The 4-port Gigabit Ethernet Layer 3 Switching Module for the CoreBuilder 9000 Enterprise Switch and Switch 4007 provides high-port-density, line speed, Gigabit Ethernet switching and routing on backbone networks running at Open Systems Interconnection (OSI) Layer 3. The module offers the following connectivity: - Four Gigabit Interface Converter (GBIC) ports on the front panel can be either 1000BASE-LX (single-mode fiber) or 1000BASE-SX (multimode fiber). Four Gigabit Ethernet ports connect the module to the chassis backplane. The 4-port Gigabit Ethernet Layer 3 Switching Module supports the following key features: High-density Gigabit Ethernet switching through the following maximum number of GBIC front panel ports: 24 ports in the 7-slot and 8-slot chassis. 56 ports in the 16-slot chassis. Ability to use multi-mode and single-mode 1000BASE-LX GBICs and multi-mode 1000BASE-SX GBICs simultaneously on the front panel. Ability to replace the module and GBIC ports while the chassis is operating. GBIC Transceivers each sold separatel.