Data unit transmission method and device

A method of controlling a receiving network entity for receiving a data unit arranged in accordance with a predetermined communication protocol, said network operating according to said predetermined communication protocol, said data unit being sent from a sending network entity to said receiving network entity over one or more forwarding network entities, said data unit having a first data field arranged to contain network entity identification information, said first data field being different from a forwarding data field designated by said communication protocol to contain information to be used by forwarding network entities for forwarding said data unit to the receiving network entity, said first data field being defined such that a given network entity that reads the first data field can at least make a decision on the basis thereof whether said given network entity is identified or not, and furthermore being defined such that a given network entity that reads the network entity identification information can make a decision on the basis thereof whether no network entity at all is identified by said first data field, said method comprising:

• sending a feedback message to said sending network entity after having received said data unit, said feedback message containing information related to the receipt of said data unit, and
• including in said feedback message information that indicates to said sending network entity that no network entity was identified in said first data field of said data unit if
• said network entity identification information in said first data field identifies no network entity at all, or
• it is determined that the data unit has not passed the network entity identified by the network entity identification information in said first data field,
• and otherwise including in said feedback message information that indicates to said sending network entity the identity of the network entity identified in said first data field.

A network entity for receiving a data unit arranged in accordance with a predetermined communication protocol, said data unit being sent from a sending network entity to said receiving network entity over one or more forwarding network entities, said data unit having a first data field arranged to contain network entity identification information, said first data field being different from a forwarding data field designated by said communication protocol to contain information to be used by forwarding network entities for forwarding said data unit to the receiving network entity, said first data field being defined such that a given network entity that reads the first data field can at least make a decision on the basis thereof whether said given network entity is identified or not, and furthermore being defined such that a given network entity that reads the network entity identification information can make a decision on the basis thereof whether no network entity at all is identified by said first data field, said receiving network entity comprising:

• a data unit receiver for receiving said data unit,
• a message generator for generating a feedback message to be sent to said sending network entity, said feedback message containing information related to the receipt of said data unit, said message generator comprising an element for including in said feedback message information that indicates to said sending network entity that no network entity was identified in said first data field of said data unit if
• said network entity identification information in said first data field identifies no network entity at all, or
• it is determined that the data unit has not passed the network entity identified by the network entity identification information in said first data field,
• and otherwise including in said feedback message information that indicates to said sending network entity the identity of the network entity identified in said first data field and
• a message output for outputting said feedback message.