Slow ADSL CQM: Difference between revisions

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Here is an example of a CQM Graph with lots of upload traffic,
Here is an example of a CQM Graph with lots of upload traffic,


[[File:CQM1.png|none|frame|Lots of upload at the end of the day]]
[[File:CQM-FTTC-upload.png|none|frame|Lots of upload in the morning - a backup without any traffic shaping on the client end]]

The example above show a line with occasional short uploads causing spikes in peak latency, and then a sustained upload starting at around 6pm and causing high latency (queue in the router). At 8pm there was more upload filling the link causing higher latency still and some loss (normal when the link is full). This is normal.It may cause the line to be slow. If you don't know what the traffic is, then you can do a [[Traffic Capture]] or ask Support to Help.


This line is doing a large backup from just before 6am. The dark red horizontal line shows the traffic, during this time there is lots of packet loss (red) and the light blue at the bottom is showing high latency. So, whilst the backup is happening the line has about 50% packet loss and around 300ms of latency. Using the line for things like web browsing at this time will be slow and sluggish. However, this is not a fault per-se. It is normal for a line to appear slow when it's being filled with traffic. However, this traffic may be unknown, it may not be a backup, but could be a virus or peer-to-peer traffic. You can do a [[Traffic Capture]] to see what the traffic is, or ask Support to Help.


==Sync rate has been capped or lowered==
==Sync rate has been capped or lowered==

Revision as of 10:45, 10 March 2015

Using our CQM graphs can give you a good idea as to what could be causing a line to be slow.

You can take a look at your graph and compare it to the examples below to see if there is a match.

Lots of traffic on the line

Here is an example of a CQM Graph with lots of upload traffic,

Lots of upload in the morning - a backup without any traffic shaping on the client end

This line is doing a large backup from just before 6am. The dark red horizontal line shows the traffic, during this time there is lots of packet loss (red) and the light blue at the bottom is showing high latency. So, whilst the backup is happening the line has about 50% packet loss and around 300ms of latency. Using the line for things like web browsing at this time will be slow and sluggish. However, this is not a fault per-se. It is normal for a line to appear slow when it's being filled with traffic. However, this traffic may be unknown, it may not be a backup, but could be a virus or peer-to-peer traffic. You can do a Traffic Capture to see what the traffic is, or ask Support to Help.

Sync rate has been capped or lowered

You can check the linerate of your line - this is the speed of the line as reported to us by the back-haul provider.

Examples:

Line rate as shown on the control pages, ie 39.8M - Good!
This one has a rate of 338k - something is wrong!


  1. Log in to the Control Pages
  2. The line rate is usually shown on the front page, as per the image above

Packet loss on the line