The Cisco WS-X6904-40G-2T is a line card module for Cisco Catalyst 6500 Series switches. It is designed to provide high-performance, high-density 40 Gigabit Ethernet (40G) and 10 Gigabit Ethernet (10G) connectivity for data centers and enterprise networks. The WS-X6904-40G-2T features four 40G ports and two 10G ports, allowing for flexible connectivity options. It supports various network protocols and features, including Layer 2 and Layer 3 forwarding, IPv4 and IPv6 routing, Quality of Service (QoS), and security features. This line card module is hot-swappable, meaning it can be inserted or removed from the switch without disrupting network operations. It is compatible with Cisco Catalyst 6500 Series switches that support the Supervisor Engine 2T or Supervisor Engine 2TXL. Overall, the Cisco WS-X6904-40G-2T provides high-speed and high-density connectivity options for organizations that require advanced networking capabilities.