CQM Graphs: Difference between revisions

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

|'''A normal graph shows''' no packet loss (no red at the top) and little of no change in latency when downloading or uploading at low rates. Compare to congestion graph above.

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

|This graph has a saw tooth latency pattern. This can sometimes be just in green (peak) latency or in blue (minimum) latency or some combination of the two. It can be regular like this or change frequency. This is just the way this specific make of router responds to LCP echos and is not actually affecting traffic.

|[[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.

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