I really don't have a clue on this so i hope someone could help me understand why.
i have a 4510 sup7e connected with single mode fiber to a 3850 using 10 gig with 10GBase-LR optics.
The issue I had was the port would go offline into err-disabled because of (pasted from log)
*Sep 15 14:25:01.276 CST: %UDLD-4-UDLD_PORT_DISABLED: UDLD disabled interface Te6/2, unidirectional link detected
*Sep 15 14:25:01.276 CST: %PM-4-ERR_DISABLE: udld error detected on Te6/2, putting Te6/2 in err-disable state
One side was set to trunk and the other side was not. Why would this cause a UDLD issue. When the other port was configured as a trunk it came right up.
Anyone? Why would trunking config affect UDLD?