Slow FTTP

Causes

There are a few things that could cause a FTTP circuit to be slower than expected.

1. A fault somewhere causing packetloss (this could be local to the customer's home network, or something further afield)
2. Some miss-configuration or fault in the fibre provider's network (eg broken links causing congestion)
3. Congestion somewhere between the premises and the internet causing slow-downs
4. Something else

Things to be aware of

FTTP from providers like BT or CityFibre use GPON or XGS-PON technology to run fibre from their core network to your premises. This is a shared service, which means you do not have guaranteed sole use of the bandwidth that your physical connection is provided at. eg, a 1Gb/s connection does not mean that BT or CityFibre guarantee that you will have 1Gb/s throughput. Both BT and CityFibre have figures for the guaranteed speed which will me much lower than the connection speed.

eg, with CityFibre, their 1Gb/s service has a download "Committed" rate of 70Mb/s and BT's 1Gb/s service has a minimum speed of 195Mb/s. More info of the rates on: https://www.aa.net.uk/broadband/fttp-speeds/

Finding the cause of slowness

When faced with a slow service, the challenge is to find the cause. If a cause can be found then a solution can be found, or at least, explained.

Things to test and try

Here is some steps to take if you have problems with your FTTP service.

If your FTTP service is slow, eg a speed test is not reporting expected speeds, then try these:

Checking the hardware and connections

1. Try a wired connection from your computer instead of WiFi to rule out any WiFi problems.
2. Try a power cycle of the Openreach/CityFibre ONT - always worth a try!
3. Connect your computer directly in to the router - so as to bypass any other switches you have - this will help eliminate other equipment in the path to your router
4. Ensure the router is capable of the speed of the circuit - eg, maybe you have a 1G service but an older router? - let us know the model you are using
5. Try a laptop/PC plugged directly in to the ONT instead of using your router - set up a new network connection of type PPPoE and use your xxx@a login and password to connect, and run a speed test. see: PPPoE_on_a_Computer for more help on this.
6. Try a different computer/device
7. Check/swap the cable between the ONT (The Openreach/CityFibre unit that the fibre connects to) and your router - ensure it's a 8-wire CAT5 or CAT6 cable - not one with 4 wires as these will run at 100M and not 1G.

Actual tests to run:

1. ping tests:
   running ping tests from the 'command line' can help see if there is any strange loss or latency.
   1. ping your router:
      This will test your local connection. eg, if your router (gateway) is 192.168.0.1 then run:

      ping -c 100 192.168.0.1

      and let us know the last few lines containing the results, which show any loss, the latency and jitter, eg:

      --- 192.168.0.1 ping statistics ---
      100 packets transmitted, 100 received, 0% packet loss, time 100970ms
      rtt min/avg/max/mdev = 0.137/0.172/0.736/0.068 ms

   2. Ping our network:
      This will ping through your router to us, and therefore tests your connection to our network

      ping -c 100 81.18781.187

2. Speed test web sites:
   Use ours and some other 3rd party ones to check up and download speeds run these at different times of day as this can help track 'peak time congestion'. note - many http speed testers are not very good for testing 1G connections - always take results with a pinch of salt
   1. https://speedtest.aa.net.uk
   2. https://www.fast.com
3. Check the CQM Graphs, via the Control Pages, to see if it is slow due to lots of traffic.
4. Ask us about testing with 'iperf' - as this is generally better than http speed test websites. See: https://support.aa.net.uk/Windows_iperf3
5. Check for packet loss - see below.
6. ...get in touch.

Always worth running a test, even if LOS light is off - there could be a problem further upstream and Openreach may already be aware or we'll need to report a fault:

• Run a test:-
  1. Our Control Page will allow you to run an 'End to End' test, this may if Openreach's systems detect a fault, in which case, do get in touch. eg: GTC_FTTP_SERVICE_1005 Possible fault in the Openreach network.

Single thread Vs multi thread performance problems

Sometimes a speed problem occurs for single-thread transfers, whist multi-thread transfers are OK. Broadly speaking, single thread Vs multi-thread speeds should be very similar, and near the top end of the speed of your circuit.

These can be tricky to diagnose and fix, as sometimes the problem is down to congestion in the back-haul network.

As well as testing the usual things (Different computer/router/directly-wired etc) to help diagnose, we suggest using iperf3 rather than http based speed tests as iperf3 is usually more reliable.

Support staff can give access to our own iperf server, and then you can run tests such as:

Single thread transfer from us to you (testing your download)

iperf3 -R -c <speedtest server>

10-thread transfer from us to you (testing your download)

iperf3 -R -P 10 -c <speedtest server>

Single thread transfer from you to us (testing your upload)

iperf3 -c <speedtest server>

10-thread transfer from you to us (testing your upload)

iperf3 -P 10 -c <speedtest server>

Running these at different times of day will give a picture as to whether single-thread is a problem, and if it's a problem due to the time of the day.

example

Here is an example where we are running a single thread iperf3 test for 10 minutes, and then a 10-thread test for 10 minutes - the difference is shown clearly in our CQM graphs:

Alternating between single and multi-thread iperf download tests

The graph should look like this, with equal and full speed for both single and multi thread tests:

Good speeds

I may have packet loss

Packetloss can be seen in a number of ways, check the following to see if the location can be narrowed down to something specific:

1. Ping your router's LAN IP - this will be the 'default gateway' your computers use - eg, could be something like 192.168.1.1 - if you have loss pinging your local router, check with a wired connection direct in to the router...
2. Check the CQM Graphs on the A&A Control pages
3. Ping the A&A endpoint IP: ping 81.187.81.187
4. ping somewhere on the internet, eg ping 8.8.8.8 and ping bbc.co.uk

Get in touch with us about what you find.

Intermittent low levels of packet loss

Wrongly configured OLT

Packet loss with an odd pattern like this was seen after a CityFibre OLT was upgraded in March 2023 and apparently have some wrong configuration and caused around 5% loss:

Loss caused by a missconfigured CityFibre OLT after being having a firmware upgrade

Slow CityFibre since migrating

We have seen CityFibre connections limited to say 500M when they have been migrated over to us. This could be due to the previous service being a 500M service and CityFibre's systems not updating the profile/bandwidth for the circuit. This can be tested with connecting a PC to the ONT and setting PPPoE_on_a_Computer - if around 500M is the maximum then let us know. The fix is for CityFibre to re-provision the ONT, which we can request.