The blue and green flows requires a step by step presentation: Time 1: Both the blue and green flows send theirs first flits, 'i' and 'a'. Time 2: The flit 'i' can go on into the next buffer. But a buffer is dedicated to a packet from its first to its last flit, and so, the 'a' flit can not be forwarded. This is the start of a back-pressure effect. The 'j' flit can replace the 'i' flit. The 'b' flit can be sent. Time 3: The green packet goes on. The blue 'c' flit can not be forwarded (the buffer is occupied with the 'b' and 'a' flits): this back-pressure effect reaches the packet source. Time 4: As in time 3 Time 5: The green packet no longer uses the left-down buffer. The blue packet is unblocked and can be forwarded (assuming that the 'unblocked' information can be forwarded in null time) Time 6-10: The blue packet goes through the network.
The blue and green flows requires a step by step presentation: Time 1 Both the: blue and green flows send theirs first flits, 'i' and 'a'. Time 2: The flit 'i' can go on into the next buffer. But a buffer is dedicated to a packet from its first to its last flit, and so, the 'a' flit can not be forwarded. This is the start of a back-pressure effect. The 'j' flit can replace the 'i' flit. The 'b' flit can be sent. Time 3: The green packet goes on. The blue 'c' flit can not be forwarded (the buffer is occupied with the 'b' and 'a' flits): this back-pressure effect reaches the packet source. Time 4: As in time 3 Time 5: The green packet no longer uses the left-down buffer. The blue packet is unblocked and can be forwarded (assuming that the 'unblocked' information can be forwarded in null time) Time 6-10: The blue packet goes through the network.