General
The command clock source internal is applicable to data T1/E1 and is not used for T1/E1 voice. Both data and voice can run on the same NIM module.
Symptom
As per the below documentations, clock source internal should be only used for data under T1 E1 and not for voice,so ideally ds0 group configuration should not be allowed when the clock source internal is configured under E1 controller configuration. However we could find that if we are configuring clock source internal after ds0 configuration, gateway allows that configuration. This is not an expected behavior as per this documentation.
https://www.cisco.com/c/en/us/td/docs/routers/access/interfaces/NIM/software/configuration/guide/4gen-t1-e1-nim-guide.html
This causes the gateway to reload without E1 controller configurations.
Conditions
Clock source internal should be configured under E1 controller for the issue to reproduce.
Workaround
clock source internal should not be configured within E1 controller configuration. By default it takes clocking from clock source line primary.
Further Problem Description
Its a cosmetics issue.
