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Spirent TestCenter: How do I configure a static value for the IP identification ID field of the IPv4 header?

Environment/Versions
  • Spirent TestCenter
Answer
The IP Identifier field increments for every packet; ID field in IP header is automatically incremented by hardware and associated with the checksum header.  
Below are two methods to meet the requirement of keeping the IP ID:

Method 1:
  1. Configure a VFD on the Identifier field, initial value 0 (for constant IP ID = 0), step 1, count 65536 (see screenshot). This is limited to a total of 65536.
  2. To increase the number of packets:
    1. Configure StreamBlock Scheduler to Rate Based
    2. Duration Mode to Burst
    3. Configure the load to 1/10 of the default 10 % = 1.0 %
    4. Duplicate the StreamBlocks 9 times for a total of 10 StreamBlocks
    5. Increase the burst size 65535 X 10 that will increase the number to 655350
  3. If more required, instead increase the number of packets:
    1. Configure StreamBlock Scheduler to Rate Based
    2. Duration Mode to Burst
    3. Configure the load to 1/1000 of the default 10 % = 0.01 %
    4. Duplicate the StreamBlocks 999 times for a total of 1000 StreamBlocks
    5. Increase the burst size 65535 X 1000 that will increase the number to 65535000.
  4. NOTE: there is a known limitation for the DX-10G-S32 it works once then fails (ID increments). By taking the port offline and online, it will work once again.
Method 2:
As a second solution, as there is a difference between StreamBlocks created by Spirent TestCenter which are hardware generated and custom StreamBlocks that regard the StreamBlock as data, you can create the StreamBlock you require and transmit a burst that size to transmit and capture using Wireshark.
Create a custom StreamBlock from each in the following manner (instructions how to copy Wireshark packet to TestCenter):
  1. Open trace file: right click on top on the packet, scroll down to Copy ->Bytes (Hex Stream)
  2. Open Spirent TestCenter
    1. Reserve port
    2. Traffic Generator -> Add Raw Stream Block
    3. General – Frame Size Auto
    4. Frame – Create New Frame
      1. Allow Invalid Packets
      2. Data Link Layer - None
      3. Upper Layer Protocol – None
      4. Category – Custom
      5. OK
      6. Custom – Byte Pattern (hex) Paste
      7. General – Signature (perhaps deselect)
      8. OK
      9. Apply
  3. TX and capture to verify

Product : L2-3,Spirent TestCenter,IP,PGA