US Patent 8121135 Discovering path maximum transmission unit size

Intermediate network devices, such as routers, are configured to discover a maximum transmission unit (MTU) for a path between two network endpoints by removing data from packets when the packet size exceeds a link MTU to a next hop. An example intermediate network device includes a forwarding engine to determine an interface card through which to forward a received packet and to determine a link MTU for a link corresponding to the interface card, wherein the received packet comprises a header and a payload, the header indicating not to fragment the packet, and a PMTU determination module to determine whether a size of the received packet exceeds the link MTU, and to remove a portion of data from the payload of the packet, discard the removed portion, and adjust the header of the packet according to the removed portion when the size of the received packet exceeds the link MTU.