I was waiting for this feature and it is available from the new version 15.1x49-D70 onwards...
CoS support for the st0 interface for SRX Series devices and vSRX instances—Starting with Junos OS 15.1X49-D70, class of service (CoS) features such as classifier, policer, queuing, scheduling, shaping, rewriting markers, and virtual channels can now be configured on the secure tunnel interface (st0) for point-to-point VPNs.
Best Regards,
Valter
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