IBM Support

PI83437: THE LOAD BALANCER FOR IPV4 AND IPV6 CONNECTION TABLE CAN GET CORRUPTED WHEN USING NAT AND HIGH AVAILABILITY

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APAR status

  • Closed as program error.

Error description

  • If both load balancers use the same ephemeral ports within a
    few seconds of a takeover, the connection table of the active
    load balancer may contain invalid information.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  IBM WebSphere Application Server Load       *
    *                  Balancer for IPv4 and IPv6 users with NAT   *
    *                  forwarding                                  *
    ****************************************************************
    * PROBLEM DESCRIPTION: The Load Balancer for IPv4 and IPv6     *
    *                      may fail to forward NAT packets under   *
    *                      heavy traffic.                          *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Packets may be dropped from the servers when using NAT
    forwarding when the returnaddresses reuse port numbers.
    

Problem conclusion

  • The returnaddress was not using unique ports per server which
    could cause the load balancer to have the wrong state
    information for the connection. Code was modified to use
    unique ports per servers for a returnaddress. This eliminates
    the possibility of connection information corruption.
    
    Fix levels:
       8.5.5.13
       9.0.0.6
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI83437

  • Reported component name

    WS EDGE LB IPV4

  • Reported component ID

    5724H8812

  • Reported release

    850

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-06-21

  • Closed date

    2017-08-10

  • Last modified date

    2017-08-10

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

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

Fix information

  • Fixed component name

    WS EDGE LB IPV4

  • Fixed component ID

    5724H8812

Applicable component levels

  • R850 PSY

       UP

  • R900 PSY

       UP



Document information

More support for: WebSphere Application Server
Edge Component

Software version: 8.5

Reference #: PI83437

Modified date: 10 August 2017


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