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IT22185: ON A NAT ENVIRONMENT WITH THE REGISTRY VARIABLE DB2_HADR_NO_IP_CHECK TURNED ON, HAS ISSUES WITH MULTIPLE HADR STANDBYS.

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APAR status

  • Closed as program error.

Error description

  • Currently DB2 does not support DB2_HADR_NO_IP_CHECK with
    multiple standbys.
    It would require a change to the DB2 product.
    
    The principle standby has address X, but it sits behind a router
    which does NAT to translate address X to Y.
    The standby makes a connection to the primary.  This forms a
    TCP/IP connection via a 3-way TCP handshake.  During this
    handshake and all subsequent messages, the principle standby
    constructs a network packet with TCP and IP headers.  These
    headers contain the address X as the source address.  When the
    packet goes through the router, source address X is changed to Y
    in the TCP/IP header.  The primary receives these packets with a
    TCP/IP header indicating that it was sent by source address Y.
    When the primary responds, it creates a TCP/IP header indicating
    Y is the destination address.  When this reaches the router, it
    changes the destination address from Y to X and forwards it to
    the standby.
    
    After the TCP/IP connection forms, the primary prints the
    address of the connection.  This comes from the TCP/IP header,
    so it is address Y.  Later on, the primary receives the full
    handshake message.  This looks at the source address in the
    handshake message, which is address X. Therefore the addresses
    do not match.
    
    The solution requires an update to the product by IBM and a
    special configuration by the customer.
    
    When a remote host is behind a NAT, then the local host should
    be set up with the following configuration ...
    - Set DB2_HADR_NO_IP_CHECK to true
    - Configure HADR_TARGET_LIST using the address of the NAT
    router.
    - Configure HADR_TARGET_LIST using the port specified by remote
    host's HADR_LOCAL_SVC.
    - Configure port forwarding on the NAT router so that any
    message sent to the router's HADR_LOCAL_SVC will be forwarded to
    HADR_LOCAL_ADDR.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1 Mod 3 Fix Pack 3 or higher               *
    ****************************************************************
    

Problem conclusion

  • First fixed in Db2 11.1 Mod 3 Fix Pack 3
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT22185

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-08-29

  • Closed date

    2018-03-19

  • Last modified date

    2018-03-19

  • APAR is sysrouted FROM one or more of the following:

    IT18608

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB10 PSN

       UP

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
19 March 2018