Brian's Brain

Continued from 'Powerline Pessimism'....

There is at least one positive outcome to my latest round of powerline network testing, however. My home office contains outlets originating from two different circuit breakers. As part of the debug process, I moved the powerline adapter in the office from one outlet bank to another....and found that I then could obtain a 24-hour-a-day solid link to the power outlet in the hut, even in the middle of the summer. Unfortunately, this migration further degraded the connection to the powerline adapter in the AC closet (or anywhere else relevent in the house, for that matter), even though Intellon's PowerPacket utility indicated a solid link (albeit one which slowed from ~60 Mbps to ~45 Mbps whenever the fan kicked on). PowerPacket, unlike Connection Manager, doesn't provide separate performance reports for each direction of the adapter-to-adapter link, only a generic 'rate' measurement, which constrained my debug capabilities.

Instead, I then remembered that my Broadcom silicon-based Belkin 802.11g access points supported AP-to-AP repeater mode. Wirelessly linking the AP in my office with an AP suspended in the ceiling of the AC closet has restored solid wireless connectivity to all areas of the home. Repeating isn't a perfect solution; as this writeup points out, 'One downside of wireless repeaters, though, is that they reduce throughput on the WLAN. A repeater must receive and retransmit each frame on the same RF channel, which effectively doubles the number of frames that are sent'. But considering the flaky powerline alternative, I'll take the repeater any day.

Next step? Well, I connected with an associate of Valencia, Spain-based DS2 Corporation at the Intel Developer Forum back in August, and they've sent me three 200 Mbps powerline adapters based on the DSS9001 chipset to test. Note: DS2's technology is NOT compatible with HomePlug AV. The adapters are quite slick; among other features, they embed web servers for browser-based configuration, contain notch filters which users can enable if desired (with 20-25% performance degradation) to reduce the interference with ham radio broadcast frequencies, support QoS (quality of service) prioritization of streams with specific user-configurable characteristics, and DS2 claims that the hardware-accelerated optional TripleDES encryption incurs no performance degradation when enabled. I've assigned IP addresses and otherwise configured two of the three adapters; the third arrived right before I left on a string of business trips, and DS2 has also supplied me with PLC (powerline conditioning) filters to (if necessary) suppress interference generated by motors and other nearby-operating equipment.

The only significant glitch I've discovered so far is that while I could direct-connect to a DS2 adapter from my PC in the office (and from there to LAN clients connected to the adapter in the hut), connecting the adapter to the PC via a 100 Mbit switch was unsuccessful. According to DS2's chief technology officer José Calero, "Apparently there was a problem with the last batch of evaluation units that we received from our contract manufacturer. The wrong Realtek Ethernet PHY component was mounted: RTL8201CP should have been mounted, but RTL8201CL was mounted instead. This will be fixed in retail products, so that the end-user does not have to worry about straight or crossover cables". And as before with the 10 Mbit hub-vs-100 Mbit switch in the hut, my use of the 100 Mbit switch in the office represented only a first-step swap with the v1.0 Turbo adapter; long-term, I'll connect the DS2 adapter to my 1 Gbit switch (which supports auto-sense) to avoid switch-caused performance degradation.

Stay tuned for more on DS2's technology after I return to Sacramento this evening. I plan to stick Infrant's ReadyNAS in the hut and copy files between it and my Gigabit Ethernet-equipped PCs in the office in order to log performance. And, of course, I'll also exercise that perpetually problematic office-to-AC closet link. Other suggestions are, as always, welcomed!