Solved: For future reference, figured out that it was in fact an XG port.  Unit 3, the CX4 module XG3 error due to the Unit 2 CX4 module XG4 was down.
I have three stacked 6248s, running version 3.3.18.1. The three are connected by stacking modules as well as interconnected by 10 gig CX4 modules. Something has changed and unit #2, interface X4 is now marked "Down" while all of the other interfaces are showing "Up". I've rebooted the stack and the connection remains down, possibly a bad CX4 module. With the module wires criss-crossed as expected will this ensure data continues to flow as expected? The main reason for this posting is that I am also seeing non-stop postings in the "Buffer Log" of: I have NO idea what 3/0/51 is telling me.  It sure looks like unit 3 and port 51 but on a 6248 port 51 isn't exactly possible, unless it has to do with the CX4.  Does anybody know what this error is pointing at? Any advise is greatly appreciated. Unit / Interface / Mode / Link Status / Speed 1 xg1 Stack Up 121 xg2 Stack Up 121 xg3 Ethernet Up 101 xg4 Ethernet Up 102 xg1 Stack Up 122 xg2 Stack Up 122 xg3 Ethernet Up 102 xg4 Ethernet Down Unknown3 xg1 Stack Up 123 xg2 Stack Up 123 xg3 Ethernet Up 103 xg4 Ethernet Up 10
Stacked 6248s / Unknown Port Error