Wireshark-users: Re: [Wireshark-users] Packets not captured, tcp acking lost segments. Large pack
Thanks Martin
I read up on LSO. It explains how these >4K packets are appearing
Yes I am running Wireshark on the application server. I had a hard time
installing it on my switch!! No CD-rom drive!! :)
(I am not sure what you mean by 'Server Switch')
But why is MS Net Mon seeing these large packets?
Wireshark is providing misleading information and I don't think i'm the only
one that is suffering major confusion.
I think my self lucky as I have witnessed the packets in NetMon.
Most users on the net seem to have presumed that packets are being lost!
Wireshark will see the large segments go out.
But its not...?
You might want to capture on your server switch rather than the server
to avoid seeing this.
I don't want to avoid packets, I want to see the packets!
Cheers
Michael.
----- Original Message -----
From: "Martin Visser" <martinvisser99@xxxxxxxxx>
To: "Community support list for Wireshark" <wireshark-users@xxxxxxxxxxxxx>
Sent: Friday, January 07, 2011 1:46 PM
Subject: Re: [Wireshark-users] Packets not captured, tcp acking lost
segments. Large packets
It sounds like you are capturing traffic on the server rather than the
wire. If your server NIC and driver does Large Segment Offload, the
segmentation is done by the NIC, which allows the transfer from your
kernel to the NIC do be done in larger chunks, meaning a more
efficient transfer. Wireshark will see the large segments go out.
You might want to capture on your server switch rather than the server
to avoid seeing this.
Regards, Martin
MartinVisser99@xxxxxxxxx
On 7 January 2011 11:25, Michael Lynch <michaellynch511@xxxxxxxxx> wrote:
Hi All
I think I've found something everyone may be interested in...
In wireshark I am monitoring traffic of a SOAP application.
Upon transfer of a BLOB, wire shark is showing many "Tcp ACKed lost
segment"
packets.
On top of this there is no evidence of any of the SOAP data, other than
the
initial header.
Now I've search for this lost segment business, and no forums really seem
to
have much of a solution other than perhaps disabling sequence analysis.
However I think I have found the problem, but I have no understanding of
the
whats and whys.
In Microsoft Net Mon, the data packets ARE THERE!!!
i.e
Sent packet: Captured Frame Length = 4434, Media Type = Ethernet...
Continuaion to packet #76.
Received packet: Ack
The received packet is the only packet that shows up in Wireshark! (I
have
cross referenced the Packet ID)
Wireshark is NOT COLLECTING LARGE PACKETS!!
I have no idea how packets THAT LARGE got onto the wire IN THE FIRST
PLACE!!
What is going on??!! :)
Cheers
Michael
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