QoS marking refers to the Type of Service field in IPv4 header or the Traffic Class field in the IPv6 header.
behavior in the private to the public direction
If dscp dscp-name is configured under the IP tunnel, the configured value is used for the QoS marking in the GRE IP header. If DSCP is not configured, then the payload packet’s QoS marking is copied into the GRE IP header.
behavior in the public to private direction
The received ESP packet is decrypted, and as a result, the GRE packet is decapsulated into a payload packet. The QoS marking of the original payload packet is preserved.