[asterisk-users] Clocking Multiple T1 Cards

[Andrew Kohlsmith]

On Monday 24 July 2006 12:11, Shaw Terwilliger wrote:
> Thank you; this is the kind of information I was looking for.  The wiki
> and other documents told me exactly what the configuration options did,
> but I didn't know what kind of timing configuration was right for
> multiple cards.

Essentially the timing is ONLY for the hardware on the card.  The Digium cards 
use a quad framer chip (maybe a dual for the TE210 but I don't think so) and 
it's a hardware limitation of the framer that all spans must share the same 
clock source.  Sangoma's cards use individual framers and don't have this 
limitation.  (essentially I think it was a cost/space tradeoff.)

Once the data is on the PCI bus, the clock source is irrelevant.  They're all 
close enough that it doesn't matter anymore.  Those framers want exact 
lock-step timing though, which is why your clocking settings are so very 
important, and why with telephony in general it is crucial to think about 
your clocking before throwing hardware at a solution.

-A.