Slow ADSL CQM

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 will make the line slow, but is not a fault

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.

Packet loss on the line

Packet loss is shown as dripping red from the top on the graph. Here are some examples:

Heavy packetloss. Packet loss on an idle line is always bad news...

...even if only 1% (one red dot at the top is 1%). An FTTC line with 1-3% loss

If you suspect you have packet loss, also see:

• Packet Loss - a page with more (slightly technical) details about packet loss
• CQM Page - Our general page about graphs with Packet Loss examples