IDS Forum

Re: Question about Keep-Alive Option

Posted By: Martin Fuerderer
Date: Friday, 1 September 2006, at 5:25 a.m.

In Response To: Question about Keep-Alive Option (Quman)

Hi,

for the first question you better ask some "OS buffs".
Last time I checked on these parameters was more than 6
years ago ...

[ Usually there are two parameters to it:
- the initial timeout, default value is often 2 hours,
- the timeout for repeated attempts, default is often 1 minute (I
think).

After the initial timeout, 10 attempts are made to get a response
from the connected counterpart. If there is still no response after
these 10 attempts, then the connection is considered dead.
TCP will close the connection. With that the overall time for most
default configurations is 2 hours and 10 minutes.

Since the TCP implementation usually is part of the OS,
specifics (parameter names, default values, etc.) may vary
among different OSs.
]

> (2) "network service" is a process in Informix or in our OS?

Hmm. It is not a process in the sense of a process with
a process ID running on a UNIX system. That means you will
not find anything using the "ps" system utility.

This is a "service" in the sense of a functionality implemented
in the TCP layer of the network layers (see the 7 layer
OSI model). Therefore the functionality is transparently used by
the process that has an open TCP/IP connection.

While in general the configuration of the TCP Keep-Alive is
done in the OS and usually for the whole UNIX system
(hence often via kernel parameters), the functionality is used
in individual processes that have TCP/IP network connections.
Usually the application does not even have to know about
this TCP Keep-Alive thing, because it is implemented inside
the TCP network layer.

You can read more about TCP Keep-Alive in books
like Steven's "Programming in the UNIX Environment".

I hope this makes things a bit clearer.

Regards,
Martin
--
Martin Fuerderer
IBM Informix Development Munich, Germany
Information Management

Informix URLs list: http://home.arcor.de/mfu1/informix/urls.html
IBM Information On Demand Global Conference
October 15-20, 2006, Anaheim, California
see http://www.ibm.com/events/informationondemand

ids-bounces@iiug.org wrote on 31.08.2006 18:46:48:

>
> I copied a paragraph from Admin Guideas following,
>
> IBM Informix Dynamic Server Administrator's Guide
> Previous Page | Next Page | Index The Database Server >
> Client/Server Communications > The sqlhosts Information >
> Connectivity Information
>
> Keep-Alive Option
>
> ........................
> When a connected client and server are not exchanging data and the
> keep-alive option is enabled, the network service checks the
> connection periodically. If the receiving end of the connection does
> not respond within the time specified by the parameters of your
> operating system, the network service immediately detects the broken
> connection and frees resources.
> .......
>
> My question is,
> (1) in above statement "...specified by the parameters of your
> operating system...", what is the names of the parameters in the OS ?
>
> (2) "network service" is a process in Informix or in our OS?
>
> Program Name: onstat
> Build Version: 10.00.UC4
> Build Number: N204
> Build Host: ibm6c1b
> Build OS: AIX 5.2
> Build Date: Fri Nov 18 23:37:26 CST 2005
> GLS Version: glslib-4.00.UC7
> fqu@dolly $
>
> Thanks,
> Quman
>
>
*******************************************************************************

> Forum Note: Use "Reply" to post a response in the discussion forum.

Messages In This Thread

• Question about Keep-Alive Option
  Quman -- Thursday, 31 August 2006, at 12:46 p.m.
  • Re: Question about Keep-Alive Option
    Eric Rowell -- Thursday, 31 August 2006, at 1:55 p.m.
    • Re: Question about Keep-Alive Option
      Rajib Sarkar -- Thursday, 31 August 2006, at 2:16 p.m.
  • Re: Question about Keep-Alive Option
    Martin Fuerderer -- Friday, 1 September 2006, at 5:25 a.m.

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