Random Reviews

I wanted to write this article for a long while because I knew that networking is such a new technology, it seems at times that no one seems to know how it works. The situation is really quite bad, even among people who work in the field believe it or not. But having done technical support for companies providing both LLU and non-LLU internet (I’ll explain later) I know that customers have fast less clue about what’s going on than anyone. Now, this is not going to be an in-depth technical discussion, but I am going to keep this as more of a practical guide to help the customer get a better picture of what’s going on under hood. Just enough so that he/she can know that if they can’t print their emails, it’s not an Internet problem, and yes I have had calls complaining that the Internet is broken because they can’t print their emails. So, let’s get on with it.

Layout

The first thing that we might as well start with is what is plugged into what. Now not every setup is exactly the same, however there will more often than not be similarities.

1. First have your computer which is going to be plugged into your router (could be modem, but we use routers when we want to be able to plug more than one computer into an Internet connection at once).
2. Your router may have a built in modem or it can connect to one, most modern home setups for ADLS have a router with a modem built in. The cable that your computer uses to connect to the router/modem is called a cat 5 cable or Ethernet cable, but many times you will also just here it called a network cable. It uses the electronic protocol (language) called Ethernet and the electronic protocol acts as a carrier for other protocols. We call this encapsulation (important term, getting this one well understood here will save so much time and confusion). Encapsulation is like the way that air carries sound and sound carries words and words carry sentences and sentences carry meaning. Just like a Russian doll, one thing is hidden inside the other. Well, the computer connects to the World using Ethernet. The router connect to the modem using Ethernet, then it all changes.
3. The modem dispenses with the Ethernet coming from your computer and speaks ADSL language from your telephone point to the exchange (also known as your synch rate). Your normal voice calls don’t use most of the bandwidth so ADSL can send these signals and take up the rest of the available bandwidth after going through the splitter, if the splitter is damage strange things can happen, funny noises on the phone, no broadband. Broadband only when someone is on the phone. There should be no telephone extension between the modem and the master phone socket, this is the cause of endless troubles! ADSL uses something called Quadrature frequency/Phase Modulation. Won’t go into that lets just say, for those really interested its like FM with an AM twist down your phone line, won’t explain that because knowing that won’t help get you connected.
4. Signal then goes down your phone line to the exchange where (I’m going to describe how its done in the UK, can’t imagine its too different if all where you live) its picked up by a part of the exchange called the Bar Pair, it then goes from the Bar Pair to the MDF – Main Distribution Frame. These places are just points involved in the organisation of the exchange, the signal isn’t changed. It then goes from the MDF to the British Telecom (The UKs incumbent telecommunications company) TAM – Test Access Matrix. Long name, but all it is, is a line testing device. The signal exits the TAM then goes on to the DSLAM/MSAN DSL Access Matrix / Multi Service Access Node (They love their long names don’t they?) Simple really, DSLAM takes the broadband – MSAN takes the voice. If you have broadband with a very high speed internet provider (not BT) then it is more likely that it is with an LLU company – Local Loop Unbundled. In this case, the signal goes from the BT TAM to the HDF – Hand Over Distribution Frame, then it hits the DSLAM before being passed back into the ISP’s network. Got that?
5. It then goes from there to something called a BRAS Broadband Remote Access Server. This handles the username/password and speed that you have on your modem/router.
6. From there through a bunch of switches and routers at your ISP to the Internet.

The Connection

So that’s probably the most complicated part of this article in the layout. Now we need to explain the virtual path and just why knowing these things can really help save your time when trying to troubleshoot your connection.
So, just how fast is your connection? Well, the connection from your PC to your router is usually going to be about 10mb or 100mb – OK this is WAY faster than your Internet connection will be, so when you see that little icon in the bottom right hand corner of your screen saying that your are connected at these speeds, know that it is just talking about your connection to your router, not to the Internet. To test a connection to the Internet, you need to type speed test into a search engine and take it from there. The speed from your modem to the DSLAM is the million dollar question. This is determined by the quality of the cabling in your house (cannot be understated!) and the quality of the cabling to the DSLAM along what’s termed the MPF – Metallic Path Facility. This is the cable and connections going from your home to the exchange, but you need to know that this is handled in the UK by British Telecom and if there is a problem with it in terms of poor broadband – or you would just like it better. Nothing can really be done about it. BT will just tell your ISP to go jump, it costs a lot of money for BT to send out an engineer and improve it beyond voice capacities (if at all possible), so BT are not interested.
The sync rate is determined by the quality and length of the conductor used in the MPF. The longer, the slower the ADSL speed that you can have from home. Now it is important to know this, and very often you can find the current sync rate from your router by going into it (check the manual for details). It can happen that the sync rate is a lot higher than the actual speed of your Internet. This can happen for a number of reasons. By far the most common is spyware. Just go into start -> run ->cmd -> in the black window that appears type netstat then count number of lines that you see. If it is more than 10, (each one represents a connection to the Internet) and you don’t have bittorent of something like that running your computer is probably infected. After that another problem that it could be is that your profile on the BRAS is wrong. If that is the case, then it should be easy for the ISP to fix. They just need to update your profile, you switch off your modem, then switch it one again, then your away. But another reason for slow connection is called – ready for it, another long sentence with an easy explanation. Over utilisation of the VP, VP = Virtual Path. Essentially what this means is that the ISP has bundled your Internet connection with other peoples and when they start doing some heavy downloading, your internet connection has to slow down. This is again something that the ISP can fix, if your problem is really quite acute. You can often recognise this if your Internet connection gets bad at evenings etc.

The Service

The last thing that it is really important for people to know is what service you actually purchase from your ISP. In most cases it’s called a wires only service. This means that they provide the utility of an ADSL signal down your telephone wire and its stops at your BT master box. Specifically behind the face plate – I kid you not! The BT face plate is removable and behind it your will see a test socket. This is where the support from the ISP runs out with wires only services. So as long as they know that the ADSL signal is reaching that point, then they may well say, that their job is done. Just like your electricity or gas company. Anything after the tap/socket/plug is your business. So that’s kind of why I wrote this guide, to help give people a little knowledge and to know where to start. This is by no means the end of everything there is to know, but it will get you started.
Thanks for reading!