When you use the netstat -s command to display per-protocol statistics in Windows Vista, the Reassembly Failure counter displays a value that is higher than expected. The value from the Reassembly Failure counter may even be as high as the value from the Reassembly Successful counter.

For example, the “IPv4 Statistics” section of the netstat -s command output may resemble the following:

IPv4 Statistics
  Packets Received                   = 6268757
  Received Header Errors             = 0
  Received Address Errors            = 12517
  Datagrams Forwarded                = 0
  Unknown Protocols Received         = 2
  Received Packets Discarded         = 53576
  Received Packets Delivered         = 6403107
  Output Requests                    = 3577979
  Routing Discards                   = 0
  Discarded Output Packets           = 485
  Output Packet No Route             = 2
  Reassembly Required                = 3095
  Reassembly Successful              = 1534
  Reassembly Failures                = 1534   ------------>Not True
  Datagrams Successfully Fragmented  = 2268
  Datagrams Failing Fragmentation    = 0
  Fragments Created                  = 4539