SPECIAL FEATURE fibre optic & copper cabling
ToR v EoR
Top-of-Rack ( ToR )
Less cabling , more switches Server connection using short patchcord ( Cu or FO ) Risk of oversubscription , more unused ports Higher upgrade cost
End-of-Row ( EoR )
More cabling , fewer switches Server connection using copper structured cabling Lower upgrade costs
Distances are usually less than 30m , allowing Category 8 to be used to provide an upgrade path . In this case , copper uplinks can provide a cost-effective and energy saving solution . Switches can be upgraded from 1G to 10G to 25G to 40G without the need to re-cable . A ‘ Middle of Row ’ solution can be interesting with copper over 30 meters .
Another consideration : in ToR you typically have 32-48 downlink ports per server rack . In practice , you need an average of , say , 24 ports per rack . That means an unused port overhead ranging from 25 % to as much as 50 %. Using an End of Row design avoids this . Switches with more ports may be allocated and a far higher port utilisation of some 90 % can be reached . EoR switches can use fewer ports , saving on hardware costs and power .
Further considerations
Copper terminations are largely standardised , which translates to relatively consistent pricing levels . On the other hand , there are many types of fibre connectors with varying price levels . The arrival of small form factor connectors is bringing down the costs of installations .
It can be difficult to predict the volume of cabling required during the lifetime of a facility and using fibre can theoretically reduce the impact of this . Installing fibre can be relatively fast and straightforward – but only in installations where a great deal of the work can be standardised , with pre-built patches and where there ’ s sufficient field installation expertise on hand . When there ’ s field splicing and patching involved , the costs and time investment can increase rapidly .
As our society and economy become increasingly mobile , digital and smart , the cabling that needs to connect increasingly powerful servers and storage systems needs to be robust , flexible and scalable . It must be able to adapt to new requirements , support consecutive generations of active equipment and allow connection of more and more bandwidth and ports . Reducing risk and hassle in the field means significant savings on time and cost .
When deciding to use copper or fibre on a certain part of a network , there are a multitude of factors to consider . What ’ s more , not all fibre and copper types are identical . It makes sense to select a cabling solution that will support current network requirements and offers enough scope for later expansion without under , or over specifying . When in doubt , don ’ t hesitate to consult an expert !
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