layer and media access control layer for all radios, including clients.
The 802.11v standard defines a set of common control commands and protocol messages that among other things will let the infrastructure reach out to control key parameters on client radios. The standard also provides a means to control SNMP management information bases on WLAN clients.
Some vendors are implementing early versions of these or have comparable functions.