IC90924: APPLICATION OPTIMIZATION (AO) SELF BALANCING INCREASED LATENCY AND SENDING ICMP FRAGMENTATION REQUIRED

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • When using AO Self Balancing, the active group member may send
    "ICMP fragmentation required" back to the client when trying to
    forward large packets to a different group member.  If the
    "Don't Fragment" flag was set in the incoming tcp packet, the
    connection will also experience additional latency because the
    client will have to retransmit the packet.
    
    This may result in performance degradations.
    

Local fix

  • If the network allows, the MTU of the DataPower interfaces may
    be increased to allow forwarding of packets larger than the
    configured MTU.
    
    This local fix 'may' help in some situations.
    

Problem summary

  • Affected are all users of AO Self Balancing on a 10G or
    1G network interface card.
    
    There was a clash between an Active Distributor group member
    (merging small request packets into bigger ones to forward to
    another self-balanced group member) and the client packets
    having set the "Don't Fragment" flag. This condition prevents
    the targeted member from receiving the merged packet when its
    network interface is configured with smaller MTU than the
    receiving packet.
    
    This fix permanently turns off the packet merging (Large Receive
    Offload), thus lifting the need for a (client restricted)
    fragmentation of the large packets.
    

Problem conclusion

Temporary fix

  • If the network allows, the MTU of the DataPower interfaces may
    be increased to allow forwarding of packets larger than the
    configured MTU.
    

Comments

APAR Information

  • APAR number

    IC90924

  • Reported component name

    DTPWR INTGRAPL

  • Reported component ID

    DP905XI52

  • Reported release

    500

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-03-18

  • Closed date

    2013-04-23

  • Last modified date

    2013-08-27

  • 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

    DTPWR INTGRAPL

  • Fixed component ID

    DP905XI52

Applicable component levels

  • R500 PSN

       UP



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Document information


More support for:

WebSphere DataPower Integration Appliance XI52

Software version:

5.0.0

Reference #:

IC90924

Modified date:

2013-08-27

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