The Redback Networks Inc. portion of Ericsson AB (Nasdaq: ERIC) is suggesting some new energy-usage metrics for edge routers, contributing to the ongoing effort to lower the power consumption of telecom gear.

Ericsson's thesis is that in its obsession to go green, the industry needs to develop metrics that take into account the different needs of different network segments. "It's not so much about new methodology. It's about putting the results in a more meaningful form for carriers," says Jeff Baher, senior director of product marketing at Ericsson.

The work is part of an ongoing Ericsson effort to make its products more energy-conscious, but it also ties in with a greater telecom and networking trend toward lower energy consumption. (See Recent Moves in Green Telecom and Green Telecom Preview.)

Ericsson has two ideas in particular that it's announcing today: measuring Watts per subscriber at the edge of the IP network, and Watts per circuit in the metro network.

Ericsson says it's not trying to start a shouting match with other vendors, such as Ixia (Nasdaq: XXIA) and Juniper Networks Inc. (NYSE: JNPR). Last fall, those companies developed the Energy Consumption Rating (ECR) as a way to repeatably measure the greenness of a piece of equipment. (See Ixia, Juniper Start Counting Green.)

Rather, Ericsson wants to run its ideas past the Alliance for Telecommunications Industry Solutions (ATIS) , which crafted the Telecommunication Energy Efficiency Ratio (TEER) ratings that are highly regarded by carriers.

"The debate is not so much the methodology. The debate would be whether this is practical," Baher says of Ericsson's metrics. "What isn't in [the TEER] equation are ways to drive Watts per subscriber, Watts per VLL [virtual leased line], or Watts per MAC address."

Ericsson came up with its suggestions by trying to match up with the metrics carriers already use. For the network's edge, carriers want to measure resource consumption per subscriber; the average revenue per user (ARPU) obsession is an obvious example. "If we can better isolate the cost of energy going to subscribers, then it helps put our product more in terms that their business is laid out in," says Baher.

In the metro, the currency of choice is the circuit, rather than full Ethernet capacity. "What you really want to know is: How many times can I slice it?" Baher notes.

The other problem with measuring raw capacity -- that is, the number of Watts per gigabit per second -- in the metro is that some systems' control planes max out before the Ethernet capacity does, "especially in systems that came more from the Layer 2 enterprise world," Baher says.

Ericsson, not surprisingly, is pretty happy with how the SmartEdge stacks up under the new metrics.

Table 1: How Green Art Thou?

One factor that comes into play is the age of an architecture. Newer designs, having been built to provide better specs than what's on the market, seem to come out with lower power numbers, as shown in these results measured for a typical edge-network service delivering voice, data, and video, and including subscriber management.

— Craig Matsumoto, West Coast Editor, Light Reading

Interested in learning more on this topic? Then come to Green Telecom East 2009: Transitioning to Environmentally Responsible Networks, a one-day conference designed to provide telecom executives with a concise summary of the latest infrastructure developments that will facilitate a global transition to environmentally responsible networks, to be staged in New York, June 17. For more information, or to register, click here.