Thanks for the responses. The initial idea in https://forums.juniper.net/t5/Ethernet-Switching/Interface-storming-for-validation-of-physical-interface/m-p/317706#M17566 was to not use Juniper as a traffic generator, but to instead use the SUT (interfacing with Juniper) to start an L2 storm and run a storm between Juniper and the SUT for some standardized packet count.
I'm investigating the idea of changing roles and having Juniper start the storm between the SUT and Juniper.
RFC 2544 testing may do the trick, let me investigate a bit more. Thanks,