Help & Support

What is TBF and how it can be launched

TBF (Test de Bonne Fin) is a process that is designed to verify if there is a possible technical issue on a VDSL2 line and to determine the best applicable profile.

How does it work?

When started, TBF applies a provisioning profile (this will result in a short disconnect) and starts monitoring the line quality, stability and performance, which may last up to 6-8 days.

  • If TBF detects a fault on the line or the latter happens to be unstable, a repair profile, with the maximum speed of 9 Mbps down and 0,5 Mbps up, will be applied.
  • If a non-certified modem is installed, the line will be downgraded to a fall-back profile, with the maximum speed of 7 Mbps down and 0,5 Mbps up.

If none of above-mentioned scenarios applies, the line will be put on the provisioning profile. Learn what speed profile is to be applied to your line, depending on whether the street cabinet, on which the line is connected to, already equipped with vectoring-ready VDSL cards. The monitoring process will then continue in order to ensure the assigned profile does not cause any transmission errors or instability. Otherwise, the line will be downgraded to a repair profile.

If TBF is successful, it also triggers DLM, the process allowing VDSL2 lines to benefit from higher bit rates than expected according to the provisioning rules (up to 100 Mbps).

When is it launched?

First TBF gets automatically launched as soon as VDSL line is activated. If no modem is installed at that moment, TBF will fail and will need to be restarted.

All further TBFs are to be manually launched. The process can be performed if the current profile does not seem to be optimal:

  • when the line is for some reason not on provisioning profile (for instance, if the first TBF failed or if vectoring has been activated at the street cabinet level only after line activation)
  • when the line should be out of a repair profile, provided that the issue which caused it to be applied has been resolved
  • when the line should be out of a fall-back profile, provided that a certified modem has been installed.

What about DLM?

TBF triggers DLM, but unlike the latter, it will never upgrade the line to a profile higher than the provisioning one. If TBF is launched on the line which speeds are already boosted by DLM, the process will normally leave DLM running and will only trigger its new evaluations.

Great, how can I launch it?

Just contact us at 03 265 67 00, we will start a TBF and will follow up with you.

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