Interesting HP-UX modem problem?

[James Pethigal_1]

Interesting modem problem?

I'm not really sure what forum would be best for this issue - I don't believe it's a hardware problem.

Details:

HP-UX 11.0
US Robotics 56k Modem
Device File Name /dev/ttyd2c9
Type Modem
Hardware Path 8/20/5/1
Port Number c9
Speed (baud) 115200_8n1

8/20/5/1 eisa_mux0 HP J2483A - 64/64 RS-232 MUX

with WYSE 60 emulation

I can (or our ERP vendor) dial into our system, log in just fine & can stay connected for hours while working.
But... the second I do anything very graphic intensive - we get disconnected.
This includes firing up our ERP app. in WYSE 60 & running one of the graphically intensive screens -or- from root viewing or tailing a large log file.

I've swapped out the modem, tried several different ports on the MUX.
Do I have the baud set to high?
No issues if it's a local network telnet connection.

Any suggestions or help would be appreciated!
(I hope this isn't something bonehead on my part :-)

Have a good New Year,
James

[avsrini]

Hi James,
This is really interesting.
Have you checked reducing the speed of the modem?.
What i feel is, when you have more data flowing on the link, and if link is not too good,
may be too many error corrections happening and the link is
disconnecting.
In this case, you can try reducing the modem speed to lower one, and give a try.

Srini.

[Bill McNAMARA_1]

I used to work on a networking product that'd do something like this!! (not a modem)

When you say disconnected, does your Xsession close or does the modem dial in session disconnect.

If it's your modem dial in session disconnecting I suspect you've got a lan/driver/firmware problem, and I'd have no real input to give other than that, however, if it's the xsession (which I suspect since I came across this type of problem already), upgrade your client (browser) Xserver software and the x software on your host while you're at it.

You should look at nettl tracing in order to determine the real cause (x graphics are sent in xprotocol)

What is your X display hardware btw?

Good luck,
Bill

[Rory R Hammond]

It might be a flow control problem. Have not have had to use mux and modems for about 5 years. On the K box's I had, 19200 was about the fastest I could hope for.

US Robotic modems have some diagnostic cabilities.
+++ati6 should bring up a screen that tells you the disconnect reasons, which might give you a clue.

Rory

[Chris Vail]

I had a similar problem earlier this year. I could fix it only by slowing it down--to 9600 BAUD! Thats not much help, I know. You might check to see if flow control is in hardware or software, and whichever it is, switch it. Thats the only thing I can think of.


Chris