Forward Progress Assurance and Quality of Service Enhancement in a Packet Transferring System

1. A method implemented in an initiating node, the method comprising: detecting that at least one Quality of Service (QoS) requirement is met, wherein the QoS requirement indicates that an expected packet from a source node in a multi-hop network comprising multiple nodes is outstanding, wherein the expected packet is designated as a very important packet (VIP); sending a first message via a communication channel to an adjacent node in response to the detecting that at least one QoS requirement is met, wherein the communication channel is divided into a plurality of virtual channels, wherein at least one of the plurality of virtual channels is a reserved virtual channel (VIP channel) that is activated when a VIP protocol is activated, wherein the VIP channel is a dedicated channel that can be accessed only by the initiating node and the adjacent node, and wherein the VIP protocol is activated in response to the first message to locate the expected packet; and receiving the VIP via the VIP channel.

2. The method of claim 1 , wherein the QoS requirements comprise receiving a barrier transaction the VIP will satisfy, sending the barrier transaction, receiving a packet of a sequential operation out of order, receiving more than a threshold number of packets of a VIP's packet type, and exceeding a time limit for receiving the VIP.

3. The method of claim 2 , wherein the first message comprises information identifying the VIP, wherein the information identifying the VIP comprises indications of the source node, a destination node, and the packet type, and wherein the adjacent node is located within a plurality of possible routing paths between the source node and the destination node.

4. The method of claim 2 , further comprising sending a second message to the adjacent node via a physical channel upon receipt of the VIP, wherein the VIP protocol is deactivated in response to the second message.

5. The method of claim 3 , wherein only the destination node may terminate the VIP protocol.

6. The method of claim 3 , further comprising rejecting any packets that are non-VIPs while the VIP protocol is active.

7. The method of claim 6 , further comprising resending any non-VIPs rejected while the VIP protocol is active.

8. The method of claim 3 , wherein the adjacent node promptly forwards the VIP via the VIP channel when the VIP is present in the adjacent node, and wherein the adjacent node refrains from sending non-VIPs while the VIP protocol is active.

9. The method of claim 3 , wherein the adjacent node sends a copy of the first message to an adjoining node within a possible routing path between the adjacent node and the source node if the VIP is not present in the adjacent node, wherein the copy of the first message activates at least one downstream VIP channel between the adjacent node and the adjoining node, and wherein the adjacent node promptly forwards the VIP via the VIP channel upon receiving the VIP from the adjoining node via the downstream VIP channel.

10. The method of claim 1 , wherein the VIP channel comprises bandwidth for one packet.

11. An apparatus comprising: a buffer; a processor coupled to the buffer and configured to monitor the buffer and detect when at least one Quality of Service (QoS) requirement is met, wherein the QoS requirement indicates a very important packet (VIP) expected from a source node in a multi-hop network comprising multiple nodes is outstanding; a transmitter coupled to the processor and configured to send a VIP protocol initiation message via a communication channel to an adjacent node in response to the detection, wherein the communication channel is divided into a plurality of virtual channels, wherein at least one of the plurality of virtual channels is a reserved virtual channel (VIP channel) that is activated when a VIP protocol is activated, wherein the VIP protocol is activated in response to the VIP protocol initiation message to locate the VIP, and wherein the VIP channel is a dedicated channel that can be accessed only by the apparatus and the adjacent node; and a receiver coupled to the processor and configured to receive the VIP via the VIP channel.

12. The apparatus of claim 11 , wherein the QoS requirements comprise receiving a barrier transaction the VIP will satisfy, sending the barrier transaction, receiving a packet of a sequential operation out of order, receiving more than a threshold number of packets of a VIP's packet type, and exceeding a time limit for receiving the VIP.

13. The apparatus of claim 11 wherein the processor is further configured to cause the transmitter to send a VIP termination message after the receiver receives the VIP, and wherein the VIP termination message terminates the VIP protocol.