Re: Sessions dropping

[Scott Klement <klemscot@xxxxxxxxxxxx>]

> We have had users that have had session drop for no apparent reason. The
> sessions go to a black screen, the 400 job is still out there and it the
> old "session stopped per request from the device" message is in the
> joblog. It seems to happen at approximately the same time every day and
> all of the TCP settings look fine.

Is there something that runs at that time every day?

> The only change to the network setup was a recent change to the DHCP
> service (details of which I do not know)  and even session that are
> configured to go to the actual IP, not the name, drop.

This could be a DHCP issue.   The PC may be having it's lease revoked at
that time every day.

Based on this statement "even session that are configured to go to the
actual IP, not the name, drop"  it appears that you have gotten DHCP and
DNS confused.

DNS takes a name, and converts it to an address.   If something would
change with DNS, it would not affect clients that are connecting directly
with the IP Address.

DHCP, however, is what assigns the PCs their IP addresses (often based on
the Ethernet MAC address) and has nothing to do with the names at all.
If DHCP is making the computers change their IP address, you'll have the
problem that you've described above.   Why?  Because the TCP connection
that the TN5250 session is running in relies on two sets of addresses, one
for the PC and one for the AS/400.  If one or the other of those addresses
changes, the connection will stop working and eventually time out.


> I tested 4 sessions on one PC, two dos telnets to name and IP and two CA
> sessions to IP both and only one session dropped... Per the network
> folks, there is no inactivity/latency setting on the router that these
> go to...

As I said, this could be happening when the DHCP lease is renewed, if the
PC stops communicating with the iSeries for a second, and that happens to
be when the iSeries sends it's keepalive packet, it'll reset.

I was thinking also that the PC might be resetting it's TCP stack at that
time, but if some of the sessions are surviving, then that's not the case.

>
> Any clues?
>

Try changing the DHCP lease time to be an hour or two longer and see if
that helps, or changes what time the disconnects happen.   If they start
happening an hour later, you know that the DHCP lease is where the issue
is.

If that doesn't help, then you may have a hardware problem.   Not sure why
that would happen at a regular interval, but it might be due to a power
fluctuation or something that happens at that time every day.

That's all I can think of, right now.