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Slow FTTP: Difference between revisions
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[[Category:FTTP Faults]]
==
This page has lots of information and guidance on dealing with a slow FTTP connection. We suggest it's read by customers and that we then work with you. The page covers slow FTTP with BT Openreach and CityFibre connections.
The information here has a number of objectives:
*Explain what could cause slow speeds
*Explain the problems with dealing with slow speeds
*Try to manage expectations about timescales and what to expect from a 1Gb/s connection
*Provide various tests the customer can perform and send the results in to our support team
*Provide questions that will help A&A support staff further investigate
=Background information=
==Causes of slow speeds==
There are a few things that could cause a FTTP circuit to be slower than expected.
#A fault somewhere causing packetloss (this could be local to the customer's home network, or something further afield)
#Some
#Congestion somewhere between the premises and the internet causing slow-downs
#Something else
==Useful things to let us know==
When reporting a slow connection fault to us it is always useful to have some background information. Answering these questions will help us get a better understanding of the story:
# Describe what is slow. (eg a game, streaming, video calls, downloads, etc)
# When did the connection become slow (the date)?
# Can you think of any change that happened at the time the connection started to be slow?
# Was the connection slow with a previous ISP? If so, what was the story there?
# Have you already had engineers out to investigate? If so, what did they say?
# Is it slow at particular times of day?
# Do you know if your neighbours also have slow connections?
==Things to be aware of==
===Committed rates===
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:
*CityFibre 1Gb/s = '''70Mb/s'''
*BT 1Gb/s ='''195Mb/s'''
Whilst we would expect to see our customers get near the full line rate, this is not guaranteed, and can be complex and long-winded to resolve if the cause of the low speed is due to the back-haul network and the speeds observed are within specification.
In short, we, and our suppliers are within their right to say a 1Gb/s service is working to acceptable standards if the observed throughput is above the figures above. The service is working within the acceptable range. so, contractually, a 1Gb/s service running at 200Mb/s is not a fault. More info about these rates on: https://www.aa.net.uk/broadband/fttp-speeds/
That said, in practice, we would expect to see our customers get the near full line rate. Just bear in mind the service being purchased does have levels of acceptable speeds.
===SLA===
Whilst BT and CityFibre will have SLA (Service Level Agreements), these usually cover where there is a physical fibre fault and that the times they state would be the anticipated time it would take to fix. Faults can take longer than the SLA to fix.
The SLA would also not be relevant where a speeds are above the 'committed' rate, as according to BT/CityFibre, the service would be working within the specified terms.
===Long standing problems===
We do get customers moving from a previous ISP to us having had a slow speed problem with the previous ISP.
In these cases, sometimes the slow speed problem disappears the day the service is migrated to us. However, sometimes the slow speed continues. In these cases moving ISPs has helped to narrow down the cause of the problem as a large part of the connection (ie the ISP) has changed. However, the back-haul connection, from your premises to the ISP may not have changed and could be the cause of the fault.
We will try our best but faults where a customer has had previous problems with an ISP, or ISPs, and has moved to us and still has the same problem can take a much longer time to fix, and in some cases it may not be possible - especially if the speed is above the committed rate and all avenues of investigation have been exhausted.
==Working with us, not against us==
At A&A we do work hard on diagnosing and fixing faults for and with our customers. A slow fibre fault is not always easy to fix - there are many places that could cause slow downs and a fault is not always clear.
We do need cooperation from our customers in running tests, swapping things around and so on. These tests may need to be repeated at different times of day and after a change has been made. This can seem like a waste of time, but this testing and cooperation is needed and is appreciated.
On the other hand, we will work with our suppliers - BT/CityFibre etc, and we do and will escalate and chase for updates. We will also push back if they ask us to do things that are clearly not going to help.
=Investigating the cause of slow FTTP (getting practical)=
==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.
If the problem is easily visible - eg constant packet loss, dropping PPP, high latency then these sort of faults are far easier to resolve than a line that looks perfect in terms of loss/latency but suffers with lower throughput than anticipated.
== Things to test and try ==
===Checking the hardware and connections===
#
#
# '''Ensure the router is capable of the speed'''
# '''Different computer/devices''' <br> Always worth trying different computers just in case one has a problem.
▲# '''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
# '''Check/swap the cable''' <br> 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.▼
# 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.▼
# '''Different router''' <br> If possible, try a different router. If not possible, connect PC directly to the ONT as below.
