202 the splitter 240 splits an optical signal having a transmission speed a in a downstream direction and transmits the split optical signals to the onts 220 through 230 k denotes the number of branches of the splitter 240 the splitter 240 multiplexes optical signals received from the onts 220 through 230 in a upstream direction and transmits the multiplexed optical signals to the optical transceivers 204 and 206 of the olt 200 the onts 220 through 230 respectively include optical transceivers 221 and 231 tdma pon mac processors 222 and 232 and bridges 223 and 233 the optical transceivers 221 and 231 convert optical signals into electric signals and transmit the electric signals to the tdma pon mac processors 222 and 232 the optical transceivers 204 and 206 convert electric signals into optical signals in a upstream direction transmit the optical signals only when a transmission of frames is allowed and intercepts the optical signals so as to prevent signal interference among the onts 220 through 230 the tdma pon mac processors 222 and 232 recover tdma pon frames received from the olt 200 in a downstream direction convert only tdma pon frames transmitted the tdma pon mac processors 222 and 232 into ethernet frames and transmit the ethernet frames to the bridges 223 and 233 the tdma pon mac.