Basic EFM Troubleshooting Guide

This is a basic EFM troubleshooting guide. Before proceeding, you should try to eliminate any potential problems with your own network. Please see our Basic Connectivity Troubleshooting Guide for more information on this.

What is EFM?

EFM stands for Ethernet First Mile. It utilises some elements of ADSL technology combined with elements of fibre and leased line technology to provide a low cost alternative to traditional fibre leased lines. Typically the speeds achieved on EFM lines is between 10 and 15Mb, although depending on location and distance from the exchange, you may achieve speeds lower and higher than this, sinking as low as 5Mb or going as high as in excess of 20Mb. The speeds on an EFM should always be symmetrical, achieving more less the same upload as download speed. The circuits also usually come with a much more enhanced SLA than that of ADSL, so if your circuit does go wrong they generally get fixed a lot quicker.

The “first mile” part of the name refers to the portion of connection between your premises and the provider’s exchange. Using a demarcation box that sits between your router and the wall socket, the technology is able to synchronise and bond several copper wires (typically referred to as “pairs”) together, providing higher resilience and better speeds. Most providers offer a two pair or four pair product, but we are seeing larger lines now with some offering six or eight pair connections.

It is important to remember that although an EFM connection is a form of fibre leased line, it used the same infrastructure and technology as ADSL. This can be very useful when learning how to troubleshoot and diagnose problems with ADSL.

My EFM connection is down

When your EFM connection is hard down, it is treated much the same as an ADSL connection. As previously explained, the technology involved in with an EFM circuit is very similar to ADSL, and understanding it can help you troubleshoot it more effectively.

Always try rebooting the kit first. This includes the router and the demarcation device that sits between the router and the wall socket. With EFM there are far more wires involved, hence there are more points in which a break can happen, so check all connections are seated and connected properly – the paired wires from the wall into the demarcation device (typically referred to as “Y Cables”), and the wire that connects this device to your router.

If you have rebooted all of the kit, made sure that everything is connected as it should be and eliminated it being a problem with your own network (please see our Basic Connectivity Troubleshooting guide), then you have little choice but to speak to your EFM provider and log a fault with their support desk. Going to them with as much information as possible is always handy, so make sure you tell them that you have checked all of the connections and rebooted / reseated everything where applicable. When your EFM is first installed, it is always a good idea to familiarise yourself with the technology and boxes when they are in a happy, working state. Make sure you know what the lights on the demarcation box should show when working, and also those on your router. You can identify the status of the connection from the demarcation box to the exchange, from the demarcation box to the router, and the status of the individual pairs, all by keeping track of the lights on the front and back of your bits of kits. This means that in the event of something going wrong, you will be able to tell if something is amiss and convey this information to the support desk. These lights may seem insignificant when everything is working, but knowing what is different when something goes wrong can speed up the process dramatically, especially those on the demarcation box.

My EFM connection is running slowly or intermittently

Much like the ADSL technology that EFM circuits are based on, EFM circuits can be prone to intermittency or slow speed issues, but these problems are definitely a lot less common with EFM, so if you find that these problems keep occurring on a regular basis, definitely raise this with your provider’s service department.

EFM is based on a number of individual copper lines bonded and synced together, so if you are experiencing a slow or dropping connection, it is very likely that this is being caused by one of these individuals pairs having a problem. EFM behaviour can be difficult to predict, but it is common for problems with the first pair (or Pair 1) to affect the entire connection as a whole, where as problems with the other pairs tend to not be as noticeable and can go undetected for a period of time. However this is not a solid rule and the opposite can occasionally also be true.

If you find that the connection is running slightly slower than it does normally, it could be that just one of the pairs has failed but the rest of the connection is working fine. Speaking to your provider support desk should be able to identify problems such as this. Just as an ADSL line has profiling and configuration information set up on it at the exchange and with your ISP, the individual EFM pairs all have similar data in place also. Getting to know your EFM line and having regular conversations with your support desk when it is first installed can help “tweak” all of this data to get the optimum performance possible out of your circuit. Imagine maintaining 4 different ADSL connections all at once, trying to get them to work in harmony with each other to extract the best performance possible. Again, familiarising yourself with all of this information on installation and while the circuit is working happily can help you and your support desk identify where something is going wrong when there is a problem.

EFM connections tend to be more resilient to radio or electrical interference than ADSL, but it is still a good idea to make sure there is nothing massively obvious that could be causing these problems. Please refer to our other guides on Basic Router Troubleshooting and Basic Connectivity Troubleshooting for more information on this.