▲#
# Check the '''CQM Graphs''', via the Control Pages, to see if it is slow due to lots of traffic. - staff can help explain the graphs and check them over.▼
===
These are tests you can from your computer, some of them (eg the ping) will need you to use a command prompt or terminal to enter the commands. Do get in touch if you need help with how to do that.
#'''ping tests:''' <br> running ping tests from the 'command line' can help see if there is any strange loss or latency.▼
# '''View the CQM graph'''
## '''ping your router:''' <br> This will test your local connection. eg, if your router (gateway) is 192.168.0.1 then run: <syntaxhighlight>ping -c 100 192.168.0.1</syntaxhighlight> and let us know the last few lines containing the results, which show any loss, the latency and jitter, eg:<syntaxhighlight>▼
#* We plot loss/latency/traffic graphs and these can be seen on our Control Pages - viewing those is the first port of call, as loss and latency are easily spotted. Feel free to ask our support team to help explain them.
#* There are some example CQM graphs at the end of this page
#* 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:▼
▲#'''
▲## '''ping your router:''' <br> This will test your local connection. eg, if your router (gateway) is 192.168.0.1 then run this to send 100 pings: <syntaxhighlight>(on windows) ping -n 100 192.168.0.1</syntaxhighlight> <syntaxhighlight>(on Mac) ping -c 100 192.168.0.1</syntaxhighlight> and let us know the last few lines containing the results, which show any loss, the latency and jitter, eg:<syntaxhighlight>
--- 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</syntaxhighlight>
## '''Ping our network:''' <br>This will ping 100 times through your router to us, and therefore tests your connection to our network <syntaxhighlight>(on windows) ping -n 100 81.18781.187</syntaxhighlight> <syntaxhighlight>(on Mac) ping -c 100 81.18781.187</syntaxhighlight>
##'''Ping with larger packet sizes''' <br> normal pings send small packets, sometimes a problem can affect large packets, so try these two pings, and send in the results: <syntaxhighlight>(on windows) ping -n 100 -f -l 1400 81.18781.187</syntaxhighlight> <syntaxhighlight>(on windows) ping -n 100 -f -l 1472 81.18781.187</syntaxhighlight> <syntaxhighlight>(on Mac) ping -c 100 -D -s 1400 81.18781.187</syntaxhighlight> <syntaxhighlight>(on Mac) ping -c 100 -D -s 1472 81.18781.187</syntaxhighlight>
#'''Speed test web sites:''' <br>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. That said, ''Expected results:'' The speeds tests should show around 900Mb/s download speed
## https://speedtest.aa.net.uk
## https://www.fast.com
# '''iperf''' <br> Ask us about testing with ''''iperf'''' - as this is generally better than http speed test websites. This can test single and multi-thread, upload and download. See: https://support.aa.net.uk/Windows_iperf3 Running an iperf for 10 or 20 minutes is a good idea, as this will then be seen on our CQM graphs, and that may show loss/latency etc, and also run upload and download tests along with single and multiple threads.
▲# '''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.
## <syntaxhighlight>iperf3 -R -P1 -t 600 -c speedtest.aa.net.uk # Download, singlethread, for 10 minutes</syntaxhighlight>
▲# Check the '''CQM Graphs''', via the Control Pages, to see if it is slow due to lots of traffic.
## <syntaxhighlight>iperf3 -P1 -t 600 -c speedtest.aa.net.uk # Upload, single-thread, for 10 minutes</syntaxhighlight>
## <syntaxhighlight>iperf3 -R -P10 -t 600 -c speedtest.aa.net.uk # Download, 10- thread, for 10 minutes</syntaxhighlight>
## <syntaxhighlight>iperf3 -P10 -t 600 -c speedtest.aa.net.uk # Upload, 10-thread, for 10 minutes</syntaxhighlight>
#'''Other tests'''
## Search Youtube for a '4k test' video, and see if that streams smoothly - there are various nature/landscape videos that are high quality and should stream nicely
# ...'''get in touch'''.
=More advanced topics and areas of investigation=
▲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:-'''
Below are some more specific areas of investigation and examples of our own CQM monitoring graphs.
▲*# 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: <tt>GTC_FTTP_SERVICE_1005 Possible fault in the Openreach network.</tt>
== Single thread Vs multi thread performance problems ==
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:
[[File:FTTP-misconfig-olt.png|frame|none|Loss caused by a
==Slow CityFibre since migrating==
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