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

Hello,

I have the attached photos for a capture for Wifi Frames in Wireshark.

alt text

When I was analyzing the frame format for different packets, I found that when I move from the MCS Information field to the A-MPDU status field, three bytes are being escaped by Wireshark. So I checked the Radio Tap header format, and I found nothing is mentioned about these three bytes. So could you please clarify why three bytes are ignored by the parser.

Additionally according to the A-MPDU Status field definition in the following Site, the structure should be aligned by 4 bytes. So the subfields should be multiple of 4 bytes i.e. The A-MPDU Status should be 16 Bytes long, correct?

Notes:

  1. The three Bytes have a value of zero.

  2. The original capture file can be found in the following link Capture File

asked 12 Jun '15, 11:37

Hany%20Assasa's gravatar image

Hany Assasa
21101114
accept rate: 0%


This is because the A-MPDU Status field requires a 4 bytes alignment, meaning that the structure must start at a multiple of 4 bytes. The 3 bytes set to 0 are padding between the end of the MCS field and the beginning of the A-MPDU Status field. You can read the "Alignment in Radiotap" paragraph on http://www.radiotap.org/ for more details.

permanent link

answered 12 Jun '15, 12:01

Pascal%20Quantin's gravatar image

Pascal Quantin
5.5k1060
accept rate: 30%

edited 12 Jun '15, 12:07

Your answer
toggle preview

Follow this question

By Email:

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

By RSS:

Answers

Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text](http://url.com/ "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:

×134
×19
×16

question asked: 12 Jun '15, 11:37

question was seen: 2,954 times

last updated: 12 Jun '15, 12:07

p​o​w​e​r​e​d by O​S​Q​A