Help me understand line sync speed

[Werfetter]

Hi Guys,

Sorry if this has been asked before, if so please just direct me to the right place.

Can someone help me understand how the line speeds are determined. For example, I can see the following on my router:



My question is with regards to the Data rate (2560kbps) in the above picture. This number has been consistent so I am assuming it is a configuration item as it never changes (even with router restart). That number also accurately reflects the speeds I get on speed tests. Where I am unclear:

1. How is this number determined
2. How does "Max Rate" relate to the "Data Rate"

I am paying for a 4mbps line at the moment and as far as i can see that is not the rate a 4mbps line should be "syncing" at?

Please feel free to correct any terminology or incorrect understand in the above...

 

[Mr.Jax]

That is certainly strange.

Data Rate is your current sync speed. Max Rate is what your DSL modem thinks (given current state of attenuation and SNR) is achievable. Its usually slightly higher than what's achievable.

However,

Your downlink SNR Margin is at 7 which is a bit low and could be the reason for it not achieving the full 4Mbps. But, it is strange, since the modem reports a max rate of ~7Mbps....

I think this (7dB SNR) is because of the ASSIA system Telkom uses (it auto-tunes DSL lines for max stability)..I've seen this before when I still had a DSL line.

Maybe give telkom support a call and ask them to recreate your port and to verify that you are indeed on a 4Meg sync profile, because that does suspiciously look like a 2Meg sync profile to me (many users on 2Meg reported that their lines are sync'ing at ~2.5Mbps; the general consensus is that Telkom does this to mitigate the DSL overhead which is significant).

 

[Werfetter]

That is certainly strange.

Data Rate is your current sync speed. Max Rate is what your DSL modem thinks (given current state of attenuation and SNR) is achievable. Its usually slightly higher than what's achievable.

However,

Your downlink SNR Margin is at 7 which is a bit low and could be the reason for it not achieving the full 4Mbps. But, it is strange, since the modem reports a max rate of ~7Mbps....

I think this (7dB SNR) is because of the ASSIA system Telkom uses (it auto-tunes DSL lines for max stability)..I've seen this before when I still had a DSL line.

Maybe give telkom support a call and ask them to recreate your port and to verify that you are indeed on a 4Meg sync profile, because that does suspiciously look like a 2Meg sync profile to me (many users on 2Meg reported that their lines are sync'ing at ~2.5Mbps; the general consensus is that Telkom does this to mitigate the DSL overhead which is significant).

This is what I was suspecting, what really annoys me is I spoke to my service provider and was told the line is synced like this because of congestion on the exchange and it should return to normal as soon as congestion reduces (it does not). This does not sound quite right to me? Congestion would reduce available bandwidth and in increase my latency but I have no latency or throughput issues?

 

[Werfetter]

Right so Telkom recreated the port at the right speed and it is working as well as it ever has. Two calls to my ISP could not resolve this with them just blaming congestion.