At the heart of the Cisco 12000 GSR is a multigigabit crossbar switch fabric that is optimized to provide high-capacity switching at gigabit rates. The crossbar switch enables high performance for two reasons: connections from the LCs to a centralized fabric are point-to-point links that can operate at very high speeds and multiple bus transactions can be supported simultaneously, increasing the aggregate bandwidth of the system. A GSR system can be configured as 40 Gbps for the Cisco 12008, 60 Gbps for the Cisco 120012, and 80 Gbps for the Cisco 12016.