The Cisco XR 12000/12000 SIP-600 is a modular high-speed 10-Gbps SIP based on IP Services Engine (ISE) technology. The Cisco XR 12000/12000 SIP-600 hosts the common SPAs used for interconnecting routers with each other or with other networking devices such as Web servers, storage devices, and ATM or Ethernet switches. The Cisco XR 12000/12000 SIP-600 enhances and scales all functions and services previously available on the 2.5-Gbps ISE line card. Examples of these enhancements include line-rate IPv6 at 10 Gbps, scalable multicast and native multicast quality of service (QoS), and thousands of user interfaces, each dynamically associated with one or multiple class-of-service (CoS) queues.