SONET and DS-1

Question

Recently we just switch from CES over an ATM backbone to SONET (454s and 327s). We have a requirement for point-to-point T1 circuits. The circuits worked fine over CES and all we did was move the circuits to the SONET. The tail end of the circuit remained the same. My question is more on the timing of the actual T-1 circuit itself. Is timing for the individual DS-1 circuits provided by the SONET timing source or by the individual circuit itself? In other words do I set up the CSU devices connected to the SONET box to receive timing from the NI or do I need to set up the CSUs as if they are connected back-to-back (One as a master and one as a slave).
These circuits worked fine from the ATM/CES and the SONET boxes are in the same location as the ATM boxes. Timing issues for ATM/CES are more specific than the SONET and timing was clearly addressed. Provsioning of the circuit through SONET is correct (Line coding, framing etc.) No documentation that I have found addresses this question (at least not plainly) on the timing for individual DS-1 circuits. Cisco Support has said that each individual circuit must provide it's own timing. This is not working and even though there are no SONET alarms the WAN link is still lost intgermittently

Answer 1

SONET does NOT provide timing to the circuits it carries. In the case of your point-to-point circuit, set up the timing on your CSU's. On one end set it up for "master" or "internal" (or whatever sounds close, seems like they're all different), then set the other end up for "slave" or "line". Most CSU's will provide an internal clock; while it's not the best quality, as long as both DTE's are referencing the same source you shouldn't have a problem.