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[mbrijun]

Looking for some help with interpreting the line statistics from my Vigor 130. The modem was reset to factory defaults less than 24 hours ago. This can be seen from the "showtime" - 69731 seconds of line activity. However, interestingly I have several day's worth of Forward Error Correction Seconds (FECS) - 170595 seconds on the upstream. How is this possible? A bug in the firmware (I am using the latest available firmware 3.8.5.1-BT), or a feature? Is there a way to reset the counter to zero to see how my line is actually doing?

Code: [Select]

> vdsl status counts
vdsl status counts
 [ Counters: Showtime ]
                  Near End        Far End    Note
 ElapsedTime  :   69731            69731 (seconds)
 CRC          :    134            12841
 FEC          :   56643            170595
 HEC          :      0               0
 CRC_P        :      9               0
 CRCP_P       :      0               0
 CVP_P        :      0               0
 NCD          :      0               0
 LCD          :      0               0
 ES           :      7            12254
 SES          :      0              21
 LOSS         :      2               0
 UAS          :      0               0
 LOFS         :      0               0

 [ Counters: 15Min ]
                  Near End        Far End    Note
 ElapsedTime  :    737             737 (seconds)
 CRC          :      0               0
 FEC          :    354               0
 HEC          :      0               0
 CRC_P        :      0               0
 CRCP_P       :      0               0
 CVP_P        :      0               0
 NCD          :      0               0
 LCD          :      0               0
 ES           :      0               0
 SES          :      0               0
 LOSS         :      0               0
 UAS          :      0               0
 LOFS         :      0               0

 [ Counters: 1DAY ]
                  Near End        Far End    Note
 ElapsedTime  :   79937            79937 (seconds)
 CRC          :    134            12841
 FEC          :   56643            170595
 HEC          :      0               0
 CRC_P        :      9               0
 CRCP_P       :      0               0
 CVP_P        :      0               0
 NCD          :      0               0
 LCD          :      0               0
 ES           :      7            12254
 SES          :      0              21
 LOSS         :      2               0
 UAS          :      0               0
 LOFS         :      0               0

> vdsl status more
vdsl status more
  ---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------
                  Near End        Far End    Note
 Trellis      :      1               1
 Bitswap      :      1               1
 ReTxEnable   :      0               0
 VirtualNoise :      0               0
 20BitSupport :      0               0
 LatencyPath  :      0               0
 LOS          :      2               0
 LOF          :      0               0
 LPR          :      0               0
 LOM          :      0               0
 SosSuccess   :      0               0
 NCD          :      0               0
 LCD          :      0               0
 FECS         :   56655            170595 (seconds)
 ES           :      7            12254 (seconds)
 SES          :      0              21 (seconds)
 LOSS         :      0               0 (seconds)
 UAS          :     28            30350 (seconds)
 HECError     :      0               0
 CRC          :    136            12841
 RsCorrection :      0               0
 INP          :      0              20 (symbols)
 InterleaveDelay :      0            1600 (1/100 ms)
 NFEC         :    254             128
 RFEC         :     14              16
 LSYMB        :   2191            14128
 INTLVBLOCK   :    127             128
 AELEM        :      0            ----
>


[RealAleMadrid]

@mbrijun
 I have always found the Draytek Vigor line stats confusing but from this link https://www.draytek.co.uk/support/guides/kb-dsl-status-more Far End data refers to the Upstream direction and FECS are forward corrected errors not error seconds. Also as they are reported on the upstream the values come from the exchange DSLAM so the values do not get reset when the modem is reset but keep incrementing, giving accumulated values over time.

Your downstream figures look good and as FECS are corrected errors there's nothing to worry about, are you having problems with the broadband performance?

[mbrijun]

@RealAleMadrid

Thank you for your reply. I recently changed my ISP, and they asked for the Technicolor DWA0120 to be sent back. I have used the DWA0120 for well over a year with very good results. This might be because both the Far and Near end were based on Broadcom chipset. With the DWA0120 out of the picture, I switched to a Vigor 130 which was very affordable on eBay. During the first evening, when I was streaming films, the connection started dropping with alarming regularity.

I managed to stabilise the connection by forcing a switch from the "fast" mode to the "interleaved" one. To achieve this, I disabled G.INP on the Vigor. It has been stable ever since. However, in the process I noticed a large number of errors on the upstream side. I think what you are saying about that coming from the cabinet, makes a good sense. That would definitely explain the large numbers.

With regards to FECS, I suspect they are seconds, after all. If I do "vdsl status more", it reports the unit of measurment as "seconds" next to FECS. It kind of makes sense, if you think of it. FECS is a proactive mechanism, and I suspect the sending end does not really know if the redundant data/checksums have been used by the receiving end or not. For that reason, it simply reports "I have been sending redundant data for X number of seconds".

Code: [Select]

> vdsl status more
vdsl status more
  ---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------
                  Near End        Far End    Note
<...>
 FECS         :   56655            170595 (seconds)
 ES           :      7            12254 (seconds)
 SES          :      0              21 (seconds)
 LOSS         :      0               0 (seconds)
 UAS          :     28            30350 (seconds)
<...>


[Alex Atkin UK]

Remember they are counters though, so its seconds out of the entire uptime for Near End - and seconds since records were last reset on the DSLAM Far End.  So unless its visibly going up constantly, it does not represent an active problem.

[RealAleMadrid]

@mbrijun 

As I said in my previous message the FECS value is count of corrected errors, it is NOT seconds The Draytek document and the modem stats display are incorrect.

My modem (Huawei HG612 ) reports this for the latest 15 minute interval....
Latest 15 minutes time = 14 min 23 sec
FEC:            628516          0
CRC:            0               1
ES:             0               1
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0

Fifteen minutes is 900 seconds, see what I mean?

