High-priority queue on SPC

Use this option to enable packets with specific Differentiated Services (DiffServ) code points (DSCP) precedence bits to enter a high-priority queue on the Services Processing Card (SPC) on high-end SRX Series devices. The Services Processing Unit (SPU) draws packets from the high-priority queue and only draws packets from the low-priority queue when the high-priority queue is empty. This feature can reduce overall latency for real-time traffic, such as voice traffic.