Just had a 7-unit stack of 3750s go very wierd without warning after being up for nearly 3 years.
Although all the stacking cables were in and tight and there had been no config changes for 3 months, two units opted out of the stack without warning and the logs were filled with
%IPC-5-INVALID: Message port index=0x4 and 0x3
Needless to say the rest of the infrastructure in the building was unimpressed.
Power-cycling the whole stack brought it back and now it's running again as if nothing ever happened.
The stack is running on C3750-I9-M Version 12.2(20)SE4.
Has anyone seen this sort of thing before or can shed any light on what might have happened?