Voice Blanket Service Has Pros and Cons
I tried the voice blanket class of service using a few different voice-over-Wi-Fi configurations. When used in conjunction with Polycom's Spectralink phones and an SVP server, I found the blanket service worked quite well. Users could roam between my five test APs seamlessly, with no noticeable audio or connectivity effects from handoffs. On the other hand, the voice blanket did not work well in conjunction with some FMC (fixed mobile convergence) tests I conducted last fall. In this case, I found that the mobile phones used in the tests-a Windows Mobile-based AT&T Tilt and some various Nokia phones-could not maintain a connection with the blanket, forcing me to switch the network to the more traditional cell-based data service in order to place a call over Wi-Fi.From the Management Console, I could also access Bandspeed's Spectrum Analysis feature, which displays four distinct ranges of channels (the 2.4 GHz band and three parts of the 5 GHz spectrum). From this screen, I could identify which parts of the spectrum are being affected by RF interference, and I could estimate roughly where the source of the interference is by checking the strength of the signal on multiple APs. Bandspeed could also identify a few sources of interference-specifically microwaves and cordless phones. Unfortunately, the WLAN Management Console doesn't give the administrator nearly enough central control for those who want to take advantage of some of the more advanced features of the system. For example, the access points allow the wireless administrator to create access schedules for each of the various wireless networks-allowing the administrator to grant access only during specified time windows. However, to create these schedules, administrators need to separately configure the rules on each access point to which the service is applied. Also, administrators need to configure the time-or time server-on each AP for the rules to work at the expected intervals. I quickly ran afoul of the management limitations when deploying a voice over Wi-Fi network. By default, the AirMaestro APs offer 2.4 GHz services on radio 1, 5 GHz services on radio 3, and monitoring services on radio 2. In my case, I did not want to offer 5 GHz service, but rather to have a cell-based data network in the 2.4 GHz band on radio 1, and a voice blanket in the 2.4 band on radio 3. But to do this, I again had to individually configure each AP in my network via their Web-based configuration page. Also, firmware management could be daunting with a Bandspeed system. I upgraded the firmware twice during my tests. The first time had to be done from the command line via the service console port on each AP. The second time was a little easier, as I could update each AP from their Web configuration page via a TFTP server. Bandspeed officials said that updates via the serial connection may again be necessary in the future if the baseband needs to be flashed. Senior Technical Analyst Andrew Garcia can be reached at firstname.lastname@example.org.
By default, each 3100AG AP can be managed from its built-in configuration Web page. However, for networks leveraging more than a few APs, Bandspeed also offers a couple of centralized management tools. The more powerful of the two, the WLAN Management Console (an application that can be installed on a Windows-based Server or desktop), gives administrators one place to view much of what is happening in a cluster. I could import a floor map and place my APs accordingly, monitor nearby devices organized by detecting AP, view rogue networks determined by the system to be connected to a protected wired network, view information about clients attached to the cluster, or create new services and assign APs.