Re: TNS Connection Lost

Ed Jennings <jenningse_at_mindspring.com> wrote in article <3454EA4A.23FC_at_mindspring.com>...
> About two weeks ago I enabled the cost based optimizer in a 7.3.2.3
> instance. The next day people started reporting sporadic problems
> getting into the DB via SQLnet. I have been able to reproduce it myself
> from both unix and windows. As I said it is sporadic. I fail once, but
> retry immediately and get in. The sqlnet.log file left in my home
> directory states:
>
> "Fatal OSN connect error 12547"
> "TNS-12206: TNS:received a TNS error during navigation"
> "TNS-12547: TNS:lost contact"
> "TNS-00517: Lost contact"

I doubt that this have anything to do with turning on cost-based optimising. My guess is that it's either a network problem, or a problem with your server. You did not mention the server OS you're using, but if it's Unix look at the network statistics (run "netstat 5" to sample stats very 5 seconds). You're probably running an ethernet LAN? Go to the hub and do a quick visual check on the number of collissions on the hub. You are not by any change breaking ethernet rules with cascading network segments? From first glance this looks to me like a TCP connection timeout - i.e. during the tns handshaking the client send a packet to the listener and fails to receive a response.

The best way to approach the problem IMHO will be to turn on SQL*Net client logging and tracing on the listener.

regards,
Billy Received on Tue Oct 28 1997 - 00:00:00 CST