Hi
Is the line attenuation of 0 db a reporting error ?
Regards jeff
Hi Jeff,
It's a firmware bug that is present in other devices that are based on the Broadcom 6368 VDSL2 chipset.
It is present because Broadcom hasn't updated the API between the webserver and the xDSL driver MIB for this particular chipset.
The webserver still looks to the MIB variables that were used to hold the ADSL2 attenuation measurements.
However, VDSL2 uses multiple upstream and downstream channels, (U0,U1,U2 and U3) and (D1, D2 and D3).
Somebody decided that a single (average) figure for line attenuation wasn't appropriate for VDSL2 since attenuation is frequency dependent.
But whoever built the Huawei firmware and specifically the middleware that sits between the webserver and the xDSL driver, didn't update the MIB references to point to the right MIB variables.
Broadcom's confidential source code for the ADS2+ driver was accidentally published last year, so you can get a good idea of what happens under the bonnet with the 63xx xDSL driver. Unfortunately, noone to date has leaked the source code modifications for VDSL2, otherwise the attenuation bug could be patched once and for all.
It's possible to hack together a patch by modifying the ASP code in the Huawei's web interface so that the attenuation figures for a VDSL2 connection are retrieved from a different source (from the response to a 'pbParams' request made to xdslcmd, a tool in the firmware). That's a bit of clumsy solution, though.
Cheers,
a