Carrier telephony books

Hi All,

I had a quick search on the boards and I couldn't find any previous questions about this. Does anyone have some very basic but good recommended books about carrier technologies and general telco jargon?

We are having loads of private wires installed for some traders at the moment and although im not completely lost on everything I would like to know the basics when they start telling me about the DP's and how the exchange infrastructure works.

Thanks in advance if anyone has any good resources.

Pash

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Pash

Telecom Dictionary, PSTN, PBX, Datacom, Broadband, IP Telephony and IPTV: Amazon.co.uk: Lawrence, Harte: Books

Well this might look ok to me because it has diagrams and photos! anyone have this?

wirerat

Newton's Telecom Dictionary 25th Edition: Amazon.co.uk: Harry Newton: Books

This is the book I have used in the past. Pretty good book to have in your collection.

25th edition isnt available yet so go for 24th if you need right away.

Kaminsky

DPs are just distribution points where bulk phone lines come in to your site and terminate from the roadside cabinet into a Krone panel set on a large board or mounted in a cabinet. Each of these DPs come in strips of 10 pairs of punch slots and each strip has an upper and lower. Depending on the size of the core run to your building will relate to how many of these strips get installed into your DP. Each of these pairs will terminate into the upper on one of these pairs on your DP. When a new circuit is provisioned, they liven up a spare one of these pairs and you or the carrier engineer connects a pair of wires to the bottom of the pair by "punching it down" with a punch tool with the wires going no particular way round (but usually follow blue/bluewhite standard)and then run the usually 6 core cable (3 pairs) wherever you need it and then terminate that by "punching it down" in a little white box like you have in your home.

The bulk phone lines run back to a road side cabinet somewhere nearby where they connect to a bigger version of the same thing in the lower half of the cabinet on numbered pairs that the carrier knows, relate to your DP. This lower patch is called the D side. In the upper half of the road side cabinet are equivelent pairs that run back to the nearest exchange. Your carrier engineer patches the circuit from the relevent E side to the relevent D side in the roadside cabinet. In the exchange they patch it through to the relevent type of circuit the carrier will be providing. One continuous wire from exchange to device in your building. We've all seen inside these cabs when engineers are working on them by the roadside and they look like a nightmarish nest of wiring but they are very simple really. Upper E-Side "exchange" pair connects to the lower D-Side "customer" pair to bridge the circuit from exchange to inside customer premesis. Sometimes they get taken out by car crashes and have to be fully rebuilt and then repatched...

From your little white box, you can either have a standard analoge phone line or connect a micro filter into it and connect into a dsl box. If you have 64k, 128k or larger kilostream then that will connect to a kilostream NTU.

You can have other types where they put a large mux in from a single fiber, which is usually a 16x2mb port, 32mb chassis and whenever you want a 2mb pipe you either connect by D15 X.21 or rj45/bnc G703 connection. Run this straight into your router via the relevent interface WIC. This is usually where you see DB15 - db60/ss cables being used but they are also used with kilostream NTUs to connect to serial interfaces on the routers. You can also get smaller versions of these which are called ASDHs and are typically 4 port but work pretty much the same way from a comms guy point of view.

If you are going to have A LOT of private wires, it may be worth getting an exchange chassis fitted by the carrier (not cheap) and then you get each line presented on a line card instead of a stand alone NTU which can save you space and power.

Similar thing happens with fibre. Get fibre into the building, run one to your NTU and then they present from there usually on rj45 or fibre depending on the size and presentation you requested.

Of all the network disciplines, comms is the easiest. I say that as a data centre comms manager. You say how it comes in. You say where the box will go and then you work out the patching from that demarc to where you want it. When it comes to configuring the wan links then ccna or ccnp will show you how to get the best out of it. Apart from that, the carrier does all the hard work. You just have to pay through the nose for it.

If you study up on the complexities of comms protocols and equipement/interface types and try to talk to your carrier engineer about it you will get a completely blank look as the engineer on the ground typically doesn't know any of that stuff and will think you are just trying to be a smart a$$.

That's a brief overview taking BT as the example carrier. Hope that helps.

