Wireless Features - more
The Advanced Wireless settings (Figure 13) are generally more understandable than some of the options exposed by the Buffalo Nfiniti Dual-Band router. You get High / Medium / Low Transmit Power settings and the usual set of tweaks for Beacon Period, RTS and Fragmentation Thresholds and DTIM Interval.
Figure 13: Advanced Wireless settings
It's nice to see the L2 Isolation control, which keeps wireless clients from being able to communicate with each other (default disabled). The simple WMM Enable control (default enabled) is interesting to see, given all of the Ubicom intelligent QoS capability built into the 655. But ya can't get Wi-Fi Certified without supporting WMM, so there it is. Someday, I have to see if WMM really does anything useful.
The last option, Short GI, is enabled by default and used to set the time that the receiver waits for RF reflections to settle out before sampling data. The D-Link help offers the following as guidance in setting this feature:
Using a short (400ns) guard interval can increase throughput. However, it can also increase error rate in some installations, due to increased sensitivity to radio-frequency reflections. Select the option that works best for your installation.
I left this in its default for all of my testing and didn't notice any problems that could be attributed to it.
Note that if you set the 802.11 mode to 802.11g only or mixed 11g / n, then an Extra Wireless Protection checkbox will appear that controls the protection mechanism for 802.11b WLANs that is part of the 802.11g spec.
In addition to the WMM support mentioned above, the 655 supports Ubicom's WISH (Wireless Intelligent Stream Handling) technology, which according to Ubicom "automatically and continuously looks for media streams on the wireless link and ensures that they are transmitted at the appropriate priority". Put another way, WISH applies the same automatic prioritization technology that the 655 applies to upstream Internet traffic, to traffic between the 655 and wireless clients. However, WISH won't work miracles, or create bandwidth. So if you're trying to run an HD stream over a 10 Mbps wireless connection, WISH isn't going to keep you from getting a choppy and unwatchable picture.
Finally, note that D-Link has taken the typical wireless MAC Address Filtering and applied it to both wireless and wired connections. The Network Filter feature can be set to allow or deny listed clients and provides pick lists of any clients that have obtained addresses from the 655's DHCP server. Note that this feature does not work when the 655 is in "Bridge" (AP) mode. So, in that case, you give up any MAC address filtering.