Printer FriendlyEmail Article Link

Spirent TestCenter: How to send IPv4 fragments with raw streamblock?

Environment/Versions
  • Spirent TestCenter
  • IP Fragmentation using Raw streamblocks
Answer
  •  When trying to send fragment packets, the "fragment offset" value should be right, or else DUT or wireshark can't reassemble the packets.‚Äč
    • The unit of "Fragment offset" is 8 bytes.
  • So if the frame length of each fragment is 1514(without FCS), the data length in the IP packet is 1514 - 14(Ethernet Header) - 20(IP Header) =1480
    • "Fragment offset" of the second fragment should be 1480/8 = 185
  • So the value of "Fragment offset" be set in the STC should be 185 (For second fragment), 370(For the third fragment) and so on
  • Note :  All fragments must have the same Identification field value in the IP Header.
  • Click here for sample video
    • you can use any ftp app to retrieve this file (below example at a windows command prompt)
    • C:\Users\example001\Downloads>ftp kbfiles.spirent.com
      Connected to dmzcalcsftp01.spirentcom.com.
      220 (vsFTPd 3.0.3)
      200 Always in UTF8 mode.
      User (dmzcalcsftp01.spirentcom.com:(none)): anonymous
      230 Login successful.
      ftp> get /SpirentTestCenter/kb_articles/FAQ11157/Training_IPv4-n-IPv6_fragments.zip
      200 PORT command successful. Consider using PASV.
      150 Opening BINARY mode data connection for /SpirentTestCenter/kb_articles/FAQ11157/Training_IPv4-n-IPv6_fragments.zip (439863029 bytes).
      226 Transfer complete.
      ftp: 439863029 bytes received in 10.65Seconds 41282.31Kbytes/sec.
      ftp>

Product : Spirent TestCenter,Spirent TestCenter,IP,PGA