Described are embodiments of methods, apparatuses, and systems for multi-protocol tunneling across a multi-protocol I/O interconnect of computer apparatus. A method for managing flow across the multi-protocol I/O interconnect may include providing, by a first port of a switching fabric of a multi-protocol interconnect to a second port of the switching fabric, a first credit grant packet and a second credit grant packet as indications of unoccupied space of a buffer associated with a path between the first port and a second port, and simultaneously routing a first data packet of a first protocol and a second data packet of a second protocol, different from the first protocol, on the path from the second port to the first port based at least in part on receipt by the second port of the first and second credit grant packets. Other embodiments may be described and claimed.