This is our old Q&A Site. Please post any new questions and answers at

I am using iperf to send a traffic for 60 seconds (i.e. i have an iperf client and iperf server). When I capture the traffic using both Wireshark and tcpdump, almost all of the packets have the same acknowledgement number but different sequence numbers. This is worrying me and is this healthy? Is it OK to have thousands of packets to have the same ack number?

asked 21 Apr '17, 14:09

armodes's gravatar image

accept rate: 0%

There are two Sequence numbers and two ACK numbers - one for each node in the conversation. So if you look at the sequence of the first node going up (which it does during sending data), you should see the ACK numbers of the other node doing the same (acknowledging the sent data).

The node not sending anything will not increase it's sequence number, and so also the ACK number will not increase of the other node. So, in short, what you see is not unusual at all.

permanent link

answered 21 Apr '17, 15:27

Jasper's gravatar image

Jasper ♦♦
accept rate: 18%

Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text]( "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 21 Apr '17, 14:09

question was seen: 2,763 times

last updated: 21 Apr '17, 15:27

p​o​w​e​r​e​d by O​S​Q​A