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Concurrent users on OpneVMS


Concurrent users on OpneVMS

Hi all,

I have a problem with concurrent sessions on the system (via telnet).

I use Putty and Putty connection manager (wich has nothing to do with the problem, I think). When I have just one session, there is no problem at all, but if I start two, three or four session, there is some kind of time-out and after some minutes without activity all connections except the first one are reset. I have tried with Putty "keep alive" option but it does not work.


I didn't use to have this problem and as far as I know nobody has changed the system configuration (but it is possible), maybe is something related with win7, my problems have started when I change my computer, but it does not make too much sense to me.


Any idea? I'm getting crazy.


Thanks in advance.

Andy Bustamante
Honored Contributor

Re: Concurrent users on OpneVMS

On the OpenVMS systems, what TCP/IP product are you using?  OpenVMS version?  Is this a local or WAN connection?

If you don't have time to do it right, when will you have time to do it over? Reach me at first_name + "." + last_name at sysmanager net
John Gillings
Honored Contributor

Re: Concurrent users on OpneVMS



   There are numerous places that a connection can be broken. You'll need to conduct some targetted experiments to work out where it's happening. An example, in my environment there are numerous independent subnets with firewalls in between. If I have a connection that goes between subnets, the firewall will break a connection after some period of activity. To counter this, I have some code which examines the route ($ MCR TCPIP$TRACEROUTE 'F$TRNLNM("SYS$REM_NODE")' ) checking for the IP addresses of firewalls. If one is found, a /NOWAIT subprocess with ^Y disabled is created which spits out a timestamp every 20 minutes.


  Since you say a single connection is unaffected, this may not be your issue (or it may just be that your "primary" connection is used enough that it's not affected). Start some experimental sessions with known login times & periods of inactivity and examine the accounting information to see if there is a consistent timeout. For that matter, what is the termination status of the lost processes? Also examine the routes to see what else may be in the path.

A crucible of informative mistakes
Occasional Advisor

Re: Concurrent users on OpneVMS

We able to stop idle telnet sessions from dropping via advice from Micheal Yu, originally in
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=950981 ...

Michael Yu   Sep 6, 2005 02:21:36 GMT  10 pts  
If you do not want to modify the tcp defaults for all tcp connections, you can use the following tcpip command.

TCPIP> set serv telnet/proto=tcp=probe=600
TCPIP> set serv telnet/proto=tcp=drop=10
TCPIP> disable service telnet
TCPIP> enable service telnet

Remember disabling service telnet will destroy all existing telnet connections.

The following will appear in the tcpip show service telnet/full.

TCP options: Delay
Drop_count: 5 Probe_timer: 600

Michael Yu   Sep 8, 2005 08:56:31 GMT  2 pts  
probe_count is the number of seconds between probes for idle connections.

If there is no reply from the remote, then the probe will be retransmitted according to normal TCP retransmissions, up to a total of drop_count seconds and the connection will be closed.