fibre optic & copper cabling
SPECIAL FEATURE
Copper or fibre : making smart choices
When specifying , building or upgrading networks , you ’ ll always need to choose between copper and fibre cabling . However , there ’ s no need to pick one over the other for the entire project . How do you make the best choice for each part ? Martin Roßbach , director of product marketing and new market development at Nexans Cabling Solutions , explains .
Well-designed networks mix copper and fibre , striking a perfect balance between performance requirements , ports , bandwidth and practical considerations . Let ’ s first look at a few traditional pros and cons of both copper and fibre cabling – and tackle some myths in the process .
A few facts – and misconceptions
When is copper the smart choice ? Copper is particularly reliable and generally seen as easier to install and terminate than fibre cables . Traditional ‘ category ’ copper cables have a 90-meter distance limitation , making them suitable for in-building applications . Fibre , on the other hand , generally offers higher bandwidth than copper and suffers less from attenuation loss , allowing higher bandwidth to be retained over greater distances . In addition , fibre is dielectric ( nonconductive ) and therefore immune to external electromagnetic interference ( EMI ) caused by electrical and magnetic fields . Although copper can be sensitive to this interference , recent generations of shielded copper cables exceed critical parameters significantly . This ensures reliable transmission whilst reducing onsite testing time .
Considering cost
Making a direct comparison on price between fibre and copper is tricky as there ’ s much more to be considered than simply the price of the cabling itself . The cost of active equipment needs to be factored in , as a 10G copper switch costs less than a 10G fibre switch . In many cases , the most cost-effective solution will be determined by the specific requirement and take into consideration bandwidth , distance , the infrastructure design and volume of connections .
In Data Centres
In today ’ s fast expanding and changing data centres , space is at a premium . Typically this gives fibre an advantage due to the small cable dimensions and small form factors , but with highdensity racks featuring vertical cable management and angled panels , large volumes of copper cables can also be accommodated – typically up to 1,000 cables on a 45U patch rack .
The idea is commonly held that only optical fibre can handle higher data rates . Copper cabling categories up to Category 6A are designed for rates up to 10G over 100m , but latest generations of Ethernet for twisted pair , which will support 25G over Cat 7A or 40G over Cat 8 , are limited to 30m . However , that ’ s not an issue for most practical applications in the data centre . Server rows are generally under 30 metres in length and links in and between cabinets are no more than five metres . As Cat 8 cable is specified up to 2 GHz it can accommodate 40GBase-T – at a potentially attractive price point .
Copper , fibre and DC architecture options
Today , combined copper and fibre solutions for different design options – End of Row ( EoR ), Middle of Row ( MoR ) and Top of Rack ( ToR ) – can bring design flexibility , performance optimisation and , in many cases , considerable cost savings . Delays in the development of 10GBase-T opened the door for ‘ Top of Rack ’ as an easy way to implement DC networking . Traditionally , ToR switch-to-switch connections with their need for speeds of up to 100 Gb / s are mainly fibre . With line speeds above 10G , the reach of copper was limited to 5-8m . However , ToR isn ’ t particularly configurable or energy-efficient .
The latest generation of Category 7A or Category 8 copper can be used as part of a ToR configuration , for example in switch-to-server downlinks , which require lower speeds . 25G and 40G can be supported intra-row ( within a 30m range ) providing an upgrade path for switches without recabling .
End of Row ( EoR ) switching is more energy efficient and can reduce the number of switch ports required .
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