Thanks for the interesting feedback - did it require something like wireshark in the end to diagnose? On Mon, Aug 2, 2010 at 9:37 AM, gidhin K. joy <gidhin@xxxxxxxxx> wrote: > > This issue was resolved, Just thought to share so that it will be helpful > for someone else. > > Apparently all the trouble was due to a new juniper firewall installed > which would fragment and drop the traffic that would too big to handle. We > have configured SDU to lesser size - 2048 at client side and all the > queries works just fine with a minor performance hit. > > I am not sure what was the default SDU size, however looks like oracle > connection negotiates and selects the lower SDU size among the server and > client. > ~Gidhin > > On 13 May 2010 00:17, Bill Ferguson <wbfergus@xxxxxxxxx> wrote: > >> I had a somewhat similar experience a few months ago. Without getting >> actual confirmation from Oracle, it somewhat seemed like the security >> on SQL Net traffic was tightened up some with 11g, whereby if >> firewalls aren't specifically allowed to pass SQL Net traffic, they >> seem to do some packet sniffing and this winds up in the traffic not >> getting completely sent to the client (even though the server did send >> it all), so everything gives the appearance of hanging simply because >> the server is waiting on a confirmation from the client and the client >> is still waiting for the data. >> >> However, my problem was the server is running 11.1.0.7 (on Windows), >> while the clients that were experiencing problems were running the >> 10.2 drivers. Even with the newer 11g drivers the problem still >> persisted, but clients using 9.x drivers did not have the problem. >> After several weeks of going around and around with the network folks >> and sending them the Oracle notes from MOS stating exactly what to >> look for and exactly what to do to fix it, I finally had to take a >> computer over to their office and show them the exact error on my >> machine, then let them watch the firewall traffic. After about 30 >> minutes of them fiddling around, one guy finally clicked on a screen >> in the firewall configuration menu that showed the exact setting >> Oracle said need to be changed, they allowed SQL Net traffic, and >> suddenly all of the problems disappeared. >> >> One of the "symptoms" of the incorrect firewall setting was that >> something as simple as "select * from table_name" had the appearance >> of hanging, while a similar connection doing a "describe table_name" >> worked. >> >> I forget which MOS documents I found that explained the exact cuase >> and solution to the problem, but I found them by researching the >> TNS-12535 error that I found in my listener's log file. >> >> Hope this helps some. >> >> -- >> -- Bill Ferguson >> > > -- Niall Litchfield Oracle DBA http://www.orawin.info