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CQM Graphs: Difference between revisions
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=Other Information=
===Rate limit line - red dot at bottom of graph===
BT run a rate limiter for your line at the BRAS. It limits traffic to a set level (typically whole Mb/s) that is below your line sync speed and can change over time depending on your line. We track this BRAS rate and set the CQM system to show this on the graph. It can only gets recorded per hour so shows the highest it was - with a dotted line for the lowest in the hour. You can ask us to limit your line below the BRAS rate - what is shown is the rate we have on the line for you service..
Tracking the BRAS rate is also important for load balancing multiple lines and attack detection.
===Why only 24 hours of history?===
Actually, each day, we archive the previous days graphs. This allows us to see a history of a line which is invaluable for intermittent faults or repeat faults.
===Why all lines, not just those with faults?===
We have to send LCP echos anyway to tell if a line goes off, so we may as well record the data. Sending one every second means we have very detailed information. When a fault does happen we have a full history already available, and this greatly speeds up the process of getting faults fixed. Another important point is that we can immediately see when a fault affects multiple lines as we are monitoring them already. We can even spot faults that our customers have not noticed yet.
Monitoring all lines also allows us to identify core network issues in carriers like BT and get them fixed.
===How is this information used?===
We make the information available to customers to see their own lines, and dealers (e.g. IT consultants) to help their own clients. We also make the information available to BT in the event of a fault on a line to help them understand the nature of the fault. The graphs allow us to identify many types of faults immediately and so ensure they are fixed more quickly.
===I see grey bands on my graphs===
In addition to the graphs from the FireBrick we add some extra information. This includes pins on the graph we can add to lines or groups lines to show know issues or events. We also add grey bands to mainland UK graphs which show night and twilight based on your postcode. This allows us to see any light related issues, such as automated security lights with a fault that affects the broadband. It also looks cool.
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