Dec 24, 2018 · The reason I asked if you have any other problems is because a lot of DUP ACK's could be caused by a bad (physical) link somewhere in the chain. A bad wire, or a cable that's too long, crosstalk, But then I would expect you to see other problems on the site too, not just the site-to-site VPN.

Jul 20, 2008 · A DUP ACK will be sent for every out-of-order segment received. So if one or more segments are dropped, every one that's received after that until the expected segments are received will generate a DUP ACK. How many DUP ACKs depend on the bytes in flight. Aug 22, 2008 · TCP [TCP Dup ACK 245#1] 3015 > 3838 [ACK] Seq=15 Ack=2521 Win=34020 Len=0 SLE=3781 SRE=4679 But anyway, the client FINs after receiving 4679 bytes from the server. It had only sent in the request of 14 bytes to the server It’s all part of TCP congestion control. Based on the wording of the question, you are describing the TCP Tahoe method. A timeout clearly indicates serious path congestion, so you want to SLOW THE HELL DOWN and stop sending so much data. In the diagram, there is only 1 dup ACK caused by Pkt2. The diagram below depicts how 3 duplicate ACKs lead to a fast retransmit: Assumptions: 1. Only one packet in a window is dropped. In this diagram, it is Pkt5. 2. TCP at the sending side implements fast retransmit algorithm. 3. Aug 28, 2016 · 38 15:40:16.819790 client server TCP 66 [TCP Dup ACK 29#3] 16578 > 443 [ACK] Seq=1285985661 Ack=2844946993 Win=31856 Len=0 TSval=2523566064 39 15:40:16.819792 client server TCP 66 [TCP Dup ACK 29#4] 16578 > 443 [ACK] Seq=1285985661 Ack=2844946993 Win=31856 Len=0 TSval=2523566064 40 15:40:16.820063 server client TLSv1 1514 Ignored Unknown Record

Feb 15, 2017 · TCP provides reliable, ordered, and error-free transmission. To do so TCP has features such as Handshake, Reset, Fin, Ack, Push packets, and other types of flags to keep the connection alive and to not lose any information. TCP is used under a number of application protocols, such as HTTP, so it is important to know how to diagnostic TCP issues.

ただ実際にログを確認するとretransmissionでDup ACKが消えていることがわかったのでこの設定はいらないようだ。 ではこのエラーがWindows 7特有のTCPレイヤ上の問題と考えたらどうだろうか。Windows 7独自のパラメータがあるかもしれない。

80 → 62765 [ACK] Seq=16061 Ack=1192 Win=17520 Len=1460 [TCP segment of a reassembled PDU] 34: 7.382573: [TCP Dup ACK 192#1] 62772 → 80 [ACK

Note that this ACK is duplicate of an ACK which was previously sent. The reason to do this is to update the sender with regards to the dropped/missing TCP segments. Once, 2 DUP ACKS(Dupilcate Acknowledgements), TCP performs a retransmission of that segment without waiting for the expiry of the retransmission timer. This is known as Fast Retransmit. Dup ACK を3回受信する前、かつ 3ms 以内にその ACK で要求しているパケットを受信した (再送されたのか遅れて来たのかは不明) ただし、インタフェースの高速化が進んだ現状において、TCP の再送はマイクロ秒オーダーでも発生している現実があり、再送 TCP Retransmission is a process of retransmitting a TCP segment. TCP Retransmission occurs when time out timer expires before receiving the acknowledgement or 3 duplicate acknowledgements are received from the receiver for the same segment. RDT protocol was the basis for the implementation of TCP protocol.RDT protocol use to retransmit the packet only when timer expires .TCP now uses duplicate acks as well as timeout to retransmit a packet if lost. So - if you're seeing a few random duplicate ACK's but no (or few) actual retransmissions then it's likely packets arriving out of order. If you're seeing a lot more duplicate ACK's followed by actual retransmission then some amount of packet loss is taking place. Both situations are, unfortunately, entirely possible on the global Internet. 今回は、TCP Retransmit と DupACK と Fast Retransmit の紹介を行います。いずれも、パケットロスといったネットワークの性能が出ない時に出現するキーワードです。 【TCP Retransmit】Retransmit とは”再送”を意味する英単語です。TCPでは、TCPデータの送信者が、受信者からACKを受け取れなかった場合、TCP