This Cisco XR 12000 and 12000 series SPA Interface Processor 601 provides a common forwarding and queuing engine responsible for packet classification, forwarding decisions, packet queuing, and accounting without compromising the performance. It has two forwarding engines, one for ingress and one for egress, allowing the user to implement multiple features and QoS policies at the incoming traffic, independently from the features and the QoS policies applied at the egress interfaces. The multicast replication is done by the egress forwarding engine, hence a very scalable multicast implementation with a native and built-in security and QoS features for multicast flows.