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6608 Module Internal vs. SpanX Clocking

I have a 6608 module (w/Call Manager) with 2 PRI's to the PSTN and 2 PRI's to an I3 Call Center server. The I3 box wants clocking from the "network" so I have the 6608 port clocking set to "internal". The 6608 ports to the PSTN are "network" clocked. I'm experiencing intermittent dropped calls to/from the I3 box and suspect clocking problems. The question: When a 6608 gateway port is configured for "internal" clock, where is that clock derived from? An internal oscillator or the PSTN? I think I want to synchronize everything off of the PSTN clock. Would this be achieved by selecting "SpanX" clocking for the I3 PRI's? "SpanX" being one of my PSTN PRI's. The TAC cannot tell me what the "Span1...8" option is within Call Manager or where the "internal" clock is derived from.

Cisco Employee

Re: 6608 Module Internal vs. SpanX Clocking

I am reasonably certain that using "internal" would generally only be done if there are no circuits connected to the card where a clock is already being derived. In your case, I would set the clock for the circuits connecting to I3 to "SpanX" which will use the derived clock from the selected span.

Community Member

Re: 6608 Module Internal vs. SpanX Clocking

Thanks for the response. About a week ago I set the clocking for the PRI's to the I3 to SPAN1 (which is connected to the PSTN) and my dropped calls appear to have gone away.

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