The output of the "admin show controllers switch <0-1> statistics location <node>" on a CRS-PRP displays port 6 is connected to Tunn MCU.
Example:
RP/0/RP0/CPU0:CRS-3#admin show controllers switch 1 statistics location 0/RP0/CPU0
Fri Aug 23 13:19:04.938 MEST
Port Tx Frames Tx Errors Rx Frames Rx Errors Connects
-----------------------------------------------------------------------------------------------------
0 : 0 0 0 0 RP0
1 : 923074857 0 1031857878 0 RP1
2 : 422682332 0 105850585 0 F0
3 : 422736850 0 105905135 0 F1
4 : 422686740 0 105854663 0 F2
5 : 422994927 0 106162993 0 F3
6 : 334602025 0 245904 0 Tunn MCU
7 : 0 0 0 0 Unused
[SNIP]
MCU is a chip , which provides the console tunneling feature. It has a connection to the BCM switch and two console like 9.6K ports to the CPU. MCU captures console characters from the CPU complex and convert them into Ethernet frames which will be sent out on the control network.
