Fibre networks: coming to a premises near you


With PC processor speeds rapidly increasing in line with Moore's Law, it should be no surprise that optical networking straight to the desktop is now on the agenda. However, there are various obstacles which still have to be overcome to make it a reality.

The market for optical premises networks is also an ill-defined market segment due to the recent arrival of the technologies that make such networks possible.

However, technical progress means that companies now have fibre standards that enable fibre-based systems to compete against established copper links. Also, blown fibre systems allow firms to increase the number of fibres they can use in response to business demands, using special ducting.

In addition, the industry now has the 10 Gigabit Ethernet protocol as an accepted standard. There is the promotion of a cheaper form of WDM using coarse wavelength division multiplexing (CWDM) that can be applied to the premises market in certain scenarios.

To further justify the advance of optical premises networks, on the business side there is the increased importance of storage area networking, data back-up demands, and an increase in electronic collaborative working in research and design, involving the shared access of much larger files. In some quarters there may also be the feeling that the days of copper are numbered, demonstrated by the slow progress being made to improve plain old Category 5 cable.

The possibilities in this market were dramatically demonstrated with this summer's announcement that Boeing was to spend USD20m developing an internal private optical network using technology and hardware from Nortel Networks.

Boeing's private national network in the USA will rely on dense wavelength division multiplexing (DWDM) and SONET to link its many offices in a giant wide-area network (WAN), and will see its engineers and designers being able to exchange large files within a heavily-guarded network.

Not every potential customer is the size of Boeing though. On a single site or campus, the level of activity in optical premises networks is just a trickle so far.

"Only in very limited and highly specific situations will companies currently deploy fibre all the way to the desktop," says Martin Van Schooten, EMEA marketing director at Extreme Networks.

"Most fibre implementations in the premises network run a fibre connection between campus buildings or in the riser between floors of a building to offer a higher, more scalable bandwidth connection for aggregated desktop connections, and to overcome some of the problems copper cable experiences with electrical grounding and interference."

Within individual structures, Van Schooten says Extreme is seeing buildings of over three storeys running fibre-optic cable in the riser connecting the floors and Category 5 cables running anything up to Gigabit Ethernet from the riser to the desktop.

For example, German-owned magazine publisher H Bauer uses hardware and multi-mode fibre from Extreme in the riser of its new offices in London, to aggregate the desktop connections into Gigabit Ethernet and enable the fast and reliable transfer of large publishing files.

Schooten believes that organisations running fibre to the desktop are those with problems with high levels of electrical interference such as power stations and factories, where running copper could result in packet-loss in mission critical scenarios.

Also he believes that companies using bandwidth-hungry electronic design applications, such as aviation and automotive manufacturers, would be ideal customers for full internal optical networks, an opinion which dovetails nicely with Boeing spending USD20m on such a network.

Schooten says Extreme has one aviation customer which regularly sees its desktops access files of around 500Gb or more. Using fibre gives them the reliability and network bandwidth to achieve this.

The military is also seen an ideal market for fibre backbones and fibre to the desktop, as a means of avoiding electrical interference and the threat of electro-magnetic pulses.

John Tinson, head of speciality at Brand Rex (Fig.2), which bills itself as Europe's second largest cable manufacturer and installer, acknowledges that there has been a lot of hype about optical connections direct to the desktop, and confirms such installations are few and far between.

However, on the military side, Brand Rex can point to a fibre to the desktop (FTTD) contract with the UK's Ministry of Defence (MOD) in London. The MOD is using Brand Rex's BloLite blown fibre to desktops as part of a modular approach to providing more reliable fibre links to help run the UK's military systems.

Molex Premise Networks is another cable supplier which sees the military as a key market for private optical networks, and says it too has signed contracts to support the UK military with FTTD, as well as other military bodies across Europe.

However, Molex will not give details of such jobs because of secrecy demanded by its customers. More typical of its optical fibre customer portfolio is a contract to support the newly opened Worcestershire Hospital in England.

This sees 5km of fibre combined with 300km of copper linking 4,800 access points, with the installation designed to deliver Gigabit Ethernet speeds to desktops using the new Category 5e (Category 5 enhanced) copper.

Gigabit Ethernet over copper was a much talked-about solution at the end of 1990s. But it is only now that the technology is being widely used, thanks to Category 5e. Gigabit Ethernet is possible over plain Category 5, but connection distances are reduced and there is more chance of technical problems.

Category 6 copper is also supposedly now with us after approval by the relevant standards bodies. So it may be some time before customers and suppliers alike start to see an immediate reason to choose fibre for everything, if they can now already enjoy Gigabit Ethernet with Category 5e and even faster speeds with Category 6. And, of course, optical Ethernet hardware is also more expensive.

The cost of optical components is cited as an obstacle by Trescray Network Communications, which is particularly active in the financial sector as well as the carrier market. But Trescray chief executive Matt Flowerday told Lightwave Europe, "A fibre network may be more expensive than one based on copper but, as voice over IP and video over IP technology becomes widespread, there will be an increasing need for high bandwidth to the desktop."

As well as supplying copper and traditional fibre systems, Trescray also supplies blown fibre systems. Flowerday recommends that users who are unsure about their future bandwidth requirements should use such a system and install the necessary ducts during their next major network overhaul.

Users can then call back the supplier when they want extra fibre connections blown through to meet demand. One Trescray customer which has recently decided to adopt blown fibre is the Natural History Museum in London.

A particular area of a company that may want to consider fibre is the data centre, as a result of the huge increase in data now carried and stored by organisations. Such demands also apply to companies which have outsourced much of their storage and back-up systems to an outside contractor, and who don't have their own fully fledged data centres.

Once stored data is needed by specific users on an internal LAN, the external connection to the data bank is obviously critical, but the transfer of the data across the LAN can prove crippling to overall bandwidth availability on corporate networks that are not built on fibre.

The market for optical premises networks is currently seeing a mix-and-match approach being taken by customers and suppliers alike, as a result of both technical issues and basic price factors. However, end-users are definitely forming into something resembling a large potential business opportunity for the optical market.

Antony Savvas
LWE Contributing Editor,
and Networks and Telecoms writer

Antony Savvas is a freelance networks & telecoms writer. Email:

The standard topology for optical premises networks is a fibre backbone with copper used to the desktops. This is often known as a distributed topology.

If fibre is used for both areas, the user should be aware that there can still be a huge amount of networking equipment running on copper which still needs to be supported.

To supply fibre to the desktop, a centralised topology can be used. This sees the fibre extended from the work location through the telecoms room and terminated in a central location where all the data networking kit is housed.

The maximum distance supported is 300m, which can accommodate up to 92% of existing buildings.

The big question is what type of fibre to deploy in the backbone or for horizontal cabling to the desk. Future local area networking will need 10Gbit/s in the backbone and at least 1Gbit/s to the desk.

Gigabit networking equipment using vertical cavity surface emitting lasers (VCSEL) operating at 850nm would be more economical than that using conventional lasers operating at 1300nm. For this reason, the use of 50/125µm fibre over 62.5/125µm is preferred for new installations. (Source: Nordx/CDT)

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