An interworking device, method and system distribute reference timing between at least two communication networks. The interworking device includes a first
communication interface operable to communicate with a first communication network operating using a first communication protocol and a second
communication interface operable to communicate with a second communication network operating using a second communication protocol. The interworking device also includes a
client generic framing procedure /
optical transport network (“GFP / OTN”) mapping block in communication with the first
communication interface and the second communication interface. The
client GFP / OTN mapping block recovers a first reference timing
signal from data received from the first communication network. At least one
hybrid synchronous equipment timing source transforms the first reference timing
signal into a second reference timing
signal that is phase and frequency locked to the first reference timing signal, and supplies the second reference timing signal to the
client GFP / OTN mapping block to
clock the second communication network.