I would strongly suggest replacing the Vigor 130 with a Broadcom based device. There are many reports of problems with the Vigor 130 on lines with a Broadcom DSLAM,  it seems they don't work well together.

You say you disabled G,Inp to make the line more stable, on a VDSL2 line G.Inp is a very good thing if it's working properly so it also suggests that the Vigor in not doing very well on your line.

I must admit I have never liked the Vigor modem, the jumbled up stats display and errors in the text are a real turn off, and they don't work well on a lot of lines.

On the Other hand my Huawei HG612 3B with updated firmware to access the stats has been excellent for years, others warn of the age and it's likely to fail but if it ain't broke there's no need to fix it.

[Edinburgh_lad]

@Alex Atkin UK

There's no problem with running a modem with a different chipset on a Broadcom DSLAM. I think there's a problem with Draytek products in general in that they don't handle noisy lines well, or maybe it is lines with Broadcom indeed. That's my experience of using a couple of Drayteks on my noisy line (when I had it) and then using Fritzbox (Infineon) and Zyxel 8924 (Broadcom), both of which performed to the same degree.

[mbrijun]

I have mixed feelings about the whole situation.

• Internet should be based on open standards. For that reason, there should be no situation where the equipment from vendor A does not work well with the equipment from vendor B. Accepting that one must have matching chipset vendors on DSLAM and the modem would be a defeat of sorts.
• It is a possibility that the Vigor 130 is not nececcarily "bad" at handling slow, noisy lines. Perhaps it is simply bad at "masking" real problems, such as over-reliance on error correction.
• If I am not mistaken, G.INP was invented by Broadcom in the form of PhyR ("fire"). For that reason, I would not be overly surprised if they have some "secret sauce" in their implementation which makes it works "best" between two Broadcom devices.
• G.INP is based on a very opportunistic approach to comms - shooting packets across as fast as possible, and relying on a sizeable cache on the sender's side for when things go wrong. On the other hand, "interleaved" method is a conservative, safe approach. If I had to choose between a car that is slower yet reliable and the one that is fast, fails often and can be fixed cheaply, I would choose the former without hesitation. Increased latency is not really an issue, as I am not a gamer. Behind the modem there is a router with OpenWRT installed which also runs a Smart Queue Management (SQM) script to prevent Bufferbloat - on a relatively slow line like VDSL this is arguably one of the most important things to take care of.
• The Vigor 130 has a tweak that allows increasing the desired SNR margin. Just like G.INP, wafer-thin SNR margins is another overly opportunistic approach to comms. Pretty much like reving an engine close to the red line.
• I think that the CLI of Vigor 130 is a bit arcane and inconsistent in places. On the plus side, Draytek publish regular updates to their firmware, which cannot be said about many other vendors.

[Alex Atkin UK]

They do work to a standard, but how they achieve that standard may differ.  Its the nature that implementations can have different strengths/weaknesses to each other and these will naturally be more apparent on more problematic lines.

We have the same problems with WiFi, some implementations just don't work nicely together, even though they should.  There may be bugs, or poor components choices/circuit designs that only show up in niche circumstances.  Its sadly the nature of how complicated the technology is.

[tubaman]

G.INP can work very nicely indeed, it certainly does on my line and increases the line rate from around 36Mbps to 42Mbps. It does this running at 3dB with very low error rates. Unfortunately as you have found not all DSL modems are the same. My Broadcom line runs at it's best using a Zyxel VMG8924-B10A (I suspect a VMG1312-B10A would work equally well). I have tried a multitude of others courtesy of eBay and nothing syncs as fast or as reliably. Other's have different experiences but certainly on this forum those particular two devices are very much liked albeit getting quite old now.

[Edinburgh_lad]

@tubaman Does the difference of 6Mbps make a real difference? I couldn't see much of a difference between 50Mbps and 70Mbps on my line, to be honest.

@mbrijun the DrayTek of today has a lot of problems with their firmware - check their forum - and while it's regularly released, I must say it's to fix problems, if at all. I'd not buy a DrayTek again.

Re this 'secret sauce': is this a speculation or evidence based? With modern ways of reverse engineering and more accessible Broadcom drivers, how secret is this sauce, whatever that means, actually.

[mbrijun]

@RealAleMadrid - I now finally see your point about FEC vs. FECS. "vdsl status more" and "vdsl status counts" disagree with each other on whether FEC/FECS it is a count of instances or a number of seconds.

@Alex Atkin UK - I agree with you that there is plenty of opportunity to introduce suboptimal circuit designs or software bugs in the firmware, all of which would decrease the stability of the finished product.

@tubman - it is very tempting to buy more IT equipment, but I must resist the temptation! I wonder if anyone here has tried cisco C880 series devices, such as C887 which can be had for less than £25 on ebay.

@Edinburgh_lad - my thoughts about "secret sauce" is pure speculation. It might be my negative bias due to Broadcom making headlines that are less than flattering.

[tubaman]

@tubaman Does the difference of 6Mbps make a real difference? I couldn't see much of a difference between 50Mbps and 70Mbps on my line, to be honest.
...

When there are two of us working from home and two younger ones streaming stuff then every little bit helps as they say. 

[mbrijun]

@tubaman - this is what Smart Queue Management ("bufferbloat") should *really* help with.

[Edinburgh_lad]

@tubaman and @mbrijun or introducing broadband access quotas. This can be enabled on Draytek: a welcome screen with a user having to enter a code to gain access: https://www.draytek.co.uk/information/our-technology/hotspot-portal. Good for children to get a code once they've done the dishes etc.

By the way, the new Fritzbox 7530ax (as supplied by Zen, for example) is Broadcom through n through if anyone must obsess to have a matching chipset. Fritzbox 7590ax has an Infineon chipset.