Data travels across our national data “backbone” on fibre optic cable at 457 million mph. Provided that your local exchange has been upgraded, any bottleneck occurs from the exchange to the business premises. A number of acronyms describe the different methods used to carry the data between these two locations:
Digital Subscriber Lines (“DSL”) come in asymmetric (“ADSL”) and symmetrical (“SDSL”) versions. Asymmetric connections means you can download data faster than you can upload (send) data. As DSL uses existing copper telephone lines, premises which are are far from the local exchange will suffer slower speeds. Maximum speeds for ADSL are in the region of 1Mbps (upload) and 17Mbps (download) but typical speeds are much slower. In addition, DSL is a “contended” service meaning capacity is shared with other businesses and will reduce at peak times. DSL is relatively cheap as new cables are seldom required, but uploads are often too slow for reliable business use and repair times in the event of line failure can be prohibitive.
Ethernet First Mile (“EFM”)
Provided that the local exchange is EFM enabled, this technology can offer an inexpensive alternative to leased lines as it uses pre-existing copper cables. Installation is therefore relatively swift and inexpensive.
The name is not to be taken literally, but is a euphemistic reference to the distance between the business premises and the local exchange. Readers will be familiar with the high speed Ethernet networks in their offices – the same high-speed data connection can be established across copper telephone cables from the exchange to their premises. DSL broadband normally uses just one copper “pair” to deliver the service – EFM uses either two or four pairs which together form a symmetrical internet connection of up to 20Mbps. Multiple lines give resilience should one individual circuit fail, and EFM’s lower latency (data transit time) give an advantage for VoIP or video-conferencing tasks.
Fibre optic (BT Infinity)
This technology uses a fibre optic cable from the local exchange either to the green cabinet in the street near the business premises (“Fibre To The Cabinet” /“FTTC”) or all the way to the premises (“Fibre To The Premises”/“FTTP”). FFTP is obviously better than FTTC because the data travels on fibre optic cable for more of its journey. This is a contended asymmetric service offering download speeds of 76Mbps and upload speeds of up to 19Mbps, both of which may fall considerably at peak times.
The most expensive and robust option is a dedicated (not shared/”uncontended”) fibre optic data line direct to the business premises which can symmetrically send or receive data. Installation can be expensive, sometimes requiring groundworks to install cable – with consequent lead times. Users can specify different sizes of “pipe” from 2Mbps up to 10Gbps, then pay to use an amount of data capacity (“bandwidth”) up to their maximum “pipe” size. Data speeds are largely unaffected by the distance to the local exchange and data rates will be unaffected by other users.