First time here? Check out the FAQ!
THIS IS A TEST INSTANCE. Feel free to ask and answer questions, but take care to avoid triggering too many notifications.
Ask Your Question
0

TCP Dup ACK and TCP Previous segment

  • retag add tags

Hello, I have a problem with the database on the server (19.168.1.100). There are cases where the same records are duplicated to the database.

No.  Time      Source          Destination    Protocol Length Info
19   0.160086  195.69.209.165  192.168.1.100  TCP      60     [TCP Dup ACK 18#1] 443 → 56386 [ACK] Seq=156 Ack=551 Win=4930 Len=0

and 
No.  Time       Source          Destination    Protocol Length Info
812  12.160016  195.69.209.165  192.168.1.100  TLSv1    91     [TCP Previous segment not captured] , Application Data

What could be the reason for these errors? Switcher or network card in the server?

marcinsgdz's avatar
1
marcinsgdz
asked 2019-02-06 17:42:43 +0000
grahamb's avatar
23.8k
grahamb
updated 2019-02-06 17:55:53 +0000
edit flag offensive 0 remove flag close merge delete

Comments

add a comment see more comments

1 Answer

0

It seems highly unlikely that the TCP symptoms you pasted have anything to do with duplicate records in the database. A duplicate ACK is just a message telling the other side that a packet hasn't been received when it should have, and "Previous segment not captured" means that a packet is missing. TCP connections transport data reliably (or fail completely, after retrying without success), but it doesn't duplicate anything when it comes to the actual application payload.

Having programmed database applications myself I am reasonably sure that the problem is somewhere in the database/application logic, not the network That would mean that switches and network cards are not to blame for this.

Jasper's avatar
24.1k
Jasper
answered 2019-02-07 12:25:36 +0000, updated 2019-02-07 12:26:15 +0000
edit flag offensive 0 remove flag delete link
more

Comments

add a comment see more comments

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account. This space is reserved only for answers. If you would like to engage in a discussion, please instead post a comment under the question or an answer that you would like to discuss.

Add Answer