Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
   Compare ISP   Rate your ISP
   Glossary   Glossary
Please login or register.

Login with username, password and session length
Advanced search  


Author Topic: ZyXEL VMG 1312-B10A: Question about PhyR absent on upstream (again, groan)  (Read 295 times)


  • Addicted Kitizen
  • *****
  • Posts: 7256
  • Retd sw dev; A&A; 4 × 7km ADSL2; IPv6; Firebrick

I just read something that Kitz wrote a while back:

Certain equipment is not compatible with g.inp on the upstream. Those modems which can't do upstream G.INP were given a default profile that applied a high level of interleaving and Error Correction.

It was this high level of interleaving which caused the large increase in latency and Error Correction reduced the amount of available sync speed.

I apologise that I keep on obsessing  >:( ??? about why I don’t get PhyR upstream with this modem. I was just wondering if that article is relevant to an understanding of my situation or not.
  • I think Kitz’ article there was (confined to?) talking about VDSL2.
  • Do DSLAM designers have a means for dealing with one specific problem CPE modem model, making an exception for that model and changing behaviour, changing various parameters and disabling certain features selectively?
  • In my MSAN/DSLAM, is there a table that is indexed per-model and contains elements that are behaviour settings which controls the link set-up between DSLAM and CPE modem?
  • And if so, is it used for ADSL2?
  • I am wondering if I am understanding correctly when I got this ‘naughty list’ idea of per-model awareness vs settings into my head, model-sniffing if you will?
  • Is it possible that some MSAN/DSLAM has my ZyXEL VMG 1312-B10A modem on a naughty list for ADSL2?
I’m also wondering why the DLink DSL-320B-Z1s -which I was using this time last year- performed slightly better upstream compared with the ZYXELs, about 0-6% faster. A bit annoying, as I need all the upstream I can get.

[Warning, full of morphine tonight as pain was getting stupid earlier on. Under control now though, thank goodness.]


  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 26385
  • Over the Rainbow Bridge
    • The ELRepo Project

The device being written about was the ECI B-FOCuS /r . . . a locked-down (to modem-only mode) modem/router that Openreach provided and installed in the earlier days of the VDSL2 (ITU-T G.993.2) service availability.

Another rogue device is one of the earlier Asus modem/routers.

As for MSAN/DSLAM internal naughty-lists, I suspect the answer is no. But I cannot think of any reason why such a concept could not be implemented.
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.