Embodiments of the present invention provide path MTU discovery of a network path, such as an IPv4 network. According to various embodiments of the invention, a node receives a packet at a node along the network path between a source node and a destination node, compares a MTU size of a next hop along the network path with the size of the packet, responsive to the MTU size of the next hop along the network path being less than the size of the packet and responsive to the packet supporting path MTU discovery, the node truncates the packet to the MTU size of the next hop, stores the MTU size in the portion of the packet reserved for PMTU size, and forwards the packet.