Wireshark-users: Re: [Wireshark-users] Ethernet flow control
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From: Jaap Keuter <jaap.keuter@xxxxxxxxx>
Date: Fri, 05 Dec 2008 00:07:25 +0100
Hi,

I haven't worked with them myself. Wikipedia is your friend here:
http://en.wikipedia.org/wiki/Pause_frame

Thanx,
Jaap


Jake Peavy wrote:

Thanks Jaap,
I should probably start off by saying that I'm not sure I understand flow control completely; I'm a little out of my depth.
I've also tried capturing off the full duplex 10/100 switch, but don't see them there either.
Should I just be able to look for eth.type == 0x8808 in order to see flow control information or do I need to look inside the Frame/Ethernet headers?
I did look at the sample capture: http://wiki.wireshark.org/SampleCaptures?action=AttachFile&do=get&target=Ethernet_Pause_Frame.cap <http://wiki.wireshark.org/SampleCaptures?action=AttachFile&do=get&target=Ethernet_Pause_Frame.cap> but I'm not sure if that's what to expect. If it is, and if they're there, I'm definitely not seeing them. 

Thanks again,
-jp
On 12/4/08, *Jaap Keuter* <jaap.keuter@xxxxxxxxx <mailto:jaap.keuter@xxxxxxxxx>> wrote: 

    Hi Jake,

    Sticking in a hub will make it half duplex, so full duplex rate
    control is out
    of the question. Better get a passive tap.

    Thanx,
    Jaap


    Jake Peavy wrote:
     > Hello all,
     >
     > I believe we're running into an issue caused by one device
    sending PAUSE
     > frames onto the wire and impairing the bandwidth delivered by the
     > upstream switch.
     >
     > I have placed a 10BaseT hub (old school) in the datapath and
    attempted
     > to capture this information using a linux host running Wireshark,
    but I
     > do not see any flow control information.
     >
     > Is there anything I need to do to the ethernet driver/interface
    in order
     > to capture this traffic using Wireshark?