Patent ID: 7765357

Claim:
A PCI-Express communication system, which uses a PCI-Express switch carrying out packet transfer by connecting a plurality of modules, comprising: setting a unique node ID for each of a plurality of the modules for indicating each module, as well as setting a channel ID for each channel used for data transfer, the channel used for the data transfer being provided with a PUT transfer dedicated channel for writing data in a module at another end and a GET transfer dedicated channel for reading data from a module at another end; setting in an address field of a packet for data transfer, the node ID of a transfer destination module, the channel ID of the channel used for the data transfer, a packet type to indicate whether the packet is a request or a response type packet, and a sequence code indicating the sequence number of a packet in a series of packet transfers, the transfer destination module checking whether the packet is received in a correct order or not based on the sequence code; and using a memory write request packet to be routed according to a PCI-Express switch address routing for the data transfer, wherein when replying with a response packet in response to the packet received by the transfer destination module, a sequence code that is the same as the sequence code of the received packet is set in the response packet, a reply destination module of the response packet checks whether the response packet was transferred in the correct order based on the sequence code, and when receiving the request packet, if the series of packets are being transferred, whether the series of packets are received in the correct order or not is checked based on the sequence code, and if the series of packets are not received in the correct order, a status code indicating error contents is set to the response packet.