24 Personally I don't even feel that there is a need for ACK. It's faster if we just send NACK (n) for the lost packets instead of sending an ACK for each received packet. So when/which situations would one use ACK over NACK and viceversa?
Why do you think there should be a RST segment before RST/ACK? Maybe you could provide an example of such a packet trace?
Why do I see a RST, ACK packet instead of a RST packet?
The first part finds SYN packets, and the second part find packets for which the return trip time analysis hasn't happened - which implies that Wireshark hasn't seen a corresponding ACK. Obviously, this will also find SYN packets which were ACKed after you stopped the capture, so use a long capture. Edit This filter was too narrow, it should be:
The ACK flag indicates that the Acknowledgment Number field is significant, ie. containing a meaningful value. When a socket connection has already been established that is nearly always the case, but it isn't while a connection is being established. Acknowledgment Number: 32 bits If the ACK control bit is set this field contains the value of the next sequence number the sender of the segment ...
Why need Ack flag if we already have ack number in TCP
In Wireshark, I see TCP duplicate ACK packets sent from the receiver to the sender. What does it mean? Does it imply packet loss? Thank you
Copy-pasting from my lecturer's slides: Receiver indicates the window size is 3000 Transfer goes ahead Acknowledge every 3000 bytes Receiver increases window size to 4000 4000 bytes ...