[asterisk-dev] E1 CAS dchan=16 [was: Re: [svn-commits] kmoore: tools/trunk r9485 - /tools/trunk/xpp/perl_modules/Dahdi/Config/Gen/]

[Moises Silva]

On Thu, Nov 18, 2010 at 8:35 AM, Will <nyphbl8d at gmail.com> wrote:

> On Wed, Nov 17, 2010 at 10:24 PM, Tzafrir Cohen <tzafrir.cohen at xorcom.com>wrote:
>
>> Hi,
>>
>>
>> Before the change, the following configuration would be generated for a
>> span (in this case: channel for span 1)
>>
>> cas=1-15,17-32,1101
>> dchan=16
>>
>> That second line was added later on as I noticed that without it some
>> things break (things to do with the 16-th time slot. I'll try to figure
>> them out later).
>>
>> Could you please elaborate on the bug DAHDI-763 ?
>>
>> --
>>               Tzafrir Cohen
>>
>
> Tzafrir,
> When configurations were generated for MFC/R2 links, the dchan line would
> generate an error since (as of rev 9056) signaling is not allowed to be set
> on channel 16 of E1 CAS lines because it is reserved for robbed bit data.  I
> added this restriction in the single, dual, and quadspan drivers to ensure
> the channel can not be overwritten accidentally, but I apparently neglected
> the xpp drivers. Would you agree that channel 16 should never be directly
> written to when in E1 CAS mode?
>
>
Thanks for this, finally consistent configs. I remember some versions of
zaptel/dahdi accepting or even requiring dchan=16 and others don't (it seems
at some point was put back). I can agree dchan=16 does not make any sense in
E1 CAS mode and should not be accepted ever again :-)

Moises Silva
Senior Software Engineer
Sangoma Technologies Inc. | 100 Renfrew Drive, Suite 100, Markham ON L3R 9R6
Canada
t. 1 905 474 1990 x128 | e. moy at sangoma.com
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