The Cisco XR 12000 and 12000 Series 4-Port Gigabit Ethernet ISE Line Card (4-port GE ISE card) delivers a comprehensive range of features at line rate that help enable many Layer 2 and Layer 3 Ethernet edge applications such as Metro Ethernet aggregation, peering, and Cisco IPv6 services without compromising performance. The line card provides granular quality of service (QoS) with dedicated queues per VLAN. Each card supports 4 physical ports and 1020 VLANs, and 4 classes of service can be provided in each VLAN or port.The card has been designed to be highly flexible to accommodate the new features required by service providers. Supported by the Cisco XR 12000 and 12000 series distributed system architecture, the Cisco 4-port GE ISE line card provides advanced features, and it maintains performance when the features are enabled as a result of the dedicated Layer 3 forwarding application-specific-integrated-circuit (ASIC) and advanced-memory components. Card features include industry-leading QoS, which is ideal for customer service-level agreements (SLAs); packet filtering and Reverse Path Forwarding (RPF); rate limiting to help ensure that all customers are served according to the SLAs; a comprehensive set of Multiprotocol Label Switching (MPLS) features for high-level services to customers; and Ethernet features such as VLANs, source and destination MAC accounting, and jumbo frames.