The DSCP value used to represent the internal QoS label (3 bits PHB+2 bits Drop precedence). The MSB 4 bits of DSCP is used to represent PHB value of QoS label; The LSB 2 bits of DSCP are used to represent the drop precedence value of QoS label. Green(0), Yellow(3), Red(1). In a word, PHB=(DSCP>>2), Drop precedence=(DSCP & 0x3). Note: The setting range of PHB value must be 0~7 and the setting drop precedence value must be one of the values (0,1,3).