Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: roseway on July 15, 2015, 08:03:01 AM
-
At about 00:30 today my connection dropped for a few minutes and then came up with connection speeds of 79999/19999 (previously 77934/19999). Some of the G.INP settings have changed a little, and in particular the downstream bearer 0 interleave depth has increased from 8 to 16. The downstream SNRM has dropped from 6 dB to 5 dB, and the attainable downstream speed has increased to over 80000 currently.
Previously the connection was totally stable and the ES levels were only about 6 ES per hour. So it looks like a bit of G.INP optimisation, although I have no idea what initiated it.
None of this has any significant practical consequence for me, but it's a curiosity, and it would be interesting to work out what's happened.
-
well you have to consider the extra attainable may just be down to the reduced snrm.
given how good g.inp is really they should be able to roll this thing out with a 4db snrm target.
-
Can you tweak the SNRM on FTTC? This would give an insight into the performance of G.INP on that target.
-
No, but you can limit the sync speed
-
Yes you can, but I don't think I'm very inclined to do it at present.
-
It looks like your interleaving level increased because your INP level dropped slightly.
When I had my weekend of power outages, I noticed the INP level increased a few times ... and the interleaving level fell at the same time. I'm not sure what happened to the interleaving block size though - it might have adjusted to compensate.
When DLM relented a few days later, INP went back down, and interleaving went back up.
In all respects, I'm talking about bearer 0.
-
That sounds quite probable, but what triggered it? Would this be a normal DLM intervention?
-
Funnily enough, I also had something happen to my line over night, changes that kicked off at 00:30 this morning too!
See attached TBB trace.
What's weird is that my dsl stats are now reporting some weird figures. Seems that my max and bearer 0 figures have swapped... ???
xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 15326 Kbps, Downstream rate = 61212 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 70439 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 4.6 4.7
Attn(dB): 18.1 0.0
Pwr(dBm): 14.0 7.4
Speed test confirms all good (around 64MB download speed: http://www.speedtest.net/my-result/4507029306 (http://www.speedtest.net/my-result/4507029306)) so all good... Definitely not complaining !
-
Apol for my ignorance of VDSL and g.inp etc. What is bearer 0, 1 etc?
-
What's weird is that my dsl stats are now reporting some weird figures. Seems that my max and bearer 0 figures have swapped... ???
That's probably due to SNRM being low at 4.6dB/4.7dB.
They were probably at around the target 6dB when the connection initially synced, but have reduced as time went on, thus significantly lowering attainable (Max) rates.
-
Apol for my ignorance of VDSL and g.inp etc. What is bearer 0, 1 etc?
I'm pretty ignorant myself, but briefly, Bearer 0 and 1 are two channels of information carried over the VDSL2 connection. Bearer 0 is the main data channel, and Bearer 1 has the G.INP error correction.
-
@roseway at first glance that makes no sense at all from a protocol design point of view. But...
maybe it's a really clever way of handling backwards compatibility. Historical precedent.