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Is there IP fragmentation by a MTU mismatch between the NAS and NFS client?

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622
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Public
Votes:
6
Category:
ontap-9
Specialty:
nas
Last Updated:

Applies to

  • ONTAP 9
  • NFS
  • MTU (Maximum Transmission Unit)
  • MSS (Maximum Segment Size)
  • IP fragmentation

Answer

  • No, as long as the larger MTU (9000) never sends anything larger then the smaller MTU (1500), there will be no IP fragmentation
    • The NFS client is the only side who initiates the TCP connection (three-way handshake) and the MSS will limit the size of the frames on the NAS side, thus there will be no IP fragmentation

Additional Information

  • The IP fragmentation on the NAS (ONTAP) side can be checked by looking at (look for the keyword "fragments")
    • autosupport: NETSTAT_S.TXT
    • ::> system node run -node * -command "netstat -s -p ip"
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