I'm putting a lab together messing around with different technology and got these two different Verilink Access 2000 boxes. These are T1 boxes and I have them configured using ESF and B8ZS coding. However both boxes are set as DSU's in the configuration which means they are both providing there own clocking signal, correct? Is this possible because everything is working. I just thought one had to be set to a CSU and the other as a DSU? I'm a little new to this technology. Any would be greatly appreciated a explantion of the setup. These are setup as point to points between two routers.
Thanks  

Both Verilinks are set at "DIU clock net" does this mean that it is getting the clocking information from the network? From the manual it states the "DUI-The CSU uses a clock provided by DTE connected to a dataport on a DUI 213x module. Trail circuit timing requires this option."

Any help would be appreciated. I actually have the T1 verilinks running through a Adtran T3 box on one end both configured for ESF framing and on the other end running through a cisco router. Just not quite sure on how the clocking is working between the two.