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 Monday, June 18, 2007

An upgrade to a widely used specification for fibre optic cables will allow the simpler deployment of Gigabit Ethernet (GbE) in FTTH applications up to 500 m link distance. The original Recommendation ITU-T Rec G.651 provided specifications for multimode fibre which is currently widely deployed for data communications, but not for telecoms.

The work was initiated given two observations; the cost disparity between telecom and data networks, where high speed GbE telecom equipment is often far more expensive than datacom equipment; and the economics of rolling out FTTH into multi-tenant (apartment) buildings where there is a high subscriber density. Ethernet is increasingly seen as an end-to-end technology.

Similar to recently published Rec G.657 on single mode fibre, Recommendation G.651.1 allows for increased cable flexibility. This increased flexibility in a fibre optic cable means that operators can follow tighter corners in buildings and can worry less if cables / fibres are laid with a sharp bend. This all makes installation work more engineer friendly leading also to less re-work. Moreover the closures for fibres can be half the size, important where space is at a premium especially in multi-tenant buildings.

G.651.1 retains many of the key characteristics of its well known predecessor. However manufacturing tolerances and transmission characteristics have been improved significantly. In addition, it has been harmonized fully with relevant IEC standards.