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HomeGrid and HomePlug Will the incompatibility between HomePlug and G.hn cause problems for property owners trying to deliver high-bandwidth services to residents? By Steven S. Ross ■ Broadband Properties
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his issue carries a comprehensive explanation of the new G.hn standard for home networking. Because G.hn operates seamlessly on multiple kinds of wire at the same time – including coax, Ethernet Cat 5 and Cat 6 (even Cat 3) cable and HDMI – and even connects to Ethernet wireless networks, G.hn will make it easier to deliver services to dwelling units without expensive rewiring. Eventually, G.hn and HomePNA (IEEE 1901) will probably become the worldwide choices for dwelling units without structured wiring. But for the near future, G.hn is just another way to make flexible, high-performance home networks possible at a reasonable price. Other standards will work about as well if the existing wiring is suitable for them. G.hn coexists easily with MoCA (coax-based Ethernet networks) and HomePNA. For instance, networks running on G.hn and MoCA can be installed and active at the same time, although they cannot exchange data directly. (Failure to exchange data is not a major problem because appliances such as PCs and newer TVs can interact with multiple networks at the same time.) Unfortunately, G.hn is not yet assured of coexisting with HomePlug, the protocol for moving Ethernet over electrical wiring. The emerging version of HomePlug should be compatible with G.hn, but there is no approved final mechanism for ensuring that. MDU owners and managers who adopt G.hn and expect to use electrical wiring for the network must be on the lookout for tenants’ installing retail HomePlug Ethernet adapters by plugging them into electrical outlets. Such installations, using HomePlug versions currently on the market, could bring down a G.hn network.
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HomePlug Not Ready Fortunately, such conflicts should be rare, despite the 35 million HomePlug adapters already sold (good for about 17 million two-node home networks). Unfortunately, the HomePlug folks have been rather slow off the mark. That may create problems well into the future. To understand why, one has to look more closely at exactly what the ITU did in October. Though G.hn was not finalized, its key components were – the general G.hn architecture and the PHY, or physical network layer. Thus, G.hn is now stable enough to allow chip vendors to bring products to market. Another important aspect, proposed Recommendation G.9972, allowing coexistence between G.hn products and other wireline networking standards, achieved ITU consent, the final step before a recommendation becomes a standard. The G.hn Data Link Layer portion of G.hn was also deemed stable but consent is not expected until the January 2010 ITU-T meeting. “G.hn will empower service providers to deploy new offerings, including IPTV, more cost effectively; allow consumer electronics manufacturers to network all types of entertainment, home automation, and security products throughout the house; and greatly simplify consumers’ purchasing and installation processes,” says Matthew Theall, president of HomeGrid Forum, the trade association promoting G.hn. The HomePlug folks, who exploded in anguish at last winter’s delay, exploded in anguish once again, issuing a
press release that called the delay in consent for G.9972 “a significant setback for G.hn and another clear indication that the powerline networking industry is not aligning around G.hn.” Part of the delay has to do with likely requirements for the smart-grid initiative included in the U.S. stimulus package in February but not finalized until late spring. Only in June did AT&T (a supporter of both G.hn and HomePNA) and others begin to submit ideas to ITU to align G.hn with smart-grid requirements. But in October the G.hn working group could not agree on many criteria for a smart-grid device profile, or even on an informational appendix describing how a G.hn smart-grid device might be configured. In fact, the group could not even agree on what a smart grid might include. The HomePlug folks say this will delay final design of G.hn chips until 2011, keeping fully certified G.hn products from shipping until mid-2011. Nextgeneration HomePlug AV2 chips and smart-grid GP chips should be available by next spring. HomePlug promises compatibility and full interoperability with HomePNA. However, this is not a competitive race, although HomePlug is treating it that way. All the technologies have their place in bringing broadband to the last few feet. And if the folks at HomePlug think that all MDU networking problems can be solved by using electrical wiring, this bandwidth hawk says the notion is absurd. BBP
About the Author Write to the Hawk at
[email protected].
| BROADBAND PROPERTIES | www.broadbandproper ties.com | October 2009
