Salira Prompts PON Questions
The news fuels a growing debate about the merits of EPONs compared with today's PON products, which are overwhelmingly based on Asynchronous Transfer Mode (ATM) (and are thus known as "APONs"). It also raises questions about the potential of the PON market in general.
PON gear, which deploys passive splitters to siphon optical bandwidth among multiple users, can be based on a range of technologies. Salira, which debuted last year (see Salira Eyes Ethernet Access), is one of a handful of startups claiming Ethernet offers a faster, cheaper, and more efficient basis for PONs than ATM does. Another EPON maker is Alloptic Inc. (see Alloptic Pushes PON Scheme).
Do EPON claims hold up? Salira says its gear is substantially faster and denser than equipment from PON vendors like Optical Solutions Inc. and Quantum Bridge Communications Inc.. Salira also claims its EPON enhancements rival Alloptic's. On the face of it, the claims seem valid:
Table 1: PONs Compared
|Vendor||PON Type||Speeds to 20 km||PON endpoints per chassis||Backplane speed|
|Alloptic||EPON||1 Gbit/s downstream; 900 Mbit/s upstream||512||16 Gbit/s|
|Optical Solutions||APON||330 Mbit/s symmetrical||1,152||Not applicable for data; about 1 Gbit/s for voice|
|Quantum Bridge||APON||622 Mbit/s symmetrical||192||5 Gbit/s|
|Salira||EPON||1 Gbit/s symmetrical||5,376||Not applicable|
Salira's extra megabits should come in handy. Since PON bandwidth is shared among users, any extra capacity is a boon. But analysts warn that speed alone won't sell PONs. "Ethernet technology in and of itself is not an advantage for PON," says Barry Moon, senior analyst at RHK Inc. If it were, Ethernet connectivity services wouldn't be bankrupt, he says. Moon and others say PONs won't sell until fiber itself becomes more plentiful.
Other advantages claimed by Salira seem less obvious. Salira claims its EPON design enables it to shunt POTS (plain old telephone service) voice traffic and leased lines in native formats, eliminating the need to convert data to ATM before moving it over the PON. Also, Salira credits its Ethernet base for QOS (quality of service) control that lets carriers allocate bandwidth down to the per-subscriber level and create various classes of guaranteed Internet Protocol (IP) service in PONs.
But other vendors -- including all EPON and APON suppliers mentioned in this article -- claim to have per-subscriber bandwidth and QOS control in their wares, too. And they say carriers don't care about ATM conversions inside a box, as long as the unit has the interfaces to hook to the right kinds of services, such as POTS and T1 (1.544 Mbit/s) leased lines.
Bottom line? It looks as if Salira's gear may be faster and denser than what's out there today, but other features remain unproven. General delivery of Salira's gear isn't set until the third quarter of this year, and there are no customers yet.
Salira may face an extra challenge in winning those customers. It's gunning for enterprise service providers, not the prime PON market of fiber to the home (FTTH -- see Fiber to Home: Dream Deferred? and PONs Hit the Big Time). RBOCs, the prime movers of business services in key metro areas, aren't buying PONs in any quantity, and what they're willing to try is based on the ATM FSAN (Full Service Access Network) specs approved two years ago by the International Telecommunication Union, Standardization Sector (ITU-T). While EPON specs are being addressed by a working group of the Institute of Electrical and Electronics Engineers Inc. (IEEE), that group doesn't cut it with RBOCs as the carrier-centric ITU-T does.
Most sources think the market for PONs will support both ATM and Ethernet gear until one proves out the other in live deployments. "Our take is that [ATM] PONs will dominate the market for the next three to five years," says Darryl Ponder, CEO of Optical Solutions. "Ethernet will start to take over after that. The game will be won or lost on the cost of deployment."
Meantime, Salira's news gives observers a chance to take the general pulse of the PON market, which continues its bumpy takeoff. Despite the high-profile abandonment of PONs by Marconi PLC (Nasdaq/London: MONI) earlier this year (see Marconi to 'Streamline' Access ), there is some news. Here are some recent highlights:
- EPON vendor Alloptic has made substantial progress worldwide, according to Burnie Atterbury, Alloptic's senior director of product marketing. "We're in trials with every major PTT. We're extremely active in Canada and Asia," he says. A key selling factor, he claims, is that Alloptic offers one platform for both FTTH and business PONs. (Salira says it will equip a new box for home services at an unspecified future date.) Alloptic, which will be showing its wares in the Extreme Networks Inc. (Nasdaq: EXTR) booth at Supercomm, is also on the verge of closing a new round of funding, Atterbury says. While terms are still secret, the vendor has already raised $54 million.
- Optical Solutions is forging partnerships with IP television vendors in order to offer more options to carriers seeking PONs for FTTH services. The vendor announced a partnership with Minerva Networks Inc., and the two will show their integrated wares in Atlanta (see Optical Solutions, Minerva Hawk FTTH). Optical Solutions says another IP TV partnership announcement is imminent. The vendor recently announced a new funding round (see Optical Solutions Gets $22M).
- Quantum Bridge has teamed with Carrier Access Corp. to offer a digital loop carrier with PON capabilities (see Duo Collaborates on PON). The vendor also concedes that it raised another $40 million late in 2001, bringing its funding total to about $150 million so far. A spokesman says the company simply chose not to announce the round, in which previous investors participated. But in hindsight, it looks as if the funding may have coincided with layoffs and the withdrawal of the company's IPO (see Boston Area Startups Slash Jobs) -- hardly an auspicious time to tout new funding.
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