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Spirent TestCenter: Why does the APPLY fails for a certain number of stream blocks but it works for a larger one?

  • Spirent TestCenter.
  • PX3 Yellowstone cards.
The PX3 Yellowstone 100G default performance mode supports a maximum of 64 paths.  When the configured path is <= 64 (such as t400 streams, 40 paths configuration), the BLL will send this configuration directly to the IL; during the IL check it notices it exceeds the maximum allowed memory of the FPGA, then an error will show up and apply will fail..

If the configured path is > 64 (such as 1000 streams, 1000 paths configuration), the BLL will do a path compression first and then send the compressed streams with VFD/RIT modifiers to the IL, after the path compression, the streams configurations happened not to exceed the maximum allowed memory of the FPGA, so apply will succeed with no errors.

One workaround for the 400 streams configuration is to set the port at 100G Performance mode, this mode has better performance (supports max 256 paths) than the 100G Default mode so, the apply should succeed in 100G perf mode.
NOTE: Different type of modules may have different FPGA memory and max supported paths, some modules supports IL based path compression , some modules do not support IL based path compression, then they will use the BLL based path compression. The path compression is managed by the BLL or IL automatically, the user cannot control it.


Product : PX3,Spirent TestCenter