A technical group working on the next generation of Ethernet has agreed to disagree and will now work on a single standard that covers both 40Gbps (bit-per-second) and 100Gbps speeds.

The Higher Speed Study Group (HSSG), part of the IEEE (Institute of Electrical and Electronics Engineers), made the decision last week at its meeting in San Francisco after months of debate between backers of the two speeds. If the IEEE approves the move late this year as expected, a standard may be completed by mid-2010, said John D'Ambrosia, chair of the HSSG.

Ethernet has sped up by a multiple of ten several times, from 10Mbps to 100Mbps and ultimately from 1Gbps to 10 Gbps, the current fastest version. Some HSSG members backed a similar boost this time and that 100Gbps plan appeared to have won out late last year. But others pushed for a 40Gbps standard.

Different applications were at the heart of the disagreement, according to D'Ambrosia. The need for speed is growing everywhere, but at different rates. While the data output of servers doubles roughly every 24 months, the amount of traffic on carrier networks is doubling every 18 months, according to D'Ambrosia. Members more interested in faster server-to-switch applications pushed for a 40Gbps goal, while those aiming at network aggregation and backbones favoured 100Gbps. The higher speed means more expensive and power-hungry equipment.

"I wouldn't say there was a fight. I would say there was an education going on and it got heated at times," D'Ambrosia said.

Now a single standard, to be called IEEE 802.3ba, will include specifications for both speeds. Each will offer a selection of physical interfaces: There will be specifications for 40Gbps links up to one metre long for switch backplanes, 10 metres for copper cable and 100 metres for multimode fibre. For 100Gbps, the group will standardize 10-metre copper links, 100-metre multimode fibre links and 10-kilometre and 40-kilometre distances on single-mode fibre.

It's the first time an Ethernet standards task group has pursued two speeds in one standard, according to D'Ambrosia. "One size doesn't fit all, in this case," he said.