CQM Graphs: Difference between revisions

 

 

!colspan="4"|Examples of things that are not a fault

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|[[File:Cqm-green-spikes.png]]

|Some makes of router can also cause the occasional LCP echo not to be answered until the next one, causing 1 second latency spikes to appear making green lines like this. This is just the way the router handles LCP echos and is not a problem as such.

|[[File:Cqm-full-uplink.png]]

|This graph shows very high latency initially, with blue filling the graph (500ms) much of the time and green the rest of the time. However the red line at the same time shows the uplink is being run at full capacity so the latency is just down to the queue in the router. Later the uplink rate is reduced and the latency drops away to a low level with some small peaks. During the high upload you will also notes a few red dots at the top (packet loss) also caused by the upload.

|[[File:Cqm-notes.png]]

|Purple on the graph is off line, and this can be short blips if a line loses sync or longer. Notes (pins) are often added to graphs to explain why a line is off line if we know, especially when we are investigating a fault. The notes on this graph told when the BT engineer arrived and left.