First-Mile Ethernet Makes DSL Choice
Not a major breakthrough, perhaps. But it does put to rest some controversy that had emerged in November, when G.SHDSL and asymmetric DSL (ADSL) camps squared off (see 'First Mile' Ethernet Hits Snags). The matter was settled during last week's Institute of Electrical and Electronics Engineers Inc. (IEEE) meetings in Vancouver.
Ethernet in the first mile is being standardized by the 802.3ah task force within the IEEE. A subset of the standard involves options for delivering Ethernet over copper in the first mile. ("First mile" is the same thing as "last mile" and was changed for marketing reasons. Basically, it refers to the portion of the telecom network that directly connects data or voice services to end users.)
The copper committee had already decided to standardize on very-high bit-rate DSL (VDSL) for connections of 2,700 meters or less. But for longer connections, it became a tossup between G.SHDSLG, a version of DSL created within the International Telecommunication Union (ITU), and what's called ADSL Annex J, an enhanced version of ADSL (see First-Mile Ethernet Camps Dig In).
G.SHDSL was supported by RBOCs and was likely to be accepted into the standard regardless. The camp supporting ADSL was holding out hope that the standard would include both types of DSL, but there was some suspicion that that wouldn't jibe with IEEE rules. In the end, G.SHDSL took the prize alone.
"Annex J isn't fully available yet, and that was part of the decision," says Behrooz Rezvani, CTO of Ikanos Communications Inc.
Ikanos was an ADSL backer in this argument, but Rezvani says he's fine with the choice the task force made.
"It's positive that the committee made the decision," Rezvani says, although he adds, "We think a bigger market potential can be reached by including other DSL types.”
Ikanos officials say VDSL is where the Ethernet-DSL action is going to be anyway. G.SHDSL is relatively slow, maxing out around 2.3 Mbit/s. VDSL, by contrast, runs at 26 Mbit/s -- split symmetrically or not, depending on which version you're using -- and Ikanos officials say they've gotten the speed up to 50 Mbit/s, or 25 Mbit/s in each direction, with their proprietary technology.
"When you say 'Ethernet,' the first number that comes to everybody's mind is 10 Mbit/s. So, VDSL is going to be the dominant deployment for [Ethernet in the first mile]," Rezvani says.
— Craig Matsumoto, Senior Editor, Light Reading