02-07-2023 08:52 AM
Hi.
Please see attached pcap.
I'm in a classic argument as to the root cause of a failing transmission. May you please confirm (or not) that the below successful OSI layer 3 communication is evidence that this communication failure is NOT network related?
Thank you.
Solved! Go to Solution.
02-08-2023 04:37 PM
As TCP retransmissions are due to sender's TCP not getting ACKs from receiver's TCP, I would say it is a network problem, as TCP at L4, doesn't care what the app above it is.
Why is MSS 1380 in one direction and 1460 in the other direction?
02-07-2023 11:36 PM
Hello,
what is the context of your question, what problems are you experiencing, and what does your topology look like ? TCP retransmissions ' occur when the sender retransmits a packet after the expiration of the acknowledgement'. The cause of this can be a lot of things, so in order to determine the root cause, we need to know what you are actually running into.
02-08-2023 05:36 AM
The reporter reports "lack of communication between devices." Since the 3-way handshake is complete, that means to me that the network is not the cause of the retransmissions-- it must be the server in some way. Do you agree?
My best guess is that SFTP protocol is expected by the server, but not configured on the client.
02-08-2023 10:30 AM
Hello,
SFTP uses port 22. Is there any indication in the Wireshark capture of traffic being sent using that port ?
02-08-2023 05:20 PM
application chooses port 2222 for its sftp traffic.
02-08-2023 04:37 PM
As TCP retransmissions are due to sender's TCP not getting ACKs from receiver's TCP, I would say it is a network problem, as TCP at L4, doesn't care what the app above it is.
Why is MSS 1380 in one direction and 1460 in the other direction?
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