Most/All of the conversations follow the following pattern absolutely
consistently:
AS400 sends data.
Very quickly (<2ms) the Stratus acknowledges and replies with its own
data.
The AS400 then takes up to 500ms to send more data. It's TCP stack
(correctly) times-out after 20-40ms and sends an acknowledgement, but
the next data is not sent for 150-450ms after that.
(To see this, create a colourisation filter of "tcp.analysis.ack_rtt >
0.01", set the time display option to "seconds since previous frame",
follow any TCP stream and close the stream window, (this sets up the
correct display filter to see only one conversation.))
I would guess that this is a command-response protocol, and that the
AS400 is taking far too long to process data and return a result.
I don't have a lot of experience with the TCP graphs, but all the (port
22211) conversations have graphs of the same shape. This indicates to me
that there is some overlying factor that is affecting all of them.
(Processor load maybe?)
There is another conversation in the file between the AS400 and
10.11.100.58 that is strikingly different and seems to be working fine.
Unfortunately the capture only has half of the conversation, so we
cannot see the AS400 latency times.
--
Richard Urwin, Private
"No 9000 series computer has ever made a mitsake or corrubiteddatatato."
-----Original Message-----
From: Mark Holloway [mailto:mholloway@xxxxxxxxxxxxxxxxxxx]
Sent: 22 May 2003 20:03
To: ethereal-users@xxxxxxxxxxxx
Subject: [Ethereal-users] Viewing this capture to help find the problem
I am having HUGE problems with TCP communications between an AS400 and
Stratus (running VOS). The Stratus has data it is sending to the AS400
on TCP port 22211. I have confirmed the category 5 cable is good, the
switch ports are good, and everything is set for 100 Full Duplex.
I have posted a capture that is available for download (11MB) at
http://www.markholloway.com/arclight.cap
I setup a mirror port on my Foundry switch and filtered the capture for
host 10.11.2.4.
10.11.2.4 = AS400
10.11.2.5 = STRATUS
I appreciate any help or feedback in regards to troubleshooting. I have
been trying to resolve this but I am stuck! I had another guy run
Sniffer on this capture and the Expert reporting shows long ack time and
retransmitted packets. Im new to Ethereal, so Im not sure of the best
method to search for anomalies.
Regards,
Mark Holloway
Sr. Network Engineer - Arclight Systems, LLC
702-253-3861 // mobile 702-349-6170
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