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Level 24: Supreme Being
Level 24: Supreme Being

NBN FTTN sudden increase in DSL link maximum speed

I checked my DSL link status yesterday as was surprised to see the download speed had increased by 30% (11 Mbps). The line attenuation, Output power and Noise margin has not changed. I have ready many post were the FTTN link has decreased is speed. I have seen no post were the link speed has increased. Has anyone else experienced an increase in speed on a FTTN connection. Does anyone know why the speed has increased.

 

DSL Link 37 MbpsDSL link 49 Mbps

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7 REPLIES 7
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Level 22: Superhuman
Level 22: Superhuman

Re: NBN FTTN sudden increase in DSL link maximum speed

@cf4 Mines normally around a Maximum Line rate of 20.03 Mbps up 35.43 Mbps down and an actual Line Rate of up 19.99 Mbps down 34.39 Mbps.

 

Currently its Maximum Line rate of up 13.92 Mbps down 39.81 Mbps and actual Line Rate of up 14.14 Mbps down 38.2 Mbps.

 

So its gone up, and never been that high.

 

Although my upload speed has dropped allot. (Which SamKnows is showing allot of movement)

 

 

 

Someone keeps putting vegetables in my beer crisper
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Level 20: Director
Level 20: Director

Re: NBN FTTN sudden increase in DSL link maximum speed

cf4 - Could be a statistical variance due to time of day or when the NBN network is in off-peak mode - more frequent samples over a longer period would validate the result. An upgrade or change of bandwidth allocation in the local node's DSLAM software may have occurred and a possible improvement in Gen 2 Modem's data processing capabilities due to the recent firmware upgrade.

 

I have always found Telstra Line Attenuation figures hard to comprehend, other modem suppliers publish one figure for Up and Down, Telstra modems show 5 for Up (U0,U1,U2, U3(N/A) and U4(N/A) and the 3 for Down - D0, D1 and D2. May be its the French supplier or how they list L.A. in Europe, but do you know what these figures represent as I assume the report is showing you one snapshot in time - Low, Average and High? - so why are there three figures so different for the UP and DOWN measurements? Which do you use?

 

The only variance I observed with your modem reading was in the UP fields - Noise Margin dropped in the UP by near to 2 dB and Line Attenuation U0 increased by 1dB. On the face of it, the DOWN benefited from these drops, but as I said it could be just statistical variance at play. Handy for you to track it continually for a while - perhaps NBN is starting to deliver on its promises. All the best.

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Level 24: Supreme Being
Level 24: Supreme Being

Re: NBN FTTN sudden increase in DSL link maximum speed


@Mkrtich wrote:

cf4 - Could be a statistical variance due to time of day or when the NBN network is in off-peak mode - more frequent samples over a longer period would validate the result. An upgrade or change of bandwidth allocation in the local node's DSLAM software may have occurred and a possible improvement in Gen 2 Modem's data processing capabilities due to the recent firmware upgrade.

 


The overall speed (Server to device) could be effected by congestion and a change in bandwidth to the node but Link line speed is purely dependent on the physical characteristics of the cable between the node port and the modem and also the performance of the modem and the node port. For the past year and a half the link speed using the Telstra Smart modem Gen 1.1 (DJA0230) has remained a constant 38 down and 12 up irrespective of time off. The only speed change occurred when the DJA0230 was replaced by a Sagemcom F@st 5355, the download speed increased to 40 Mbps but upload remained at 10. Since yesterday the link speed  has increased to constant 49 Mbps down and 13 Mbps up using the same DJA0230 modem. Overall Speed from connected device to server has increased from 35/11 to 45/12.

 


@Mkrtich wrote:

I have always found Telstra Line Attenuation figures hard to comprehend, other modem suppliers publish one figure for Up and Down, Telstra modems show 5 for Up (U0,U1,U2, U3(N/A) and U4(N/A) and the 3 for Down - D0, D1 and D2. May be its the French supplier or how they list L.A. in Europe, but do you know what these figures represent as I assume the report is showing you one snapshot in time - Low, Average and High? - so why are there three figures so different for the UP and DOWN measurements? Which do you use?

 


I interpretation is that the attenuation readings are taken at different frequency, U0 and D0 are the lowest frequency, U2 and D2 are the highest frequencies. The attenuation off a cable increases as the frequency increases which explains why attenuation of U0 and DO is less than U2 D2. The frequencies used in the upload direction are slightly lower than those used in downward direction.

 

https://uktechhub.com/forums/topic/understanding-vdsl-band-status-on-dsl-log-status-page-u0-u1-u2-d1...

 

 

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Level 20: Director
Level 20: Director

Re: NBN FTTN sudden increase in DSL link maximum speed

Thanks for unlocking the mystery of multiple L.A. figures. Both modems use the same BCM 63168 chipset for the CPU but the earlier one has less demanding supervision duties for its multi tasking functions such as Wi-Fi and LAN ports which may contributed to its previous higher marginal performance. Hope it stays at near to nominal speeds for you. 

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Level 24: Supreme Being
Level 24: Supreme Being

Re: NBN FTTN sudden increase in DSL link maximum speed

I think the reason for the increase in speed is that NBN Co has disconnected the cable leading back to the exchange. This would have removed a bridge tap. The effect off the removal of this bridge tap is clearly seen by comparing the present Bit loading graph to the bit loading graph before the increase in speed. On a normal DSL link the bit loading per tone gradually decreases as the tones increase in frequency. A bridge tap results in a notch in the bit loading graph were the bits per tone suddenly decrease and then increase.

 

Bit Loading Graph 38 MbpsBit Loading Graph 49 Mbps (Bridge Tap removed)

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Level 20: Director
Level 20: Director

Re: NBN FTTN sudden increase in DSL link maximum speed

Great diagnosis - is the graph display in the Modem or an external App?

I would have thought your jumper or double jumper (don't know how it is done, if previous co-existence arrangement ADSL2+/VDSL2+) at the pillar would have been removed when you went live on FTTN. Oversight may have discovered when another ADSL service was recently upgraded in your neighbourhood; don't know if Exchange MDF is disconnected or kept just in case. I have also read that NBN is upgrading feeder cables from FTTN Node to local pillars due to circumstances where they deem fit, so you may be been a beneficiary of that process as well. It's good to get nearer to nominal speeds. 

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Level 24: Supreme Being
Level 24: Supreme Being

Re: NBN FTTN sudden increase in DSL link maximum speed

There is a bit loading graph on Technicolor modems and Arcadyan modems at the bottom of the Advanced > Diagnostics > xDSL page.

I also thought they would have disconnected the cable running back to the exchange when I was cut over to NBN. The number on the exchange MF was disconnect as once cut over to NBN there was no longer 50 volt battery on my line.

My area has had NBN for over two years so there would no longer be any ADSL services connected to local exchange. I did receive a txt message from Telstra a few days before I noticed the increase in speed warning that my service could be interrupted due to NBN outage. NBN co might be in the process of disconnecting all the redundant cabling.

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