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Previous segment not captured and tcp out-of-order

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Hi!
I have warnings "TCP Previous segment no captured" and "TCP Out-Of-Order".

https://ibb.co/3BTxV06

https://ibb.co/1sfMRDQ

I guess it's because the second part of the segment comes first. For example, first comes segment Seq=12586 Ack=3056 Len:187. And then comes segment Seq=11138 Ack=3056 Len:1448. But Seq=11138 must be first.

And i have a lot of those segments. What could be the reason? Help me, please. Is this a network problem?

Thank you!

itbn's avatar
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itbn
asked 2021-02-11 12:17:43 +0000, updated 2021-02-11 12:30:11 +0000
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You're right with your guess. There are different reasons why the packets didn't arrived in order. The most likely reason is that your capture device or driver was not able to keep the original order of the packets because of the total amount of received packets. The size of the packets might be a reason too, because according to your screenshot only full-size packets with a size of 1514 bytes are having this problem.

Another reason could be the router between the two communication partners. Larger packets may be "overtaken" by the smaller ones due to performance reason.

This is not a problem for the network, the clients or the application. The time difference between the messed up packets is very small or not existing, and TCP is responsible to reassemlbe the stream at the destination.

JasMan's avatar
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JasMan
answered 2021-02-11 20:54:52 +0000
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Thank you!

itbn's avatar itbn (2021-02-15 07:18:46 +0000) edit
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