Is there room for an intermediate step between Gig and 10Gig Ethernet? Force10 Networks hopes so - it is announcing what it says is the industry's first high density 16-port 10Gig Ethernet line card, and it hopes to use this to open a mass market for 10Gig.

The card slots into Force10's TeraScale E1200 and E6000 switch chassis (there's a companion 8-port version for its smaller E300 model) and it allows the E1200 to provide 224 ports per system, way more than any of its rivals, claimed the company. There is a catch though - the card is over-subscribed by around 4:1, so if all 16 ports are driven simultaneously they will only get perhaps 2.5Gbit/s each.

It's a matter of recognising that not everyone needs or can afford the line-rate gear used by the likes of CERN, claimed Steve Garrison, Force10's corporate marketing VP. He said that the new cards list for $57,500, which should translate to a street price of under $3000 per port.

Is $3000 cheap enough to justify mass migration from Gig Ethernet? Probably not - Gig ports are $500 to $600, and Garrison admitted that a 5x or 6x premium is still too high, based on past experience. "It was 4:1 for Fast Ethernet to Gig migration," he said. "We will be there in late 2007 or 2008 for 10Gig, if you map out the price transitions."

In the meantime though, he argues that 10Gig is becoming cost effective for many data centre uses. He claimed that most of today's links rarely exceed two or four aggregated Gig links anyway - and anyone needing line-rate 10Gig can still get a four-port TeraScale card which offers that.

"We are giving people more data centre options," he said. "We see an emerging market for 2-3Gigabits per port, with pricing closer to Gigabit. Early adopters want line-rate but the mass market does cost trade-offs and price-per-port trending."

The limiting factor is Force10's current ASIC technology, which restricts each chassis slot to 48Gbit/s of bandwidth. However, Garrison said that the physical backplane can handle more than 160Gbit/s per slot, and new ASIC technology under development will allow the company to offer a system with 224 10Gig ports, all running at line rate, in two to three years time.

This is important because it means customers won't need to upgrade the chassis, just the cards, he said, adding: "People depreciate line cards over three years, but chassis over five to seven, or even ten years."

The 16-port line cards use the 10Gig Ethernet Small Form Factor (XFP) standard connector for optical components, and are scheduled to be available on 15 Dec.