This is port on this management service interface, identifying which specific physical management port, for example on a fabric interconnect with two mgmt ports, this interface record refers to. On hardware with redundant management ports, this number is how an admin confirms which physical port a given interface's addressing and status actually correspond to, when only one port is cabled. A value of 0 might refer to the primary mgmt0 port, while a value of 1 would refer to a secondary mgmt1 port on the same fabric interconnect.