Patent ID: 7978681

Claim:
A network apparatus for discovering a path maximum transmission unit (MTU) in a data communication network, comprising: a MTU-comparer detecting a path MTU recorded on a predetermined packet transferred over a routing path between a source node and a destination node and comparing the detected path MTU with an internal MTU stored in the MTU-comparer; and an event-processor updating the path MTU recorded on the predetermined packet to contain the internal MTU if the detected path MTU is larger than the internal MTU, wherein an extension header of the predetermined packet with the path MTU recorded thereon comprises: a type field representing whether a new path MTU is detected; and a path MTU storage field, which is initialized to a null value by at least one of the source node and the destination node, storing the new path MTU therein to update a path MTU in the path MTU storage field when the new path MTU is detected, and wherein the predetermined packet comprises at least one of a data packet and a binding update message packet, wherein the routing path between the source node and the destination node comprises at least one intermediate node, one intermediate node which has received the predetermined packet updates the path MTU in the received predetermined packet if the path MTU in the received predetermined packet is larger than the internal MTU on the one intermediate node and forwards the received predetermined packet to next intermediate node or the destination node.