Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
   Glossary   Glossary
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Author Topic: VDSL2 DS Throughput Ratio Observed Changes  (Read 492 times)

tiffy

  • Reg Member
  • ***
  • Posts: 846
VDSL2 DS Throughput Ratio Observed Changes
« on: January 09, 2020, 06:11:45 PM »

Have noted "recent" changes on the 3 VDSL-2 lines I monitor, with respect to DS throughput ratio, 2 X Plusnet 40/10 and one BT 80/20 lines, all on different Huawei DSLAM's, same exchange.
All 3 lines are running on DS Re-Tx low profile as verified by Bearer 0 INPRein being "zero".

With Re-Tx low profile, throughput ratio on all lines has always been close to 97% as calculated:
(DS BRAS Profile/DS Synch Rate*100)

Certainly since the DSLAM firmware update which occured on the 10/12/19, quite possibly before that date, have noted that all 3 lines now produce exactly the same DS TP ratio of 92.11% a rate that would previously have been close to expectation with Re-Tx high profile.

There have been a few recent posts noting a similar scenario.

As my 3 monitored lines are exibiting virtually identical characteristics with respect to this parameter, wondering if there has been a recent change in DSLAM operating parameters/policy by OR/BTw.   
Logged
Plusnet 40/10 - DSLStats/RPi3B - ZyXEL VMG1312-B10A Modem/VMG-3925-B10B Router Huawei Cab

tommy45

  • Reg Member
  • ***
  • Posts: 604
Re: VDSL2 DS Throughput Ratio Observed Changes
« Reply #1 on: January 14, 2020, 09:04:05 PM »

Have noted "recent" changes on the 3 VDSL-2 lines I monitor, with respect to DS throughput ratio, 2 X Plusnet 40/10 and one BT 80/20 lines, all on different Huawei DSLAM's, same exchange.
All 3 lines are running on DS Re-Tx low profile as verified by Bearer 0 INPRein being "zero".

With Re-Tx low profile, throughput ratio on all lines has always been close to 97% as calculated:
(DS BRAS Profile/DS Synch Rate*100)

Certainly since the DSLAM firmware update which occured on the 10/12/19, quite possibly before that date, have noted that all 3 lines now produce exactly the same DS TP ratio of 92.11% a rate that would previously have been close to expectation with Re-Tx high profile.

There have been a few recent posts noting a similar scenario.

As my 3 monitored lines are exibiting virtually identical characteristics with respect to this parameter, wondering if there has been a recent change in DSLAM operating parameters/policy by OR/BTw.   
Interesting , has your Target DS SNR lowered to below the default 6db,? as if it has dlm may have also applied the retx as a precaution to counter instability? That's what it did to my line, when it reduced the SNR to 3db, and then removed soon after but the Bras IP profile remained set at 92% approx I have had zen support chase BT on this they have in their reply basically admitted  being aware of this "slight issue"
Quote
we are aware there is a slight issue with the calculations on the bras server of around 5% and this is currently under review. However the majority of circuits meet or surpass their minimum expected requirement. This circuit meets those requirements.
Now where they talk about meeting requirements they are talking about the minimum throughput level handback threshold  it would have to fall to before they regard it as a fault, that bt bod imo was talking at cross purposes
Logged

tiffy

  • Reg Member
  • ***
  • Posts: 846
Re: VDSL2 DS Throughput Ratio Observed Changes
« Reply #2 on: January 15, 2020, 10:27:54 AM »

@tommy45

Quote
Interesting , has your Target DS SNR lowered to below the default 6db,? as if it has dlm may have also applied the retx as a precaution to counter instability? That's what it did to my line, when it reduced the SNR to 3db, and then removed soon after but the Bras IP profile remained set at 92% approx I have had zen support chase BT on this they have in their reply basically admitted  being aware of this "slight issue"

All 3 lines have always had DS Re-Tx (G.Inp) active and have always been "low profile".
DS target SNRM is 3dB on one of the PN 40/10 lines and the 80/20 BT line for as long as I remember.
The other PN 40/10 line has always had a considerably higher DS target SNRM, high subscriber density area, lots of cross talk, noisy line.

After the DSLAM's outage event on 10/12/19, all DS & US SNRM's dropped considerably and remained so until the next re-synch's.

The point I'am trying to make, brobably rather badly, is why has DS Synch/IP profile ratio changed to the value that would have been expected with Re-Tx high profile until very recently while all 3 lines remain on Re-Tx low profile.

Noted that there has been a further DSLAM event this morning at approx 02:00 hrs., all 3 lines have re-synch'ed to more or less normal expectation, DS Re-Tx low profile still applied, have not yet checked if any IP BRAS profile changes have occured. 
Logged
Plusnet 40/10 - DSLStats/RPi3B - ZyXEL VMG1312-B10A Modem/VMG-3925-B10B Router Huawei Cab
 

anything