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Ofcom, Openreach and Dark Fibre

Those who have been following the design, build, and transition of the JAP will be acutely aware of the complexities of building such a network and some of the choices we’ve been forced to make due to the lack of ubiquitous dark fibre. There is, however, some light on the horizon…

Ofcom is the regulator for communications in the UK covering both the post office and telecoms. Their job is to ensure a fair and equal market exists across the communications sectors they are responsible for, and they regularly review each of them to make sure all is well in the world.

Openreach is a wholly-owned subsidiary of BT Group tasked with providing much of the telecoms infrastructure in the UK. Jisc buys several different services directly from Openreach to provide services for members and customers.

Dark-fibre (DF) is basically unlit fibre optic cable that various organisations lease from telecoms companies, the company buying the fibre is then able to use whatever equipment they want to provide service to the end-users across that fibre. Jisc buys DF from a range of suppliers, but until recently not from Openreach not because we didn’t want to, but because they wouldn’t sell it to anyone.

When building new pieces of infrastructure for Janet, the default situation is to look for a DF-based solution to provide the greatest flexibility in the hardware we attach to that infrastructure.

However, DF isn’t universally available to purchase (there may be fibre in the ground but there is no way for us to lease it) and so we fall back onto a ‘spectrum’ service from Openreach called Optical Spectrum Access Filter Connect (OSA FC) which is a lit service that does give a limited amount of flexibility in terms of hardware (but costs more annually) as we connect directly to the optical filter and use a mandated list of grid slots at whatever bandwidth we can fit into those slots.

Following one of the regular market reviews, Ofcom is requiring that Openreach provide DF in areas where there is no competition. We’ve already started to use the inter-exchange variant (called DFX) in locations where it fulfils the needs of the JAP build but this direction will allow Jisc to use the access variant (called DFA) to get from the exchange to the end-user site.

That does mean that in future your access circuit could be provided by Openreach as DF allowing Jisc to connect you to Janet at higher speeds more cost-effectively rather than the more restrictive Ethernet or Optical Access products that Openreach currently sell.

The only challenge here is that Ofcom’s definition of “competitive” does rather limit the scope and availability but it’s a step in the right direction. For more details, you can read all the lovely papers over at the Ofcom website


By James Blessing, post date 11th May 2021

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