A system and method for switching packet traffic over an optical transport network comprises a network element having first and second mappers for mapping packet traffic to electrical streams. A network interface includes a packet switch that directs a first packet stream to the first mapper based on a destination of the packets in the first packet stream and a second packet stream to the second mapper based on a destination of the packets in the second packet stream. The first mapper produces a first stream of electrical signals from the first packet stream, and the second mapper produces a second stream of electrical signals from the second packet stream. Each electrical signal stream is allocated a portion of bandwidth of an optical interface. The optical interface produces an optical signal that includes the first and second electrical signal streams according to the bandwidth allocated to each electrical signal stream.