Wireshark mailing list archives

Re: TCP out of order segments


From: Steven Ryder <sryder () verticalsearchworks com>
Date: Mon, 2 Jul 2012 16:20:32 -0700

I was doing some searching about Out of Order packets and came across this thread that was apparently posted to this 
list. I didn't see any real answer to it so I'm posting my findings. I hope this is not too old :-/ .

http://www.wireshark.org/lists/wireshark-users/200701/msg00060.html

I can tell you I found the cause of this in my case. I have a Cisco 6509 connected to a Cisco 3560 on a gig port. I saw 
significant Output drops on the 6509 end because the buffers in a 3560 cannot keep up with what a 6509 can push. I did 
a packet capture and found I am getting 100Mbps in Out of Order packets...yuck. The 3560's are not a data center class 
switch and we should not be using them in our case.

The 1st 24 ports of the 3560 all share a 2MB buffer, the 2nd 24 ports share another 2MB buffer. That's not much at all.

Contrast that with the 6509's (using WS-X6748's) and they have a 1.3MB buffer per port and you can clearly see the 3560 
cannot keep up.

All Gig ports are not created equally :-/.

Anyway, I hope this helps.

Thank you,
-Steve




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