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Spirent TestCenter: How to check Spirent TestCenter sequence errors using capture (pcap) file?


One possible way to verify the sequence errors is to use Wireshark and export the summary section to a .csv file and import them into a spreadsheet program to analyze the Sequence Numbers (SN) of the streams.

  • Open the pcap (see attached pcap) in a version of Wireshark that has a Spirent Signature Field dissector
    • Spirent version available on the CSC: version 1.10.3
    • General version available from Wireshark: version 3.4.4 (and higher)
  • Add a couple of columns for the Stream ID (stcsig.streamid) and Sequence Number (stcsig.seqnum).
    • see SOL12911 - Wireshark: How do I add a column in the packet summary section to display a Spirent TestCenter Signature field?
  • Export the summary section of the pcap
    • Export Packet Dissections -> As CSV...
    • Save All packets, packet summary line, and include the column headings (see attached .csv).
  • Use a spreadsheet program to check for drops (e.g., Excel)
    • Open the .csv, select all the cells, and add a filter
    • Under the Stream ID column, select one of the stream IDs
    • In an unused column, add a formula to check to see if the Sequence Number (SN) of a packet is one more than the one before it. For example:
           =IF(I5=(I3+1), 0,1)
      That is, if the SN of the 2nd packet is 1 more than the SN of the 1st packet, make it a 0 (no drop occurred), else make it a 1 (a drop occurred).
      The idea is if they are all 0's, there is no drop.
    • Copy that formula down to the rest of the cells.
      • Note we are not guaranteed that rows being skipped are always the same. So, a copy down of the formula won't necessarily be accurate.
      • So, it might be easier, after filtering out the stream ID you are interested in, to copy the records to another worksheet.
      • For example, in the attached .csv,
        • Stream ID 65537 has some rows that are consecutive, whereas
        • Stream ID 65536 always skips a row.
    • You can use the summation or subtotal function at the bottom of that column, to see if it is non-zero. If so, then there are drops.
  • The attached .pcap and .csv has two streams
    • Stream ID 65536 has 9 dropped frames
    • Stream ID 65537 has 0 dropped frames
Attachment Description
Pcap that can be used as an example

Attachment Description
.xlsx with a formula added for stream ID 65536, and stream ID 65537 on a second sheet in the workbook

Attachment Description
.csv exported from Wireshark

Product : Spirent TestCenter