Original URL: http://www.theregister.co.uk/2009/10/12/ghn_phy_agreed/

Vendors promised G.hn chips as ITU agrees PHY spec

Unified home networking standard takes major step forward

By Tony Smith

Posted in Broadband, 12th October 2009 11:50 GMT

The International Telecommunication Union (ITU) has given its blessing to a key component of G.hn, the prospective standard for data networking over mains wiring, home phone lines and coax cabling.

As is the case with all standards organisations, the wheels move sure but slow. There are many more steps to take before G.hn becomes a formal standard, but the specification has now reached the stage - known as an "Approved Recommendation" - where companies can begin to develop products that implement the technology, safe in the knowledge that it isn't going to change to any appreciable extent.

The agreement, announced last week, covers G.hn's physical layer (PHY). The Data Link Layer (DLL) specification was said to be "stable" but this won't gain ITU's "Consent" until January 2010, with ratification a way down the line after that. The G.hn PHY achieved a similar Consent status in December 2008.

Also last week, the ITU marked up Recommendation G.9972, which governs, coexistence with existing powerline adaptors, as achieving the Union's Consent.

Almost immediately, powerline Ethernet chip maker DS2 said it will go ahead and develop its DSS9960 chipset for G.hn-based products, though since it's long been a G.hn supporter that's no more or less than expected.

Once again, DS2 stated its plan to ensure DS9960-based products work with older 100Mb/s and 200Mb/s products based in the Universal Powerline Association (UPA) standard.

UPA competes with HomePlug, which has favoured the IEEE's attempt to create a unified home wired networking technology, P1901.

G.hn uses a single combined PHY/MAC for all three cabling types. P1901, on the other hand, specifies three, incompatible PHY/MACs combos. Vendors can use any or all of these, ensuring buyers need to check beforehand which kinds of wiring a given product supports. They can't just assume compatibility from the P1901 branding. They can with G.hn.

In any case, P1901 has a G.hn compatibility requirement. If you're going to design P1901 kit, then you may as well just stick with G.hn and have done with it. That, G.hn's backers reckon, renders P1901 an irrelevance. ®

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