Dear Jaap and Jeff,
Thank you for your replies. Unchecking the "Call subdissector for
retransmitted 802.11 frames" option does remove those retransmissions
marked previously. This helps a bit to look at which RTP packets are
lost (or not being captured in the air) clearly, but the statistics
calculation (i.e. RTP packet loss rate) is surely problematic.
Cheers,
Ji
-----Original Message-----
From: wireshark-users-bounces@xxxxxxxxxxxxx
[mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Jeff Morriss
Sent: 08 April 2008 13:53
To: Community support list for Wireshark
Subject: Re: [Wireshark-users] RTP packet lost statistics
Oh, I assumed that it was tracking the frames (based on a sequence
number or something) and only marking those that it saw more than once
as retransmissions. Just showing off my (complete) ignorance of 802.11
I guess ;-)
Jaap Keuter wrote:
> Hi Jeff,
>
> That depends if you want to assume that you've seen the originals of
the
> retransmitted frames or not. If you didn't you'll need them. If you
did, like
> in this case, you don't. Maybe there should be some sort of frame
tracking in
> there to match the operation of the endpoint toward it's protocol
stack.
>
> Thanx,
> Jaap
>
> Jeff Morriss wrote:
>> Ji Zhang wrote:
>>> Dear all,
>>>
>>> I'm currently using Wireshark v1.0.0 to analyse a Voice-over-802.11
>>> session trace captured by the Airopeek Wifi sniffer. I extracted the
RTP
>>> session and tried to use the Wireshark RTP statistics tool to
examine
>>> the RTP packet loss rate. However, Wireshark did not give the actual
RTP
>>> packet loss statistics, instead, what it gave was the statistics of
the
>>> number of RTP packet retransmissions and regarded these
retransmissions
>>> as packet losses. Obviously RTP packet retransmissions only could
happen
>>> at the 802.11 layer, so this would rather be more like 802.11 packet
>>> loss statistics.
>>>
>>> Could anybody let me know if this is the expected behaviour? If not,
is
>>> there any patch/upgrade that fixes the issue? If yes unfortunately,
is
>>> there any way I may get the packet loss statistics at the actual RTP
>>> layer using Wireshark? Much appreciated!
>> There is a preference for the 802.11 dissector
>> (Edit->Preferences->Protocols->IEEE 802.11): "Call subdissector for
>> retransmitted 802.11 frames". You might want to try turning that off
>> (the default appears to be on--should it be that way?).
>
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