[Asterisk-Users] T100P / ZAP / PRI errors

[dpobanz at hastingsutilities.com]

Quoting willy at yponeinc.com: 
 
> Now you've got me utterly confused ... 
> So, in layman's terms, if I connect a T100P to a circuit 
> provided by the Telco, and the Telco says that they will 
> provide timing, I have to put WHAT? 
> span=1,0,0,esf,b8zs,yellow  
> this means '0' this span is not a sync source, i.e. the 
> Telco will provide my 8kHz.  Could one use '2' with impunity 
> (span=1,2,0,...)? I am still not clear under which 
> circumstances one should use '0' versus '2'. 
> WW 
 
There are 3 choices for T1 timing, regardless what the timing is called.  
 1. internal (run off of an internal clock) 
 2. external (an external clock is input for timing only) 
 3. loop (timing is derived from a traffic carrying T1) 
 
To my knowledge, Digium hardware does not support external timing (like from 
an atomic clock) so that leaves internal or loop.  
 
In this case you want to use loop timing (use the T1 as a sync source) so,   
 
span=1,1,0,esf,b8zs 
 
Don Pobanz 
 
I know, I just restated what Andrew said. He was correct ;) 
 
> > We need to get this documented *clearly* once and for all. 
> >  
> > Zaptel T1/E1 hardware either free-runs to its own internal 
> > 8kHz time source,  or it tries to lock to the recovered 
> > clock from the line. 
> >  
> > Zapata.conf says that timing of 0 means "do not use this 
> > span for timing."  Zero does not mean "slave timing", it 
> > means not to use this span as a  recovered clock source 
> > for timing at all.  Timing values of 1 or 2 mean try  to 
> > lock the internal clock to the recovered clock from the 
> > span. 
> >  
> > A value of 0 means that this span's recovered clock never 
> > gets used as a  timing source.  A value of 1 means that 
> > this span is the primary clock source  -- If the span is 
> > up, try to lock the internal clock to the clock recovered  
> > from this span.  A value of 2 means to use this span for 
> > timing only if the  primary span is down. 
> >  
> > To reiterate: a value of 0 means that the other end must 
> > be locking to the  zaptel's clock or else clock slips will 
> > occur. 
> >  
> > Feel free to correct me if I'm wrong, but I am pretty sure 
> > I have this  right.  :-) 
> >  
 
You have it correct!  
 
> > Regards, 
> > Andrew 
>  
> Willy Wouters 
> ypOne Publishing 
 

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