Go to LD 137 and stat elnk.
Also, if the PBX is restarting it's ethernet driver there is another issue at hand. Likely it's not liking what it's seeing at Layer 1. What is it physically plugged into? If a switch, you may need to hard code that switch port to 10 HALF (if on an 11c)
Follow the steps in the NTP to set the Active ELNK in LD 117 if there is no layer one issue.