nimdrak's profile - activity

I try to understand the TCP behavior, especially re-transmission.

I did a small experiment and find the curious thing.

The only last packet is re-transmitted. Why do this happen?

I think if the last packet is time-out, then the other packets have to be time-out because All packets in the flow have same RTT and RTO.

At first, I think it is due to delayed ack. Therefore, I did a same experiment with setsockopt TCP_QUICKACK. But I saw the same phenomenon. ( But I am not sure yet, that the cause of this is not delayed ack. )

Could you give me a little help? Thank you for reading :)

For example,

[1] H1->H2 send a 1500 bytes packet

[2] H1->H2 send a 1500 bytes packet

[3] H1->H2 send a 1500 bytes packet

...

[n] H1->H2 send a 800 bytes packet [the last packet]

[n+1] H1->H2 re-send a 800 bytes packet [the last packet]

[n+2] H2->H1 send an ACK.

[the raw data from wireshark]

1735203 51.249349738    10.0.0.1    10.0.0.2    TCP 1514    35250 → 50021 
[ACK] Seq=16124342 Ack=1 Win=58 Len=1448 TSval=902298 TSecr=902296

1735204 51.249349999    10.0.0.1    10.0.0.2    TCP 1514    35250 → 50021 
[ACK] Seq=16125790 Ack=1 Win=58 Len=1448 TSval=902298 TSecr=902296

1735205 51.249350340    10.0.0.1    10.0.0.2    TCP 866 35250 → 50021 
[PSH, ACK] Seq=16127238 Ack=1 Win=58 Len=800 TSval=902298 TSecr=902296

1735207 51.258283589    10.0.0.1    10.0.0.2    TCP 866 
[TCP Retransmission] 35250 → 50021 [PSH, ACK] Seq=16127238 
Ack=1 Win=58 Len=800 TSval=902301 TSecr=902298

1735208 51.258288919    10.0.0.2    10.0.0.1    TCP 66  50021 → 35250 
[ACK] Seq=1 Ack=16128038 Win=32766 Len=0 TSval=902301 TSecr=902298

EDIT:

* Attached captured files *

https://www.dropbox.com/s/1mtgtv5xof6...

https://www.dropbox.com/s/1mtgtv5xof6...

Each files is the packet captured at each host.

If you don't mind, please check the files.

EDIT EDIT:

* Attached a captured file for understanding *

https://www.dropbox.com/s/fmgkpybhiod...

Thank you for reading!

Before studying your answer, I deeply appreciate you. Actually I thought whether I have to give up. But I will not thank

@Spooky Sure! I’m sorry. https://www.dropbox.com/s/5i1bgnv33eizue3/host1_data.pcapng?dl=0

Is it possible to re-transmit only the last packet at TCP flow? I try to understand the TCP behavior, especially re-tran

Is it possible to re-transmit only the last packet at TCP flow? I try to understand the TCP behavior, especially re-tran

Is it possible to re-transmit only the last packet at TCP flow? I try to understand the TCP behavior, especially re-tran

@Spooky I always appreciate your help. Actually the application is mininet-virtual network. it is consist of only two ho

@Spooky I always appreciated your help. Actually the application is mininet-virtual network. it is consist of only two h

@Christian_R https://www.dropbox.com/s/1mtgtv5xof6octn/host2_data.pcapng?dl=0 https://www.dropbox.com/s/1mtgtv5xof6octn/

@Christian_R I will! Thank you so much for your comment :)

Is it possible to re-transmit only the last packet at TCP flow? I try to understand the TCP behavior, especially re-tran

@SYN-bit Thank you so much! I don't know the concept "delayed ACK". After studying, I will do troubleshooting with it. I

Slow Response - host send a ACK packet slowly than usual I study the Behavior TCP and did a small experiment about TCP.

I found an answer. TSO option ON at NIC card make it difficult to analyze the packets. After turning off TSP option, I

@grahamb although I closed this question, I cannot open the original question due to the lack of points. Could you help

although I closed this question, I cannot open the original question due to the lack of points. Could you help me?

@grahamb I did! Thank you for your comment!

@grahamb I did! Thank you for your comment!

Weired TCP retransmission My question is why a TCP flow make a re-transmission when a network has enough link bandwidth.

Weired TCP retransmission My question is why a TCP flow make a re-transmission when a network has enough link bandwidth.

@Spooky I totally understand! :) I really appreciate you. Then could I conclude the two?, "(1) .1 host lost its packet w

@Jaap Thank you for your explanation! If you don’t mind, could you check my understanding? The host at port 50012 receiv

@Jaap I really appreciate your comment. But I couldn't understand your words, due to lack of my understanding about, may

The reason a TCP connection generate retransmission My question is why a TCP flow make a re-transmission when a network

The reason a TCP connection generate retransmission My question is why a TCP flow make a re-transmission when a network

The reason a TCP connection generate retransmission My question is why a TCP flow make a re-transmission when a network