This object sets this SRP interface's clock source to internal, used over dark fiber or WDM between two routers and the default, or line, used when connecting a router to a SONET or SDH ADM. Getting this wrong on a ring segment connected to SONET or SDH equipment causes clock-source conflicts leading to bit errors or link instability on that specific segment, since two internally clocked ends, or two line-clocked ends, fighting for master timing is a classic SONET-style timing misconfiguration. A segment connected to a SONET ADM that is mistakenly left at the internal(1) default, instead of being set to line(2), would likely show bit errors or intermittent link flaps caused by clock-source mismatch with the ADM's own timing.