(GigaBit Interface Converter) A hardware module used to attach network devices to fiber-based transmission systems such as Fibre Channel and Gigabit Ethernet. The GBIC converts the serial electrical signals to serial optical signals and vice versa. GBIC modules are hot swappable and contain ID and system information that a switch can use to determine the device's capabilities. As a plug-in module, the GBIC enables networking devices to be upgraded in the field to support optical signals.