Bug 875 – "frame includes FCS" flag should be set in Radiotap frame header

Bug 875 - "frame includes FCS" flag should be set in Radiotap frame header


Summary:	"frame includes FCS" flag should be set in Radiotap frame header

Status:	RESOLVED FIXED

Product:	ns-3
Classification:	Unclassified
Component:	helpers
Version:	ns-3-dev
Hardware:	All All

Importance:	P5 normal
Assigned To:	Dean Armstrong

URL:	http://codereview.appspot.com/904042
Keywords:	bug

Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2010-04-13 14:25 EDT by Dean Armstrong
Modified:	2010-05-14 16:27 EDT (History)
CC List:	2 users (show)

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Description Dean Armstrong 2010-04-13 14:25:46 EDT

The Wi-Fi PCAP tracing with Radiotap data link format captures the entire MPDU including FCS, so the "frame includes FCS" flag in the Radiotap header for each frame should be set so that tools like Wireshark won't try to decode this field as MPDU payload.

The current undesired behaviour can be seen by taking a PCAP/Radiotap trace including (for example) a Beacon frame, and then loading this into Wireshark. Looking at the "Tagged Parameters" section you'll see that Wireshark has decoded the last four octets (i.e., the FCS) as two zero length SSID information elements.

Comment 1 Dean Armstrong 2010-04-13 14:28:13 EDT

A proposed patch for this is available at:

http://codereview.appspot.com/904042

Please comment.

Comment 2 Dean Armstrong 2010-04-13 14:53:14 EDT

The wifi-wired-bridging test reference traces will need updating when this bug is fixed (this appears to be the only test that uses Radiotap tracing). The updated traces are also available under the 'afore-mentioned codereview issue.

Comment 3 Dean Armstrong 2010-05-10 09:02:32 EDT

I would like to deal with this bug in the near future. Is the bug, and code I previously proposed as Issue 904042 on codereview contentious, or can I go ahead and fix it?

Comment 4 Nicola Baldo 2010-05-14 13:07:00 EDT


(In reply to comment #3)
> I would like to deal with this bug in the near future. Is the bug, and code I
> previously proposed as Issue 904042 on codereview contentious, or can I go
> ahead and fix it?

Hi Dean, sorry for the late reply. The bug is confirmed and the patch is ok, so please go ahead and commit. Thanks for the good work!

Comment 5 Dean Armstrong 2010-05-14 16:27:54 EDT

Fixed by:

changeset 6299:56ac87d0f2f9 on ns-3-dev, and
changeset 114:0a54dfc12e7f on ns-3-dev-ref-traces