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Connections to clocks from AS/400 drop intermittently

We have several Intermec time clocks at remote locations connected through our WAN to our AS/400. A week ago our main router was upgraded with new software. Now the connections to the clocks from the AS/400 keep dropping intermittently.

We believe it is on the network side, not the AS/400, but have not been able to determine this.

Could you give us some suggestions to help locate where the problem is?

Is the AS/400 connecting to the clocks or vice versa? Will it ever connect to a remote site? If it does connect, when will it drop (is it arbitary or after a certain idle time)?

Member feedback:
The main thing I was looking for was the best way to start diagnosing these types of problems. The clocks connect to the AS/400. It will connect to a remote site, and it seems to drop more often around the end of the work day.

As a side note, at 5:30 p.m. I noticed a few TCP/IP connections going to close-wait status, some ending, and more being generated with an average of about 6. When I received notice that connections were being lost, I checked netstat for close-wait connections. There were over 40 and all of them were from Management Central –- monitors on the systems. With this number of close-wait connections, TCP/IP will drop connections as we saw with the WebSphere problem connections, which were doing the same thing. I have opened a PMR with IBM, and in the meantime I have shut down Management Central until we determine if this was the cause or not.

Thanks you for your help.

Shahar's response:
It may be due to some station trying to connect many times. In order to further investigate it, I would consider setting up an IP journal, which is part of journal filter. This is a little heavy on the machine, but it will log all the required events.

You can read instructions for setting up IP filter journaling.

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