The value is to remark When red action is remarking.
For remarking DSCP, the range is 0~63;
For remarking IP Precedence and MPLS EXP, the range is 0~7;
Only software QoS support this node.
-1 is returned only when getting value from hardware QoS or
when action being pass, discard of software QoS.
-1 can't be set.