Is this DLM in action?

My upstream speed with BT seems to be moving around a lot. The IP stays the same but my Billion 8800NL R2 says the link connection has been reset. I've not got the complete log for the last rest 3 days ago. Here are some stats from TB speedtest.

Date Down HTTPx6 Down HTTPx1 Upstream IP Address ISP
Thu 09/09/2021 17:15 47.67 Mbps 46.96 Mbps 7.41 Mbps 86.139.252.XXX BT
Fri 03/09/2021 16:05 46.20 Mbps 45.44 Mbps 3.80 Mbps 86.139.252.XXX BT
Tue 24/08/2021 07:31 45.30 Mbps 44.85 Mbps 7.11 Mbps 86.139.252.XXX BT
Mon 23/08/2021 07:56 45.41 Mbps 44.26 Mbps 7.35 Mbps 86.190.195.YYY BT
Sun 22/08/2021 13:17 47.36 Mbps 48.35 Mbps 8.26 Mbps 86.139.254.ZZ BT

Thanks

Paul

We would need to see the line stats from the Billion.

It wouldn't even require line stats from each of the disconnections.
Just a single set of stats from the Billion would be enough to tell if the upstream was under any DLM limitations or of it was just a variable sync rate.

It's impossible to tell from a speed test if it's DLM related or not.

Thanks j0hn83

These are the stats

Model Name BiPAC 8800NL R2
Host Name home.gateway
System Up-Time 30D 16H 10M 35S
Date/Time Fri Sep 10 19:49:48 2021
Software Version 2.52.d15


Line Rate - Upstream (Kbps) 8595
Line Rate - Downstream (Kbps) 53451
Default Gateway / IPv4 Address ppp1.1 (DSL) / 86.139.252.xxx
Connection Time 4 Day(s) 19:14:25


Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 3.3 6.1
Attenuation (dB) 21.4 0.0
Output Power (dBm) 12.3 6.3
Attainable Rate (Kbps) 54725 8595

Rate (Kbps) 53451 8595

B (# of bytes in Mux Data Frame) 227 237
M (# of Mux Data Frames in an RS codeword) 1 1
T (# of Mux Data Frames in an OH sub-frame) 0 33
R (# of redundancy bytes in the RS codeword) 10 16
S (# of data symbols over which the RS code word spans) 0.1357 0.8793
L (# of bits transmitted in each data symbol) 14034 2311
D (interleaver depth) 4 1
I (interleaver block size in bytes) 238 127
N (RS codeword size) 238 254
Delay (msec) 0 0
INP (DMT symbol) 51.00 0.00

OH Frames 0 0
OH Frame Errors 19425 64
RS Words 3591931664 1886902782
RS Correctable Errors 235187720 418
RS Uncorrectable Errors 0 0

HEC Errors 0 0
OCD Errors 0 0
LCD Errors 0 0
Total Cells 3933999135 0
Data Cells 207320472 0
Bit Errors 0 0

Total ES 361 59
Total SES 269 0
Total UAS 401 136

Apologies for the formatting.

Does variable sync rate have a special meaning? 3.80 to 7.41 seems a lot of variance to me.

Regards

Paul

That looks quite a decent connection to me. 600-800 metres from the phone cabinet I expect, and add the distance between the FTTC and phone cabinets.

Given the SNR Margins, the interleave depth and the Delay (msec) I'd say DLM reckons it's a stable line. You are not getting sync speed changes.

Where are you seeing the term "variable sync rate"?

In reply to a post by BarkingMad:

3.80 to 7.41 seems a lot of variance to me.

The 3.80 looks like an outlier which could have been influenced by something outside your control or something within your own network. Outside your control could be glitches anywhere in the network. Within your control the most common cause for an outlier like that is something else using your bandwidth at the same time as the speed test. Was there anything else connected to the network apart from the machine doing the speedtest when the test was run? Anything which has any sort of automated backup to the Cloud or automatic download of updates could have caused a drop if that was running at the same time as the speed test. Was the test run from a machine connected by ethernet cable or WiFi? WiFi interference can also be a problem.

Take out the outlier and as Bob (Pluralist) says the line looks stable for both upward and downward connections. If DLM does kick in it will cause a disconnection and re-connect which re-sets the Connection Time shown in the stats so you can always check if you think you might have had a re-set.

Edited by GonePostal (Sat 11-Sep-21 09:25:17)

@pluralist,

It's around 600 metres to the cabinet. My connection is decent (currently) but sometimes my upload line rate drops. I don't have any saved evidence of the drop, apart from my speed test results - which is not ideal and I can see this is causing confusion. Sorry. I did confirm the line rate in the Billion and they followed the speedtest result dip.

I'm questioning why the upload line rate dips.

The "variable sync rate" term was a comment made by j0hn83

@GonePostal,

Thanks for your reply. I have shown speed test results because I have no other evidence of the line rate being lower. This is not ideal. I have caused confusion. Sorry.

When the line rate rate is lower, the speedtest results are lower. I did check the line rate in the router but I didn't save the evidence.

I'd like to know why my upload line rate dips.

Regards

Paul

The thinkbroadband BQM is an excellent tool for monitoring your connection.

Your Billion router supports it, but you possibly have a dynamic IP address seeing as you are with BT. In which case you should consider a Dynamic DNS service (DDNS) as explained if you click the link on that page for the complete BQM guide.

For help on DDNS you can wait and see if anyone posts here about it, as I have never needed to use one. AIUI it is very simple but there is a charge by the service.

In reply to a post by pluralist:

For help on DDNS you can wait and see if anyone posts here about it, as I have never needed to use one. AIUI it is very simple but there is a charge by the service.

First action is to find out which DDNS services are supported by the Billion router. Then either post the list here for a recommendation, or investigate each one yourself.

Variable upload line rate can point to a line fault, as this is normally affected the most. But, I wouldn't expect it to return to normal levels at any point, more a slower maximum speed (whilst the fault is present) with lower values on some resyncs. I wouldn't worry too much about the error counts, as such (particularly FECs). Just check to see if the line rate changes after a resync. I have had a BT Smart Hub 2 installed for a long time now, just because I used to get obsessed about error counts (the error counts are not visible with the BT SH2, and for a good reason).

Edited by Grimers (Sun 12-Sep-21 20:22:36)