HomePlug AV: Partial Powerline Progress (And Other LAN Thoughts)

Four weeks ago, I told you about my inability to stream audio from iTunes v8 to my Apple TV across a HomePlug AV powerline networking spur. My continued experimentation has uncovered some interesting results, so even though I’m still getting ‘unknown error (-15000)’ notifications, I figured an update was due for all of you.

Intellon hasn’t been able to replicate my issue using HomePlug AV-based adapters, although it should be noted that the company representative I’m working with isn’t using the same router I have. Given my past experiences, I suspect that the Linksys WRT54GC is a factor in the issue I’m having. Ironically, Intellon tells me that it’s seeing the same error I am, but with powerline networking adapters based on competitor DS2’s technology.

I can’t personally confirm or deny Intellon’s claimed results, but if they’re true, they should also give the company insight into the reason for the problem I’m having…the protocol restriction is likely the same. Apple’s support documentation points to misconfigured IPv6 and UDP settings as possible root causes. I’ve previously mentioned that I don’t get the error if I connect Apple TV to the router via Wi-Fi…this is true with the MacBook in a default configuration mode. However, even with this particular Apple TV connectivity option, I’m able to artificially generate ‘-15000′ errors by temporarily disabling either IPv6 or UDP support in the MacBook’s (respectively) network and firewall (sharing) settings.

As previously mentioned, I’ve discovered another workaround to my iTunes streaming problem. I can route the audio coming out of iTunes (in the normal fashion) through Rogue Amoeba’s Airfoil, from which it streams to the Apple TV-as-Remote Speaker set just fine even with Apple TV connected to the router over HomePlug AV. iTunes v8 seems to require some network protocol nuance that Rogue Amoeba’s reverse-engineered implementation of Apple’s streaming audio compression and encryption schemes does not demand, and Airfoil is still able to converse with Apple TV just fine.

As part of the to-date debug process, Intellon sent me six replacement adapters from NETGEAR. They run a newer firmware version than the one in my previous Actiontec adapters; the new adapters are also based on a newer INT6300 chipset from Intellon. I’m pleased to report that, in over 1 week of testing to date, the newer units seem to be much more robust than their predecessors both in base functionality (the ability to make and long-term sustain a link with their peers on the powerline network) and in robustness and consistency of performance over time. Here’s a screenshot of my setup captured late Friday afternoon:

To obtain it, I ran NETGEAR’s configuration and status utility from my Windows Vista-based Dell laptop (which at the moment is mostly acting as a glorified TiVo HD) at one end of the house and connected to adapter Device 1. The other adapters are used as follows:

• Device 2: connected to two Apple Power Macs in my office on the other side of the house, via a GbE multiport switch
• Device 3: connected to the router in the middle of the dwelling
• Device 4: connected to a home theater stack (Xbox 360, PlayStation 3, Apple TV) in the living room via a 10/100 Mbit multiport switch
• Device 5: connected to a Universal Devices INSTEON-based home automation controller (yes, that’s right…powerline-based home automation, linked to the router via powerline networking), and
• Device 6: connected to a home theater stack (Xbox 360, Roku Netflix Player) in the bedroom via a 10/100 Mbit multiport switch

Note that the reported bandwidth is an estimate of potential link speed, not of the actual throughput delivered by an adapter. NETGEAR’s XAV101s (like their predecessors) embed 10/100 Mbps Ethernet transceivers versus GbE PHYs, a cost-vs-performance tradeoff that puts an upper-end cap on the link performance potential. Indicative of this reality, I also last night grabbed screenshots of the Windows Vista Media Center’s measurement of link bandwidth to the Xbox 360 (acting as a Media Center Extender) downstairs:

and upstairs:

It’s curious to me that NETGEAR has chosen to add HomePlug AV-based adapters to its product line. As I’ve previously noted, the company’s powerline networking portfolio has historically been a mish-mash of diverse technologies; industry-standard HomePlug 1.0 at the low end, Intellon-proprietary (albeit HomePlug 1.0 backwards-compatible) HomePlug 1.0 Turbo at the ‘85 Mbps’ threshold, and DS2-based devices at the high-end ‘200 Mbps’ point. According to DS2, NETGEAR replaced the DS2-based HDX101 adapter with the HDX111 in January; at that same time, NETGEAR added HomePlug AV-based units.

Interestingly, the HDX111 isn’t available standalone, only in two-adapter kits…the previous-generation HDX101 is still for sale in single-adapter fashion, but at a $20 increment to its HomePlug AV-based competitor. Couple these facts with Cisco/Linksys’s latest in a series of statements of support for HomePlug AV (and HomePlug 1.0 Turbo) last week, marking a similar product lineup to that of Belkin…but in contrast, note that D-Link’s powerline networking gear is still DS2-derived. The North American ‘big four’, it seems, still haven’t settled on a consistent ‘200 Mbps’ approach.

In my case, however, I suspect that my use of powerline adapters may decrease (albeit not completely disappear, given my distaste for navigating dirty, cramped crawlspaces, drilling holes in floors and running Cat 5e cable) over time. Right now, the only reason that the Dell laptop (aka glorified TiVo HD) is HomePlug AV tethered is that I’m still using an 802.11g-only router. However, I remembered the other day that the Dell system is 801.11n-capable, as is an increasing percentage of my overall Wi-Fi-equipped hardware portfolio (the MacBook, the Apple TV, and another piece of gear I’ll shortly tell you more about).

As such, I soon plan to migrate to an 802.11n-inclusive router. I suspect it’ll be Apple’s Airport Extreme, even though unlike Linksys’ WRT600N (for example) it doesn’t simultaneously broadcast on the (interference-plagued and 802.11b/g client performance-throttled) 2.4 GHz and (comparatively uncrowded) 5.8 GHz bands. Why, then? If I attach a USB-interface hard drive to the Airport Extreme, I can do automatic periodic backups to it via OS 10.5’s Time Machine feature…albeit in an officially unsupported fashion.

p.s…one other minor powerline networking note. Last night I stuck a noise filter in-between the AC outlet and my under-house furnace, as well as in-line enroute to the refrigerator (specifically, its compressor). Every little bit helps, I figure…