Hello,
It depends on the hardware. If memory serves (and others can correct me):
It is possible on all MX-series and newer T-series linecards.
It is possible with Ethernet IQ/IQ2/IQ2E PICs on M-series.
It is possible on branch SRX in packet mode.
It is NOT possible on older M-series Ethernet PICs (those which don't have IQ/IQ2/IQE in their name).
It is NOT possible on branch SRX in flow mode as in that case "flexible-ethernet-services" knob is only supported for VPLS.
HTH
Thanks
Alex