GPON Interops

By Jonathan Tombes

The Full Service Access Network (FSAN) held its seventh GPON interoperability test event in late October, drawing a dozen vendors of optical line termination (OLT) and optical network termination (ONT) equipment together to focus on GPON's ONT management control interface (OMCI).

(For a quick overview of the different flavors of PON, click here. For a look at Verizon's iteration of PON and its competitive vulnerabilities, click here.)

Who is the FSAN? The list of telco operator members is a tip off for why GPON remains relatively alien to cable MSOs. The FSAN website lists more than 40 vendor members. (See the lists below for operator members and interop vendor participants.)

This latest test event was hosted by New Jersey-based Telcordia and included the cooperation of Corning Cable Systems and TraceSpan Communications, developer of a GPON protocol analyzer.

"We were the first independent test lab to be invited into FSAN in 2004," said Rob Bond, senior systems engineer at Telcordia. "We hosted the first test event, back in January 2006."

Bond said testing has roughly followed the open systems interconnection (OSI) model, focusing initially on the physical layer and gradually working up into the ONT management and control interface (OMCI). One outcome of recent tests has been the creation of an OMCI best-practices implementer's guide, which FSAN members plan to pass along for consent at the ITU-T study group (SG) 15 plenary meeting in December.

ITU-T SG 15 is the standards body responsible for the G.984 GPON standard.

"As often happens with standards, OMCI was written with a lot of compromises and flexibilities," Bond said. "When it come to interoperability, that presents problems."

The next FSAN interop, also geared toward OMCI, is slated to occur next summer in Nice, France. Representatives of France Telecom and Telecom Italia serve as co-chairs of the Interop Task Group.

As for how much GPON interoperability exists in practice, apart from the lab, Bond admitted that operators at this point tend toward single vendors.

According to another GPON observer, ONT developer TXP is one of the only vendors currently interoperating with multiple vendors' OLTs. TXP, which has agreed to merge with Cambridge Industry Group (CIG), acquired its ONT assets from Siemens AG in 2006.

New pieces added to PON over the past year include G.984.5, which defines a wavelength plan that could coexist with so-called next generation (NG) PON; and G.984.6, which specifies a GPON extender.

"It's basically a standalone box that sits between the OLT and splitter," said Bond. "It allows you to extend the reach of the customer location up to 60 km."

The standard allows for both an optical amplifier and an optical-electrical-optical (OEO) repeater; an additional document addresses how to manage this device.

GPON standards development will continue moving into service provisioning in 2009, Bond added, with some operators interested in using both CMCI and the Broadband Forum's TR69 model.

Vendor Participants in 7th FSAN GPON Interop

Alcatel-Lucent
BroadLight
CIG*
Conexant
Freescale
Hitachi
Huawei
Ikanos
Motorola
PMC-Sierra
RAD Data
TXP Corp*
ZTE

* In merger talks

FSAN Operator Members

• AT&T Labs
• Bell Canada
• Bharat Sanchar Nigam Ltd. (BSNL) (India)
• BT Group (UK)
• China Telecom
• Chunghwa Telecom (Taiwan)
• Etisalat (United Arab Emirates)
• France Telecom
• KT Corporation (Korea)
• Nippon Telegraph and Telephone (Japan)
• SaskTel (Canada)
• SingTel (Singapore Telecommunications)
• Sprint Nextel
• Telecom Italia Group
• Telus Corporation (Canada)

- Jonathan Tombes

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