We have found what appears to be a bug (or undocumented feature) in 
SetUDPChecksum where packets sent into this element are somehow discarded.  In 
the attached config, you will see an ElementClass called FixChecksumsDebug 
which counts packets into each checksum fixer and counts packets out the other 
side.  We have found that, under specific circumstances, packets sent into 
SetUDPChecksum never come out the other side.  This is true of the latest 
version from SVN.

As to the particular situations for this problem, it seems to happen only with 
fragmented packets.  In a set of packet fragments, the first portion (offset 
+0) always seems to be discarded when going through SetUDPChecksum.  There is 
no indication that I have found as to the reason for the discard.

Has anyone else seen this issue?  Does SetUDPChecksum have a second output that 
is undocumented?  Any suggestions?

Thanks,

Robert Ross

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