Timing Transparent Transcoding (TTT) is used to adapt
a Gigabit Ethernet signal to the
data rate of the Optical Data UnitODU-0.This data rate adaptation is necessary because the payload data rate of ODU-0 with 1.244 Gbit/s
isnot sufficient for the transmission of Gigabit Ethernet
with 1 Gbit/s. The actualdata rate of Gigabit Ethernet
due to the 8B/10B coding used by the Physical Coding Sublayer (PCS) of Gigabit Ethernet. Theactual data rate of Gigabit Ethernet is 1.25 Gbit/s due to the 8B/10B coding
used by the Physical Coding Sublayer
(PCS) of Gigabit Ethernet, which is higher than the supported data rate of the payload signal. The TTT signal is at the input of the optical transport network and reduces the transmitted bit rate with a transparent mapping mechanism, but the information to recover the PCS signal is retained at the output of the optical transport network.