The cross-connect card is the central element for ONS 15454 switching. Available cross-connects are XC, XCVT, and XC10G. The XC establishes connections and performs time division switching (TDS) at the STS-1 level between ONS 15454 traffic cards.The switch matrix on the XC card consists of 288 bi-directional ports. When creating bi-directional STS-1 cross-connects, each cross-connect uses two STS-1 ports. This results in 144 bi-directional STS-1 cross-connects. The switch matrix is fully crosspoint, non-blocking, and broadcast supporting. (Any STS-1 on any port can be connected to any other port, meaning that the STS cross-connections are non-blocking.) This allows network operators to concentrate or groom low-speed traffic from line cards onto high-speed transport spans and to drop low-speed traffic from transport spans onto line cards.The XC card has 12 input ports and 12 output ports. Four input and output ports operate at either STS-12 or STS-48 rates. The remaining eight input and output ports operate at the STS-12 rate. An STS-1 on any of the input ports can be mapped to an STS-1 output port, thus providing full STS-1 time slot assignments (TSA).The XC card works with the TCC+ card to maintain connections and set up cross-connects within the ONS 15454. XC, XCVT, or XC10G is required to operate the ONS 15454. You establish cross-connect and provisioning information through CTC. The TCC+ establishes the proper internal cross-connect information and relays the setup information to the cross-connect card.