I got the opportunity to chair a VDSL panel at the recent Spring DSLcon and was impressed by how much of the conversation centered on Ethernet at Layer 2. Ilan Bluvstein, strategic-marketing manager of the access business unit at Infineon Technologies Inc., said the fact that the IEEE's 802.3ah Ethernet in the First Mile group is putting such emphasis on VDSL for its Ethernet copper interface shows that there may soon be a victory for what Bluvstein calls "phantom VDSL-it's phantom because it comes in under the radar."

It's also a way for Infineon, Broadcom and other companies to promote quadrature-amplitude modulation for VDSL again. Although several groups have promoted two types of coding for VDSL, proponents of discrete multitone have remained in the front seat in traditional VDSL deployments. Enter Ethernet-over-VDSL.

The IEEE wants one Ethernet-in-the-first-mile physical interface for copper, and this must be based on VDSL. ATM cannot be used in a home networking environment easily, but traditional Ethernet is limited to a 400-foot reach and Category 5 wiring. Bluvstein said Infineon is promoting Ethernet over QAM as "a Media-Independent Interface extender," since it allows full-duplex transmission over 4,000 feet. This fits fairly well with Infineon's earlier 10 Base S concepts.

But the whole concept isn't just interesting because Infineon and other QAM cheerleaders are promoting it. Pat Evans is the vice president of product marketing at Kenetec, a DSL service provider focusing on the multitenant market. He said he's already seen a request for proposals from a customer in the United States that specifies Ethernet-over-VDSL, rather than ATM-based VDSL.

The interesting thing here isn't the dredging up of a tired QAM vs. DMT coding battle. The intriguing aspect is the dwindling opportunity for ATM framing in the last mile, where Ethernet rolls over everything in its path. Wonder what this implies for existing ADSL environments?