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Re: Dead Connection Detection is ... dead?

From: Alex Gorbachev <>
Date: Fri, 13 Oct 2006 20:05:43 -0400
Message-ID: <>

Actually, I just remebered that there are usually issues with low expire_time because of usually high tcp/ip timout value. I also looked briefly at the note you mentioned and found confirmation there. I also saw this there:
"Note: from version onwards, DCD probe packets are no longer traced in SQL*Net trace files, however DCD packets can be observed using other forms of tracing, such as network sniffer tracing."

Perhaps, that's why you don't see the packets in the trace file?

On 10/13/06, Mark Anderson <> wrote:
> My apparent problem is that my server is not sending DCD probe packets
> to my client even though SQLNET.EXPIRE_TIME=1 in
> $OH/network/admin/sqlnet.ora.
> Oracle server is on Red Hat EL release 3
> Oracle client is on Fedora Core release 3
> Between client and server is a router which is deliberately configured
> to close any connection which is idle for longer than a configured
> length of time (presently 70 seconds, although this is negotiable).
> To keep the connection open by ensuring there was activity on the
> connection every 60 seconds I added the following lines to
> $OH/network/admin/sqlnet.ora:
> Trace files started to appear in /home/oracle. Most, but not all,
> contained a line like:
> [13-OCT-2006 21:29:44:296] niotns: Enabling dead connection detection (1
> min)
> and lines like
> [13-OCT-2006 21:29:44:309] nstimini: entry
> [13-OCT-2006 21:29:44:309] nstimig: entry
> [13-OCT-2006 21:29:44:309] nstimig: normal exit
> [13-OCT-2006 21:29:44:309] nstimini: initializing LTM in asynchronous mode
> [13-OCT-2006 21:29:44:309] nstimini: normal exit
> [13-OCT-2006 21:29:44:309] nstimstart: entry
> Which are described in Note 151972.1 "Dead Connection Detection (DCD)
> Explained" as evidence that DCD is enabled. The trace files without
> these lines were very short.
> I opened a connection to the server from the client (which was otherwise
> idle) using a Oracle DBI script that did nothing but log in and sleep at
> the client. Our network admin monitoring the router could see the
> connection appear between the client host and port 1521 of the server
> host and the 70-second clock start to tick. It counted down to 0
> without resetting, from which I infer that no DCD probe packets were
> sent from the server to the client. Is this inference reasonable? If
> it is, does anyone know why the DCD probe packets weren't sent?
> Thanks in advance,
> Mark
> --

Best regards,
Alex Gorbachev

The Pythian Group
Sr. Oracle DBA
Received on Fri Oct 13 2006 - 19:05:43 CDT

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