Andrew Kohlsmith wrote:

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.

This statement is very very wrong. The timing matters enormously. If the timing doesn't match, there will be frame slips, and things like modems will not work. The snag is, right now neither Asterisk or the cards it uses have the ability to lock their clocks together.

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.
Steve

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