Symptom
When using QSFP-4X10G-LR-S on 9500-24Q interfaces status are not interpreted correctly.
Topology:
MASTER CLIENT
9500-24Q [Fo2/0/13 (Te2/0/49-52)] [Fo1/0/1-4] 9500-12Q (seen as Forty but SFPs are 10G)
Seen from the client perspective (4x10G):
When we shutdown the Fo1/0/1 on the client side, Te2/0/49 and Te2/0/51 ports go down.
When we shutdown the Fo1/0/3 on the client side, Te2/0/49 and Te2/0/51 ports go down.
When we shutdown the Fo1/0/2 on the client side, Te2/0/50 port go down (expected)
When we shutdown the Fo1/0/4 on the client side, Te2/0/52 port go down (expected)
In faulty scenario interfaces status on the client side is still up/up despite of lack of connectivity. On the master side it's down/down.
Seen from the master (40G physical port, and 4 logical 10G):
When we shutdown the Te2/0/49 on the master side, Fo1/0/3 port go down. Lack of connectivity on Fo1/0/1 despite of up/up.
When we shutdown the Te2/0/51 on the master side, Fo1/0/1 port go down. Lack of connectivity on Fo1/0/3 despite of up/up.
When we shutdown the Te2/0/50 on the master side, Fo1/0/2 port go down (expected)
When we shutdown the Te2/0/52 on the master side, Fo1/0/4 port go down (expected)
Conditions
1. 9500-24Q
2. IOS-XE 16.12.1
3. Using QSFP-4X10G-LR-S breakout cable.
Workaround
The problem happens to C9500-24Q and port 13-17.
Work-around is to use other 19 40G ports for breakout application
