Patent ID: 8112517
Filing Date: 2012-02-07
Classification: H04L

Abstract:
1. A relay system for relaying first communication data between a client device and a host device, and second communication data between the host device and a third device different from the client device in response to a request from the client device in the first communication data, the relay system comprising; a storage unit; and a controller; wherein the controller performs processing of: monitoring the second communication data, acquiring, from the storage unit, a priority associated with a respective protocol in the second communication data, setting the priority, as a priority of communication data that is returned to the client device from the host device in the first communication data, and transmitting the communication data to the client device as a destination, wherein the storage unit comprises: an inward coupling management table for storing information to specify the first communication data; an outward coupling management table for storing information to specify the second communication data; and a service priority definition table for storing the priority associated with the protocol used in the second communication data; wherein, the inward coupling management table comprises a coupling source field, a coupling destination field, and an entry validity period field; wherein, the controller further performs processing of: determining, upon receipt of communication data, whether the communication data is the first communication data based on source IP address, destination IP address, source port number and destination port number thereof, if the communication data is the first communication data, generating a new entry in the inward coupling management table, storing an IP address and a port number of the client device as a coupling source in the IP address field and the port number field of the coupling source field of the entry, storing an IP address and a port number of the host device as a coupling destination in the IP address field and the port number field of the coupling destination field of the entry, and storing a value to specify a predetermined validity period in the entry validity period field of the entry, if communication data is not the first communication data, determining whether the communication data is the second communication data based on source IP address, destination IP address, source port number and destination port number thereof, if the communication data is the second communication data from the host device to the third device, generating a new entry in the outward coupling management table, storing a source IP address and a source port number of the communication data in the IP address field and the port number field of the coupling source field of the entry, storing a destination IP address and a destination port number of the communication data in the IP address field and the port number field of the coupling destination field of the entry, storing values to specify a predetermined validity period in the entry validity period field of the entry, searching the service priority definition table by using a destination port number of the communication data as a search key, storing a value stored in the delivery priority field of the matched entry to the delivery priority field of the entry in the outward coupling management table, and if the communication data is the first communication data from the host device to the client device, changing a priority of the communication data to a priority specified by the value.