VDSL Output Information

Current Throughput:
Your current receive and send sync speeds

The latency between your router and the cabinet (Note these figures can vary by 1-2ms at times, but will be on or around 1, 8 or 16 depending on which DLM profile you are on – see further down). 

Shows whether bitswap is active or not.  Bitswap is a method by which frequencies which have excessive noise are swapped out with other frequencies with less interference.

Impulse Noise Protection (INP):
INP attempts to compensate for noise on your line by using a 4 different profiles.  This is determined automatically by DLM.

Signal-to-Noise Ratio Margin (SNRM):
This is the SNR margin which is the amount of SNR reserved as a ‘buffer’ to allow for unexpected noise.  It is the the difference between your current SNR and the SNR required to maintain a stable connection at your current connect speed.  The lower the SNR margin is, the more SNR can be allocated to data transmission and therefore the higher your sync, and subsequently your throughput, will be.  Of course, a lower SNR margin leaves less reserve for errors, so there is a tradeoff.  If your SNR margin drops from say 12 to 11db, then you are one db closer to hitting the lowest acceptable SNR figure. *3 *8

Line Attenuation:
This is the amount of signal lost between the cabinet and your router.  As detailed below, you can also calculate a rough estimate of your line length using this figure.

Carrier Record:
I am unsure what this is, but it seems to be the same (A43) for all snap users at least.

This is the Bandplan profile that your connection is currently using.  This will be either 8b (50mbit max) or 17a (70mbit max).  At this point it appears that Chorus will not manually change your Bandplan profile and the only way to get to a 17a profile is if DLM determines that it is appropriate to do so.  According to information from Chorus, line length must be less than 350m for 17a to be activated.  While this doesn’t necessarily correspond with a particular attenuation figure, values as high as 7dB have been observed prior to some lines being swapped to 17a.  If your line meets the length requirements, a swap to 17a is attempted if the last Bandplan switch was more than 90 days ago.  Note that this is different to your DLM Profile (see below).

Errors (ES):
ES means ‘Errored Seconds’ and is the number of seconds during the current sync session where one or more CRC errors have occurred.

Many Errors (SES)
SES means ‘Severely Errored Seconds’ and is the number of times where there has been 10 consecutive Errored Seconds.

Remedial Errors (FEC):
FEC stands for ‘Forward Error Correction’ which is a method of correcting errors introduced during data transmission without having to re-send any data.  These errors have frequently been observed from as low as 30 to as high as 2000 per minute but do not indicate any issues to be concerned about. *6

Non-Remedial Errors (CRC):
CRC errors occur when FEC is not able to repair corruption in the data transmission.  These are the errors that you need to be concerned about.  The closer this figure is to 0 the better, but from our testing it appears that it is possible to have a ‘CRC Per Minute’ (CRCPM) rate of up to 10 and still maintain a stable line on the DLM-1 profile (see the ‘Dynamic Line Management’ section below).

The ‘Per Minute’ figure in this section can be used to calculate the Mean Time Between Errors (MTBE) which is used by DLM as one of the measures of line stability.  In order to get the MTBE, divide 1 by the CRCPM figure and you will get the number of minutes between errors.  Eg; if your CRCPM is 0.1; 1 / 0.1 = 10 minutes between errors.

Source: https://www.geekzone.co.nz/forums.asp?forumid=90&topicid=105744

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