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Who's Growing a GPON?: Page 2 of 3

For the uninitiated, here's a thumbnail tutorial in terms:

  • BPON is the same as an APON (ATM PON), with extra overlay capabilities for broadband services like video. APON is the PON transmission technique based on Asynchronous Transfer Mode (ATM) signaling that was developed by a group of carriers as part of the Full Service Access Network (FSAN) in the nineties. BPON is approved as International Telecommunication Union (ITU) spec G.983x. It supports data rates to 622 Mbit/s out to an endpoint (upstream) and back from the customer to the service provider's remote aggregation point (downstream).
  • GPON uses a different, faster approach (up to 2.5 Gbit/s in current products), encapsulating traffic in a version of the Sonet-compatible Generic Framing Protocol (GFP). GPON is on track to becoming the ITU's G.984x. Final pieces are expected to be put in place at meetings in August and October 2003.
  • EPON stands for Ethernet PON, which, as its name indicates, is a technique that uses Ethernet as the main transmission method for the PON. EPON runs at gigabit rates and has its own standarization process underway at the Institute of Electrical and Electronics Engineers Inc. (IEEE).

GPON fans claim its star is rising. Its blazing speed would make it ideal for "triple play" suites of voice, video, and data services from ILECs and other carriers. In contrast, other forms of PON don't have the bandwidth or multiprotocol support to do that. Its use of Sonet framing enables providers to link native TDM and voice connections into the PON without adding Internet Protocol (IP), making it more efficient than EPON.

Of course, for their part, EPON vendors such as Alloptic Inc. have much to say on the relative merits of their approach (see Chip Startups Bank on EPON and Alloptic Delivers FTTP in Wash.), particularly in keeping down the cost of fiber-to-the-home PONs.

So far, the only vendor that's shipped a GPON product is FlexLight Networks, which says its Optimate PON runs at 2.5 Gbit/s downstream and 1.25 Gbit/s upstream (see Giga-PON Ships Quietly). Flexlight hasn't announced any customers, though the box is said to be in trials at France Telecom SA (NYSE: FTE).

Flexlight's CEO, Gary Lee, says he expects competition to emerge fairly soon, mainly because there's so much interest in replacing private lines in metro networks with faster Ethernet services -- such as ones that extend storage area networks (SANs) from site to site via IP. GPON can also start replacing Sonet rings, Lee says.