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CQM Graphs: Difference between revisions
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→Examples of things that are not a fault
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If a line is dropping during the day, and maybe just Monday to Friday, then it's probably not going to be an upstream problem. This could be caused by interference of bad wing on site. Check things like the phone line and extensions. Put the router in master socket and to unplug all other phones. Maybe change filter.
==Other Examples of things that are a fault==
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|[[File:Cqm-loss.png]]
|'''Dripping Blood'''
Packet loss on an idle line is always bad news, even if only 1% (one red dot at the top is 1%). If this happens on several lines at the same times of day this usually means congestion on the back-haul to the exchange or elsewhere in the network. If it is steady loss all day it can mean a fault on a line card or interference on the line.
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|[[File:Cqm-long-grass.png]]
|'''Long grass'''
Some issues can be subtle, affecting latency on idle lines like this with occasional peaks. Even low levels of jitter like this can disrupt VoIP and can indicate a wide problem such vendor equipment bugs or the start of back-haul congestion.
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|[[File:Cqm-latency.png]]
|'''Speed bumps'''
Latency humps like this are normally a sign of back-haul congestion. They normally show on all lines on an exchange or BRAS at once at the same time of day, and only show at certain (busy) times. The clue here is the consistently high latency even when little or no traffic flowing.
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|[[File:Cqm-dropping.png]]
|Going off line is shown in purple, and this is often associated with packet loss (red). Where a line has occasional drops they are shown as purple lines. However in some case a line can deteriorate over a period of time, staying on line less and less until solid purple (off line). On the live graphs a line that is currently off line has a red square in the bottom right corner where as a line that is on-line has a green square.
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|[[File:Cqm-congestion.png]]
|A congested link in the back-haul can show as loss or latency humps on an idle line, but in some cases, like this, it can show only where there is traffic on the line. The symptoms are latency spikes like this (green spikes) even when there is very low usage. Compare to normal graph below.
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==Examples of things that are not a fault==
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|[[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.
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|[[File:Cqm-sawtooth.png]]
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