Symptom
ASR9K keeps sending out Bytes though the Aux port even though there is no Active Session
Conditions
Only seen when AAA is configured on the auxiliary and there is a devices connected to it.
Workaround
Remove AAA from the auxiliary port.
By default we will protect this port via local user authentication.
Further Problem Description
We can use the following output to see that there is no active session on the Aux port and that we are constantly and indefinitely sending Bytes out:
RP/0/RSP1/CPU0:XR1#show line aux location 0/rsp1/cpu0
Tty Speed Overruns Acc I/O
aux0/RSP1/CPU0 9600 0/0 -/-
RP/0/RSP1/CPU0:XR1#show line statistics aux end-to-end | in hw buffer
Bytes hw buffer recieved: 291 <--- Packets/Bytes coming to the ASR9K (do not increase)
Bytes hw buffer recieved from DP: 6256 <--- Packets/Bytes leaving the ASR9K (keeps increasing)
Those Bytes are actually the AAA authentication prompt that is being sent out and displayed on the other end:
User Access Verification
Username:
This behavior by itself is harmless though if AAA is configured to use TACACS for authentication then we will be sending out a request to the TACACS for each login prompt we display. It may become a problem is many ASR9K AUX ports are cabled then we would be flooding the TACACS with unnecessary login requests.
