Windows Server

Guest · Posted: Tue Sep 20, 2005 8:52 pm Post subject: 3270 Timeout

We have several battery-operated carts with wireless laptops that use a
3270 emulator (Zephyrcorp's PassPort TN3270) to connect to our
mainframe via TN3720 and our HIS server. The laptops power down after
20 minutes, and this caused problems with the 3270 session getting hung
(I can't remember if it was at the mainframe or the HIS server),
requiring the users to call the Help Desk to reset the session. So we
set the TN3270 Idle Timeout to 17 minutes, which solved the problem for
many months.

Recently, the problem (at least, the symptoms) resurfaced, and in
researching it, I couldn't seem to get this idle timeout to kick in. I
noticed that the HIS server had been up since December, 2004, so I
figured something had got it's nose out of joint, and rebooted the
server. After rebooting, I still can't get a TN3270 session to time
out no matter how long I leave it inactive. Maybe I'm doing something
wrong, I don't know. I want to do this to prove whether the timeout is
working or not, so if the problem comes up again, I'll know to look
elsewhere.

Neil Pike · Guest

Robert - I'd run a sniffer trace or a TN3270 trace to see what's going on.
Could someone have amended the emulator to send keystrokes as keep-alives not
realising the adverse effect it would have on the laptops?

Neil Pike. Protech Computing Ltd
Microsoft SNA/HIS MVP

Charles Ezzell (MSFT) · Guest

I would verify that the idle timeout is still set to 17 minutes. Also, where
any changes made to the client, or updates <patches> to the server?

And, to make things more "complicated", we just identified a problem where
Windows 2003 returns a different return code than Windows 2000 when we call
GetQueuedCompletionStatus, which caused TN sessions to not be "disconnected"
when the timeout was "hit". This is currently going through code review
right now.

Traces (netmon and TNServer) would help greatly.

HTH,
Charles

"Neil Pike" <neilpike@compuserve.com> wrote in message
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Neil Pike · Guest

Charles - is there a KB number on that one yet?

Charles Ezzell (MSFT) · Guest

KB will be 908232, but it may be a while before it shows up.

--
HTH,
Charles Ezzell
Microsoft

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"Neil Pike" <neilpike@compuserve.com> wrote in message
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Neil Pike · Guest

Thanks Charles - will make a note to look in a few weeks

Neil Pike. Protech Computing Ltd
Microsoft SNA/HIS MVP

Guest · Posted: Fri Sep 23, 2005 8:51 pm Post subject: Re: 3270 Timeout

Thanks for the replies. I have verified that the timeout is still set
to 17 minutes. The TN3270 client does have a "keep-alive" feature, but
it hasn't been implemented on any of these workstations.

The server is Windows 2000 - always has been. That's what's so odd -
nothing has changed.

Could someone verify for me - IF I have the timeout set to 17 minutes,
and IF my emulator isn't sending "keep-alive" packets, if I leave a
session up for more than 17 minutes, should the server disconnect it
automatically (one would think so)? In that case, what should I see at
the client session - blank screen? VTAM logon screen? If I press a
key on the client, should that reactivate the session - i.e. should I
then see the VTAM logon screen?

Stephen Jackson [MSFT] · Guest

Robert,

If the TN3270 Idle Timeout is set to 17 minutes, the TN3270 Server will
disconnect the TN3270 session if it is idle anywhere from 17 - 34 minutes
due to how the Idle Timeout timer works. What happens is that at the end of
the Idle Timeout period (17 minutes in this case), the TN3270 Server checks
to see if there has been any activity for that session over the previous 17
minutes. If there has been activity, the timer is rest. The next check is
done again 17 minutes later. If the client had sent data to the TN3270
Server 0.5 seconds into the initial 17 minute timout window, the TN3270
Server would not disconnect the client at the first timer check. Therefore,
the total idle time before this client is disconnected would be 33 minutes
59.5 seconds.

If you are not seeing the clients disconnect, you could enable a Sniffer or
Network Monitor trace to capture the traffic between the TN3270 Server and
the TN3270 Client to see what is flowing during this time. You might also
want to enable the TN3270 traces on the HIS server using the SNA Trace
Utility (snatrace.exe) to coordinate with the network trace.

When the TN3270 disconnects an idle TN3270 session, an event similar to the
following will be logged in the application event log:

Event ID: 603

Source: TN3270 Server

Description:

TN3270(E) session with client at TCP/IP Address (port TCP/IP port) using LU
TN3270 LU Name terminated abnormally because:

TN3270E Service Error 503

Session terminated due to inactivity.

The LU in SNA Manager should show an "Available" status once it is
disconnected.

--
Stephen Jackson
Microsoft® SNA/HIS Support

Please do not send e-mail directly to this alias. This alias is for
newsgroup purposes only. This posting is provided "AS IS"
with no warranties, and confers no rights.

<robert.macnutt@nghs.com> wrote in message
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John Chambers · Guest

Robert,

There may be a different way to accomplish what you are trying to do. By
default TCP will send keepalives from the HIS server to the laptop every 2
hours. If the laptop does not respond (like when it is asleep or out of
range) it will then reset the LU on the HIS server. If you change the
keepalive value from 2 hours to 1 or 2 minutes, the HIS server will then
reset the LU within a minute or two of the laptop going to sleep. Check out
KB183786 for the details. This is the way I have all of my HIS servers
configured. A side benefit is that you could put the Idle Timeout back at a
higher value, thus not disconnecting your users if they have the laptop up
and running but just aren't using the TN3270 emulator for a while.

John Chambers

<robert.macnutt@nghs.com> wrote in message
news:1127241541.372010.90210@g14g2000cwa.googlegroups.com...
We have several battery-operated carts with wireless laptops that use a
3270 emulator (Zephyrcorp's PassPort TN3270) to connect to our
mainframe via TN3720 and our HIS server. The laptops power down after
20 minutes, and this caused problems with the 3270 session getting hung
(I can't remember if it was at the mainframe or the HIS server),
requiring the users to call the Help Desk to reset the session. So we
set the TN3270 Idle Timeout to 17 minutes, which solved the problem for
many months.

Recently, the problem (at least, the symptoms) resurfaced, and in
researching it, I couldn't seem to get this idle timeout to kick in. I
noticed that the HIS server had been up since December, 2004, so I
figured something had got it's nose out of joint, and rebooted the
server. After rebooting, I still can't get a TN3270 session to time
out no matter how long I leave it inactive. Maybe I'm doing something
wrong, I don't know. I want to do this to prove whether the timeout is
working or not, so if the problem comes up again, I'll know to look
elsewhere.

Guest · Posted: Mon Sep 26, 2005 8:51 pm Post subject: Re: 3270 Timeout

Many thanks for all the great info. The problem seems to have
disappeared since rebooting the server, so I won't be spending a great
deal more time on it right now, but I'll file all this away and
research it further as time permits

Robert

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