A CASE FOR FIBRE … OR IS IT?

From NetworkComputing Magazine Vol 18 Issue 01 - January/February 2009

MIKE HOLMES OF CABLING SOLUTIONS COMPANY NEXANS, RISES
ABOVE THE COPPER VERSUS GLASS ARGUMENT AND FOCUSES ON
BEST APPLICATION

Copper or fibre - the debate has been raging for as long as 10 Gigabit Ethernet fibre optic solutions have been available, but it is by no means over yet. In the world of data centres strong support for the fibre option is generally found and it is growing, but it is equally clear that copper has not lost any of its attraction in the traditional office setting. The essential values of each within their broader fields of application have to be understood in order to enable users to make informed choices.

The debate is not entirely about whether copper or fibre is better, but rather where and when to use each to achieve the best results. For example, in office surroundings requiring less than 10G Ethernet, copper cabling is generally used, but when speeds of 10G Ethernet or higher are required, suppliers and users need to evaluate all the pros and cons of the options in the marketplace. And we now see 40G and even 100G proposed as the next technology steps.

SPEED AND DISTANCE

Generally speaking, fibre outperforms copper over the distance and high-speed stakes. Initial claims suggested fibre would have the capacity to carry almost infinite bandwidth over inconceivable distances, but the truth appears to be more conservative. Multimode fibre now looks as though it only

A CASE FOR FIBRE … OR IS IT?

MIKE HOLMES OF CABLING SOLUTIONS COMPANY NEXANS, RISES ABOVE THE COPPER VERSUS GLASS ARGUMENT AND FOCUSES ON

outperforms copper by two or three times over distance.

However, research and technological innovation have enabled copper to support higher bandwidths, because of improvements in standardised cables and connectors (RJ45 and GG45). This secured its place as the dominant LAN media over shorter distances (up to 100 metres) for the foreseeable future - especially where demand for speed is a lesser factor than the costs of going faster. Cat 7 is shown as having potential capability to support 40G over 100m or even 100G up to around 40m.

Copper's further benefit is that it provides power over the Ethernet (PoE) to remote devices such as cameras, controllers and sensors. Additionally, sites requiring outlets beyond the 100 metre limit will need copper systems which offer an extended transmission distance. Fibre is typically better suited for external use.

THE QUESTION OF COST

Copper has always enjoyed a significant cost advantage over fibre. The cost of a fibre optic network with cabling and active equipment is significantly higher than that of its copper equivalent. This differential will gradually improve as VCSEL (Vertical Cavity Surface Emitting Laser) technology will reduce active fibre transmission costs through the replacement of expensive lasers.

Copper's quest to remain competitive with fibre in terms of bandwidth, has led to the development of larger and bulkier

BEST APPLICATION

unscreened (UTP) cables to meet the Cat 6a standard for 10G. This has the disadvantage that it is relatively more difficult to install and uses more space; an important consideration in data centres. As a result, screened cabling has been increasingly adopted for 10G applications as it is typically 10 to 15% smaller in diameter and easier to install.

EASE OF INSTALLATION

Installation costs account for approximately 60% of the full investment in cabling projects. In this domain copper has an advantage over fibre because mounting its connectors is easier in contrast to fibre, which has a larger variety of connectors and fewer experts to guide installers through fibre-related challenges.

Fibre, however, gets the approval from a green perspective because it delivers reduced power consumption in comparison with copper. However recent developments within the Energy Efficient Ethernet 802.3az working group have led to lower powered PHY (physical layer connection) devices for copper; again reducing the differential.

THE FUTURE

While the future appears to favour fibre in new environments like data centres, copper retains its place in the typical office environment. However, it would seem that each option, fibre, copper and - indeed wireless, have a distinct role to play in the LAN environment. In the end, it is up to users and their suppliers to do the necessary research for their specific applications, before determining the best solution. NC