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[bilbokitz]

I am trying to understand if vpi vci settings are needed for vdsl or not? Reading around I understood not but the provider here (IoM) lists them as requirements per the attached.

Are they needed? Does atm still come into a vdsl connection?

[bilbokitz]

Also I found an openwrt config on the net where this is listed in the network file for a fibre connection

Code: [Select]

config interface 'adsl_wan'
        option type 'bridge'
        option ip6hint '0'
        option force_link '0'
        list ifname 'eth4'
        list ifname 'eth3'
        list ifname 'atm_0_38'
        list ifname 'ptm0'
Note the atm_0_38

[j0hn]

VPI/VCI can be used with VDSL, but only with VDSL over ATM.
It's not used/needed with VDSL over PTM.

I can't even set VPI or VCI if I chose PTM.

[Weaver]

There is no ATM with VDSL2 as deployed hereabouts so there is no such thing as VPI / VCI _in reality_. Of course some user interface things may be generic, so they may show such settings as a hangover. We use the PTM protocol as an alternative to ATM.

So the answer to Bilbokitz is a ‘no, there's no such thing (effectively)’.

Or: Have I gone mad?

[Weaver]

And btw @bikbokitz VDSL2 cannot be used with fibre internet access to your premises, only applies to copper, it's just a lie from the marketing men.

[bilbokitz]

The reason for the question is that I had been struggling to get a new modem to bridge properly which I have managed by adding said setting in the second post (although I changed other things as well and need to confirm which one it was) and I was wondering why this was given what I know about VDSL.

I dug up an old post of my own in which I was trying to get the hg612 to work and apparently the atm is definitely relevant to me it would seem.

http://forum.kitz.co.uk/index.php/topic,13435.msg253262.html#msg253262..

"The magic setting was to fill out the atm section vpi vci to 0 38 with vcmux"

Needed but does it do anything I wonder?

Out of curiosity  , can someone else with a bridged hg612 say if they have anything set on the atm section?

ifconfig on the modem shows the ptm0 interface, no atm however.

[j0hn]

There is no ATM with VDSL2 as deployed hereabouts so there is no such thing as VPI / VCI _in reality_. Of course some user interface things may be generic, so they may show such settings as a hangover. We use the PTM protocol as an alternative to ATM.

So the answer to Bilbokitz is a ‘no, there's no such thing (effectively)’.

Or: Have I gone mad?

You can have VDSL over ATM.
Bilbokitz uses an Isle Of Man ISP who likely deploy things different to OpenReach.

I've always been under the impression that VPI/VCI settings were an ATM thing. Looking again online I can see EE recommending similar settings for their FTTC.

If I set PTM it greys out or completely hides VPI/VCI settings.

[ejs]

You can in theory have VDSL2 using ATM, but I gather nobody actually does (ATM would only give higher overheads). The settings in the screenshot say PTM.

[bilbokitz]

Yes I am on ptm, I am inclined to think that the vci vpi settings supplied by the provider are a red herring, I can see looking at the wan section under basic on the hg612 it is set to ptm so I don't think the atm settings under basic should make any difference. Hmm I wonder why I thought this was the case previously. 

I might try changing the atm section and plug the hg612 back in as a test and see if I get a connection.

[Weaver]

I am aware that ATM exists in the standards, but it will not be supported in reality here. Ellan Vannin is another thing for all I know and if they want to simply throw 10% speed away for absolutely no reason at all then that is up to them.

J0hn is right, there is no such thing as VCI VPI apart from within ATM. They are ATM-specific concepts and will have no effect or relevance unless you do have this foreign theoretical VDSL-over-ATM service.

[burakkucat]

[off topic]
But it may be of very minor interest to Weaver . . .

Anyone who has set up one of the ZyXEL VMG1312-B10{A|D} devices (and possibly other ZyXEL devices, as well) will have see a setting under the "ADSL Modulation" heading of an option for "PTM over ADSL".
[/off topic]

[Weaver]

[off topic]
Ooh. The reverse of the current topic! If memory serves, Burakkucat and I were talking about this some while ago, and Burakkucat might have even discussed trying it out for me back then. That was for G.992.3 with PTM. If only PTM were actually supported by BT or Talktalk over ADSL2 then  it would be fantastic for us troglodytes as it would instantly get us back the wasted 10% of speed (>53/48 slowness factor) that we have simply lost with the madness of ATM. The ATM slowdown will be far far more than that if sending / receiving short messages, in fact easily 50% speed reduction.
[/off topic]

[bilbokitz]

Thanks for the replies, it is nice to start a discussion and increase my understanding.

I have come to the conclusion that those vpi/vci settings are a red herring and indeed VDSL here does not use ATM, that would be daft.

Using a router I have at work I put some random vci vpi settings in and the VDSL works just fine.

[licquorice]

Although VPI/VCI have no relevance with PTM, I seem to remember there was a problem reported on the BT forum with a Fritzbox that wouldn't connect to VDSL unless VPI/VCI was configured despite being irrelevant!!

[burakkucat]

. . . I seem to remember there was a problem reported on the BT forum with a Fritzbox that wouldn't connect to VDSL unless VPI/VCI was configured despite being irrelevant!!

Although I did not read it first hand, I recall that was discovered and mentioned. Logically we can say that is the result of poor coding of the software controlling the Fritzbox in question.