Middlebox tracing in software defined networks

A computer usable program product comprising a computer readable storage device including computer usable code, the computer usable code comprising:

• computer usable code for inserting, at a switch in a software defined network (SDN), a tracing packet from an SDN controller, the tracing packet including a default value in a tag field;
• computer usable code for receiving, at the SDN controller, from the switch, a returned packet and a port identifier, the returned packet including a modified content in a location of the tracing packet that is different from the tag field, the port identifier corresponding to a port of the switch on which the switch received the returned packet from an middlebox;
• and
• computer usable code for identifying a function and a location of the middlebox by analyzing a modification applied to the modified content by the middlebox, the location comprising the port identifier and an identifier of the switch.

A data processing system comprising:

• a storage device, wherein the storage device stores computer usable program code;
• and
• a processor, wherein the processor executes the computer usable program code, and wherein the computer usable program code comprises:
• computer usable code for inserting, at a switch in a software defined network (SDN), a tracing packet from an SDN controller, the tracing packet including a default value in a tag field;
• computer usable code for receiving, at the SDN controller, from the switch, a returned packet and a port identifier, the returned packet including a modified content in a location of the tracing packet that is different from the tag field, the port identifier corresponding to a port of the switch on which the switch received the returned packet from an middlebox;
• and
• computer usable code for identifying a function and a location of the middlebox by analyzing a modification applied to the modified content by the middlebox, the location comprising the port identifier and an identifier of the switch.