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Thread: drop connection

  1. #1
    Join Date
    Oct 2003
    Posts
    15

    Unanswered: drop connection

    We have this 8.1.6 production database running in our DMZ area. The end user of
    our application keep complaining their connection get dropped intermittently
    for no reason. I test out the connection from a couple of PCs in our intranet
    by connecting to this database in the DMZ area and found out the connection
    gets dropped periodically also. From the test connections I ran, it can last
    from 45 minutes to 6 hours before it gets dropped. I don't want to turn the
    trace on because this is too random and it might pose a negative impact on the
    database server by leaving trace on too long. Our network people ran some
    sniffer capture and detect that the firewall is dropping the connection to the
    database in the DMZ area because it is receiving bad TCP packets from the
    Oracle software.
    I also include below the description of this problem from the developer who
    interacts with our clients directly since he has the first hand information,
    while I'm the backend DBA:
    Users from our intranet work with a web based interface, normally the software
    client is MS Internet Explorer.
    On the interface they have some screens that allow them to read, edit, and
    insert data into tables located in the server outside the firewall.
    From time to time they get the following two error messages when trying to
    connect to the outside server
    ORA-02068: following severe error from OPSWEB ORA-03113: end-of-file on
    communication channel
    Or
    ORA-02068: following severe error from OPSWEB ORA-03114: not connected to
    ORACLE

  2. #2
    Join Date
    Jan 2004
    Posts
    370
    You forgot to post the O/S version you are running Oracle on.

    This may not necessarily be a network issue.

    Have you checked the alert log?
    Have you checked user_dump_dest for any trace files?

  3. #3
    Join Date
    Oct 2003
    Posts
    15
    O/S WINDOWS NT

    i checked it already . i opend tar with oracle as well and according to them it is network issue.

  4. #4
    Join Date
    Jan 2004
    Posts
    370
    So there are no errors in any of the database or sqlnet logs?

    Does the failure occur during a database operation or while the session is idle?

    I don't know your setup so some questions may not be relevant, like does it happen for everyone? Only users outside the firewall?, etc.

  5. #5
    Join Date
    Oct 2003
    Posts
    15
    Originally posted by SkyWriter
    So there are no errors in any of the database or sqlnet logs?

    Does the failure occur during a database operation or while the session is idle?

    I don't know your setup so some questions may not be relevant, like does it happen for everyone? Only users outside the firewall?, etc.

  6. #6
    Join Date
    Oct 2003
    Posts
    15
    failure occur when session is idle.
    there no errors in sqlnet.logs

    Originally posted by SkyWriter
    So there are no errors in any of the database or sqlnet logs?

    Does the failure occur during a database operation or while the session is idle?

    I don't know your setup so some questions may not be relevant, like does it happen for everyone? Only users outside the firewall?, etc.

  7. #7
    Join Date
    Jan 2004
    Posts
    370
    >Our network people ran some sniffer capture and detect that
    >the firewall is dropping the connection to the database in the
    >DMZ area because it is receiving bad TCP packets from the
    >Oracle software.


    If the connection is idle, the Oracle session should just sit on a Waiting for "SQL*Net message from client" wait event

    Why are any packets (never mind bad packets) being sent over an idle session?

    The only thing I can think of is Dead Connection Detection to check the client is still alive.
    What is the value of sqlnet.expire_time in the sqlnet.ora on the server?

    Also, as a matter of interest, how many network cards do you have on the server?

  8. #8
    Join Date
    Oct 2003
    Posts
    15
    this is the value
    sqlnet.expire_time=1440

  9. #9
    Join Date
    Jan 2004
    Posts
    370
    An expire time of 1440 minutes = 24 hours
    That doesn't explain away the bad packets since the connection gets dropped long before the any probe packets would be sent.

    The bad tcp packets are being sent by the Oracle software - the database, yes?


    Why does your firewall break the connection?
    Is it because it has some form of intrusion detection and automatically drops the connection when it receives bad packets?

    How many network cards are in the server?

    Can you also check if an idle_time or connect_time limit is set in the user profile?

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