Pash

wireat- thanks for the book recommendation mate, really appreciated.

Kam- What can I say mate! Awesome explanation, many thanks for that.

One other thing I wanted to ask - as we are the private wire B end we don't actually host any equipment for these circuits (rather boring if you ask me!) - The BT dude in yesterday was telling me that fiber runs from the exchange directly to the fiber cabinets downstairs in the BT frame room and then from what I have been explained the fiber is then terminated to a wall frame where he punched in copper to the corresponding cables that go up to our customers floor where there is also a wall frame (our demarc point) and then we can punch in the circuit to the physical lines on our dealer phone system.

Are the splicers for the fiber connections hosted in the same roadside cabinets where the D to E side is for the copper lines (or is this all underground now) and how is the physical fiber changed to the copper used from the BT frame room downstairs to the 4th floor?

This stuff is mind boggling for me I guess, I just want to be able to draw a picture in my head about how the pysical layout is from exchange to site.

Thanks again.

laidbackfreak

Kam top explination there buddy

Pash fwiw I've got this in my collection :-
Telecom Basics 3rd Edition, Signal Processing, Signaling Control, and Call Processing: Amazon.co.uk: Lawrence J. Harte: Books

followed a recommendation from Telco guys on site here.

Pash

laidbackfreak wrote: »

Kam top explination there buddy

Pash fwiw I've got this in my collection :-
Telecom Basics 3rd Edition, Signal Processing, Signaling Control, and Call Processing: Amazon.co.uk: Lawrence J. Harte: Books

followed a recommendation from Telco guys on site here.

Cheers for the recommendation dude, how would you rate the book if you just needed to know the basics on telecom tech's?

laidbackfreak

Pash wrote: »

Cheers for the recommendation dude, how would you rate the book if you just needed to know the basics on telecom tech's?

I'd say it does the job lol I got it for exactly that reason.

It's an easy enough book to read and follow.

Kaminsky

Pash wrote: »

... as we are the private wire B end we don't actually host any equipment for these circuits (rather boring if you ask me!) -

The A and B end denote where the management of the link will be going... At the A end. This is typically a router or an extra management line card in the NTU and need an extra connection for them to manage the link at that end. The B end doesn't have this so you save on line capacity, extra power and U space. Even if you are the A end, you can't touch the router as it is in their side of the demarc and typically, even the on the ground engineers can't log into them either.

Pash wrote: »

The BT dude in yesterday was telling me that fiber runs from the exchange directly to the fiber cabinets downstairs in the BT frame room and then from what I have been explained the fiber is then terminated to a wall frame where he punched in copper to the corresponding cables that go up to our customers floor where there is also a wall frame (our demarc point) and then we can punch in the circuit to the physical lines on our dealer phone system.

Sounds like you already have exchange level equipment in your building. These will be runs of large bandwidth and are then partitioned off in much smaller chunks like a big mux. This will be exactly the same type of equipment you will find if you went and visited the local exchange. So, you have these big frames at either end of the link. The basic reasoning is that fibre can carry much larger bandwidths than analog copper and then they just stick in a box to split this off at the customer site.

Pash wrote: »

Are the splicers for the fiber connections hosted in the same roadside cabinets where the D to E side is for the copper lines (or is this all underground now) and how is the physical fiber changed to the copper used from the BT frame room downstairs to the 4th floor?

Typically yes but not necessarily and not in a mechanical way. Carriers will run large multi-core cables to specific geographic areas to feed prospective customers in that area and distance isn't really a problem with fibre. They do have limitations on the distance of multi-mode and single mode and the type of fibre but these are measured in kilometers.

Whereas copper will go to an E-Side, fibre needs to be spliced off from that exchange core to go to specific buildings in that local area. These smaller core of fibres are then typically presented into fibre trays as "Dark Fibre" (no light going through it yet) , which is just a pretentious way of saying "spares". If you know the conduit where this fibre comes into your building you can go look to see where the external core is spliced to the internal one - cream coloured to black core cable typically. Again, depending on how many spares are run to your building will dictate the thickness of the core.

