Patent ID: 8243736

Claim:
A packet capturing device comprising: an acquisition unit that acquires an identifier (ID) value and a sequence number written on a header of a received packet; a storage unit that stores a previous ID value which is an ID value of a previously-received packet and a next sequence number which is a sequence number that a next packet to be received should have; and a detection unit that judges whether a delay of the received packet is caused by a simple delay or a retransmission accompanying a loss, wherein the detection unit compares the next sequence number with a sequence number of the received packet, compares the previous ID value with an ID value of the received packet, and judges that the delay is a simple delay when the next sequence number matches the sequence number of the received packet and the previous ID value is followed by the ID value of the received packet and judges that the delay is caused by a retransmission when the previous ID value is not followed by the ID value of the received packet.