T3 timing - clock source

not sure if this is the right place to ask this but, recently I was talking to a VZ data tech and we started talkign about timing and i told him that i used line timing for my custermers end and on the t1. I told him that i had my t3 set to looped (line) timing, this is when he told me that this could cause issues and i should set it to internal timing. as my t3 should be the master clock for all my t1s on it.

Im using a cascade switch to terminate my t3's from VZ. He told me that the t3's should provide their own timing.

just wondering if this is the right thing to do, setting it to internal timing.

we are running a frame-relay network and get point to point t3's from vz


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Brad Reese BradReese.Com - Cisco Salary and Compensation Rates

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I'm not following you that closely.

You have a T3, terminating some PtP T1s from some remote sites. Presumably the T3 terminates at a Verizon DACS somewhere?

Your T3 MUX/switch should probably recover the timing at the T3 layer from the far end (ie. the loop) as the DACS is probably set to provide clocking on the T3 port.

The T1s inside the T3 won't be clocked from anywhere (they don't by default get their clocking from the T3 carrier they ride), and most likely your switch will only deal with recovering one or a few clocking sources at the T1 layer, so it should be the one providing clocking (ie. internal clock) out to all your T1 remote sites.

It sounds like you think the timing for the T3 and T1s are intertwined and in lockstep, but they aren't. The T3 loop clocking is seperate than the clocking each T1 circuit has.

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Doug McIntyre

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