Fibre fact-finding expedition
I’m not an engineer, I just help out running Connecting Shropshire’s social media accounts. So, to help me gain an understanding of what they do, the Connecting Shropshire team sent me out for a road trip with Openreach to see a little more about the nuts and bolts of how this whole fibre internet thing works. So, here it is, from the engineers through me to you.
My guide for the day from Openreach, Mike Gardiner, leads the way. First up I was taken to the ‘frontline’ and visited an engineer putting the finishing touches to one of the shiny new cabinets.
“This road-side cabinet is what we engineers call the D-SLAM,” Mike announces, rather less grandly than I’d envisaged, while opening up the cabinet. For those not versed in technical speak (me included), D-SLAM stands for ‘Digital Subscriber Line Access Multiplexer’. Nope, me neither. I bravely swallow my pride and ask what it means. Luckily, it seems it’s not the first time someone has asked. It’s because, in the telecoms industry, a fibre customer is a ‘Digital subscriber’. The cables connecting these ‘Digital Subscribers’ to the network are the ‘lines’ and ‘Digital Subscribers’ need their ‘lines’ to get ‘access’ to the network though the cabinet. ‘Multiplexer’ means that more than one line, or customer, can use the fibre at the same time. After jotting my new learnings down, I look for more information.
How long does it take to set up a cabinet like this?
“I’ve been working on this one about three hours this morning, we had already pulled the cable into the footway box, which is around 10 metres away and I’ve just been pulling the remainder of the cable in. This cabinet has not been as straightforward to install as I would have hoped.” Mike pauses for a second, then continues.
“The problem we’ve had with this particular cabinet has been with the duct between the fibre optic cabinet and the old copper cabinet just down the road. The ducts connecting the two were badly blocked, you see. Our ducts often get filled up with silt, or get damaged by tree roots and the like. In this case, we had to excavate the pavement around the duct and then repair the duct. Only then could we pull the cables through and connect them up. This is just one part of the job, each cabinet involves hundreds of hours of work on average.”
Wow, I feel like Paxman or something. What a question that was. I press on, eager to show I’m one of them really, and hit them with another tough question.
So how does it all work then?
“So the fibre comes to the new D-SLAM from the nearest large exchange or ‘head end’. You get the phone line that comes into the existing cabinet from the local telephone exchange and then off to the customer.” Mike explains. I understand, perhaps I’m actually really technologically minded but just hadn’t realised until now…
“So,” Mike continues, snapping me out of my dreams of being the next Tommy Telford chap. “when someone here in Shropshire decides to upgrade to fibre broadband, an engineer would come along, the phone line gets disconnected in the old cabinet then gets re-diverted into the D-SLAM. It goes in one side, the magic side as I call it, and comes back out, gets linked back to the old cabinet and then out to customer as fibre broadband.”
I nod encouragingly, quickly realising I may not be the undiscovered engineering genius I thought I was about 10 or 15 seconds ago.
“This D-SLAM extends the exchange equipment so that it’s closer to homes and businesses…it might be easier if I got a piece of paper and drew it for you!”
I fear he’s picked up my shortcomings. Thankfully, he does just that and, like a child with a picture book encyclopaedia, I suddenly find things easier to understand and realise it’s not actually as complicated as I thought.
Here is the full version of the diagram he drew for me:
So, the fibre runs from the head end exchange all the way to the new roadside cabinets, connected through a series of ducts. The copper line comes from the telephone exchange, into the old copper cabinets nearby. The two cabinets are connected using copper wire, and the existing copper line runs from the old cabinet into nearby homes and businesses. So when you contact your chosen Internet Service Provider to order an upgrade from copper broadband to faster fibre (and you can choose from a number of service providers), the changeover connects you to the fibre cabinet, meaning the data moves from the head end exchange to the cabinets through the fibre network, not the copper one, and then out to the homes down the copper line giving you faster internet. Fibre to the Cabinet is a bit like if you are running a marathon, but for the first 26 miles you get a taxi and only run the last few hundred yards, making your average speed much faster.
Sadly, I had to be whisked away at this point but I was left with a promise that my education would continue soon with a trip to the head end exchange. Sounds exciting. But for now, this is where my teaching ended.