Abstract: A packet processing method executed by a system including a first apparatus and a second apparatus, the first apparatus having a first processor and a plurality of interfaces and a second apparatus having a second processor and a plurality of third processors, the packet processing method includes receiving, by the first processor, a packet via an interface in the plurality of interfaces; storing identification information of the interface into the packet; transmitting the packet to the second apparatus; receiving, by the second processor, the packet transmitted from the first apparatus; selecting a processor from the plurality of third processors based on the identification information included in the received packet; and executing processing of the packet using the selected processor.

Abstract: A communication state between a session initiation protocol server and another session initiation protocol server to be a destination for transmitting a request message is determined. When it is determined that the communication state is in a communication unavailable state, a subsequent session initiation protocol server of the session initiation protocol server designated as the destination is determined to be a new destination based on information on a relay order of the session initiation protocol servers set in header information of the request message.