I'm hoping that somebody can answer this question for me.
I have two Cisco 2600 (2610 and 2611) connected back to back with WIC-1DSU-T1 cards and a suitable T1 cable that I've made. For both interfaces I've configured a IP address and no shutdown'ed the interface, and after a few seconds everthing is working and I can ping the other interface.
However, everything I've read suggests that I have to specify a clock source (service-module t1 clock source internal) on one interface for the line to work. The other interface needs to be slaved using the service-module t1 clock source line.
I have not but the link comes up and this suprises me. Can anybody explain why please?