This internal core is then run into a cabinet where the "spares" will live and each fibre from the core is then individually fed into special trays ready for future use. This initial installation can take days to put in. After that, when a new fibre circuit is provisioned, a fibre tailer will come in and take one of these spares and splice a fly-lead fiber from that tray to wherever you need that fibre to be run - ie where the NTU is going to go. This splicing can take an hour or so as it is very fiddly but a small box does the actual fusing of the two fibres and does a small x-ray of the cuts and the eventual fusing to show the quality. This is the same process as takes place at the roadside but takes days to tail all those core fibres - when you see a BT engineer sitting in a hole all day seemingly doing nothing, that's what they are doing typically. So, you get a solid piece of fibre all the way from the exchange, not necesarily the local exchange, to your on site NTU.

The splicing itself needs to fall within an upper and lower bandwidth. It must meet the minimum db but it cannot go over the maximum db or too much light will be hitting the fiber connections at the end of the fibre and, over time, they will develop a residue which will degrade the circuit and cause packet errors and impact the circuit's bandwidth. If the splice is too good, they will typically put a 2" long barrel attenuator on the end and run another short fibre to the device from the other side of this attenuator. You wouldn't have thought that light could be too good so they have to deliberately degrade it for longevity.

Due to Oftel breaking up BT into smaller companies (OpenReach, Global, etc) in the UK to stop a monopoly, another BT team will arrive several days later to fit the NTU and connect the fibre tail to it. If it is a single NTU les/wes/etherflow circuit it will have a card that fits in the right hand side of this device whether it is the A end or the B end. The fibre tail will connect into this device and on then present to the user on the same card with the desired "ready for use" presentation. These can be RJ-45 Ethernet (not RJ-45 G703) , SC/LC multimode/single mode. If this is the A end, there will be another card on the left of this NTU which is for the management connection of the link which will need another wan connection as well - typically PSTN.

You can also have these single NTUs in chassis form where the first line card just slots into the chassis and the management card in the chassis provides management for all the circuits in the device. However, this can be like puttin all your eggs in one basket and if you lose this device, you lose all circuits going through it.

However, this NTU could instead be various types of mux devices which seperate off that bandwidth provided by the fibre into smaller chunks of 2mb or higher which are then used to provide private wire circuits. This is becoming far more common and eventually will see the end of copper as everything becomes completely digital.

There is an exchange in Ealing, London that was having a building built nearby recently. Whether it was neglegence or the builders had the wrong underground utility maps I don't know but when using one of those big foundation pilon screw drills, they drilled straight through the centre of a huge fibre core going to the exchange, with thousands of live fibres running through it, and just mashed it to bits. Fibre tailers from all over the UK were drafted in 24/7 for weeks splicing that core back together.

Thats a rough explanation of how fibres work using BT again as a guide.

In the UK, BT will typically provide the last kilometer of infrastructure regardless of which company is actually providing your circuit. That other company leases the infrastructure from BT and then sell the circuit to you. This is the same the world over with their respective major carriers - BT, AT&T, Cable & Wireless, Verizon, KDDI in Japan, etc. Other companies specialise on inter-continental links which they then lease to these carriers.

Sorry for the long post.

Pash

What can I say, many thanks Kam. Ive gotta fill myself in with all the different types of connectors etc and get some good pictures in my head but that sure has helped me.

Ill be coming back to this thread many times no doubt!

Thanks again,

Pash

bellhead

Do a search on Bell Core training. Bell Core was AT&T's training unit and there is a manual out there for everything. You just have to find them but try Bell Core.

Pash

laidbackfreak wrote: »

I'd say it does the job lol I got it for exactly that reason.

It's an easy enough book to read and follow.

Dude I got that book from amazon and started reading it on the train already this morning. It's helping me already!

laidbackfreak

Pash wrote: »

Dude I got that book from amazon and started reading it on the train already this morning. It's helping me already!

nice one fella, glad its helping

JDMurray

The best site on the Web for Telco information is www.dslreports.com. I was jdmurray there long before I was jdmurray here.