Patent ID: 8817820

Claim:
A fragmentation repetition detection apparatus in a multicast environment, comprising: a packet capturing unit that captures a packet transmitted from a server; a fragmentation repetition detector that detects whether or not the captured packet has been repetitively fragmented in more than one router of the multicast environment, and acquires path maximum transmission unit (PMTU) information of the captured packet; and a PMTU transmitter that transmits the PMTU information acquired by the fragmentation repetition detector to the server when the captured packet is a repetitively-fragmented packet, wherein the fragmentation repetition detector performs the detection using information included in an IP header of the captured packet, and the fragmentation repetition detector is configured to check whether or not identification information of the captured packet is previously stored, and when the identification information of the captured packet is not previously stored, to check a flag value and an offset value included in the IP header of the packet to determine whether or not the packet is a first fragmented packet, and when the packet is the first fragmented packet, to record a state of an identification of the captured packet as a first fragmentation state, when the identification information of the captured packet is previously stored, to check whether the state of the identification is the first fragmentation state or a last fragmentation state, and when the state of the identification is the first fragmentation state, to check the flag value included in the IP header of the captured packet to determine whether or not the packet is a last fragmented packet, and when the packet is the last fragmented packet, to record the state of the identification as the last fragmentation state, and when the state of the identification is the last fragmentation state, to check the flag value included in the IP header of the captured packet to determine whether or not the packet is the last fragmented packet, and when the packet is the last fragmented packet, to record the state of the identification as a repetition fragmentation state and storing the PMTU information.