Abstract: Example methods are provided for a network device to perform path maximum transmission unit discovery (PMTU) in a software-defined networking (SDN) environment. One example method may comprise detecting an egress packet that includes an inner header. The method may also comprise: in response to determination that a first maximum transmission unit (MTU) associated with a path between the first node and the second node is exceeded by a total size of the egress packet and an encapsulation overhead, generating an error packet that specifies a second MTU that is configured to be less than the first MTU based on the encapsulation overhead. The error packet may be sent to the first node to cause the first node to size a subsequent egress packet to the second inner address based on the second MTU.