Re: Sessions dropping -- MIDRANGE-L

I once had a problem where a twinax printer on a long (2000') cable run
dropped offline *every* day at around 3:00 pm.

After crawling around in the overhead of the factory and tracing the cable
out, I found that it ran *directly* over a very large TIG welder, which they
powered up and started using every day at (you guessed it) 3:00 pm.

In this case, rerouting the cable fixed the problem.

Steve

----- Original Message ----- 
From: "Scott Klement" <klemscot@xxxxxxxxxxxx>
To: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx>
Sent: Wednesday, September 10, 2003 5:21 PM
Subject: Re: Sessions dropping


>
> > 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.
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