Calix unveils 2.5-Gbit/sec GPON ONTs, announces GPON milestone

SEPTEMBER 24, 2007 By Meghan Fuller -- Calix (search for Calix) today introduced its 700G Series GPON (search for GPON) optical network terminals (ONT), which it claims yields all the bandwidth and operating efficiency of PON technology while delivering a Gigabit Ethernet interface to the customer.

According to the company, the only physical difference between the 700G (where the "G" stands for the Gigabit Ethernet subscriber-side interface) and Calix's previously announced ITU G.984-compliant 700 Series GPON ONTs is that subscriber interface, which now supports 10/100/1000 Base-T Gigabit Ethernet.

While a Gigabit Ethernet might seem kind of "ho-hum" to a Lightwave audience contemplating speeds of 40 Gbits/sec and even 100 Gbits/sec in the wide area network, says Calix vice president of corporate marketing Kevin Walsh, "most Americans today are still operating at 3- to 5 Mbits/sec, so this is an enormous leap forward in terms of the amount of bandwidth that can de delivered to the home."

Beyond the residential application, the Gigabit Ethernet subscriber-side interface makes the 700G ONT ideal for use in business applications to deliver bandwidth increments of 50- or 100 Mbits/sec.

But the folks at Calix are more excited about the ways in which 2.5-Gbit/sec GPON better positions the telcos in their battle with the cable multiple service operators (MSOs). In some ways, says Walsh, this is a battle between service providers, but in many other ways, it comes down to a battle between two key technologies: 2.5-Gbit/sec GPON and DOCSIS 3.0.

DOCSIS 3.0 technology allows for the bonding of up to four QAM channels to produce 160 Mbits/sec downstream and 120 Mbits/sec upstream. Calix says its new 2.5-Gbit/sec GPON ONT with Gigabit Ethernet subscriber-side interface, by contrast, offers a peak downstream rate of 1-Gbit/sec and 1 Gbit/sec upstream. Measured in terms of average or sustained bandwidth--which is a more relevant comparison, they say--GPON provides 80 Mbits/sec per subscriber in typical 32-household configurations versus DOCSIS' 640 Kbits/sec.

Walsh reports that he has spoken with a number of people regarding this bandwidth disparity, and several people have assumed it was a miscalculation. When asked why, he notes that "people just aren't used to seeing kilobytes anymore. We've graduated into Megabytes and Gigabytes, and now we're looking at Petabytes and Exabytes," he says. "But if you do the math with DOCSIS 3.0, because it is a shared medium, you have 160 Mbits/sec divided over the size of the node. In the case, we're using 250 [households per node]. That's a simple math problem, and it yields 640 Kilobits, on average, of bandwidth that they are delivering to the household."

"The bottom line here is that DOCSIS remains a copper-based technology," adds Ray Savona, vice president of field marketing at Calix. "In essence, it's fiber-to-the-node with an HFC plant, but rather than using VDSL for the drop, you're using DOCSIS on coax versus a twisted pair."

For their part, Walsh and Savona admit that the Calix 700G ONT would be a perfect fit for the cable MSOs as well. It has an RF band in which they could put their channel line up; it would solve a lot of the problems associated with delivering bigger IP streams; and it would be compatible with their current set-top boxes. The pair confirms that Calix has had conversations with a number of small cable operators.

"It will be interesting to see if this becomes a more prevalent trend," says Walsh.

The GPON 700G Series

The 700G 2.5-Gbit/sec GPON ONT began shipping in July and is now generally available.

Configuration options for the 700G include: