Patent ID: 7447429

Claim:
A bidirectional line switched ring network in a synchronous optical network (SONET) comprising: a plurality of optical transmission equipment sets connected in a ring form via high speed bidirectional channels of a synchronous transport signal (STS) level, wherein lower order channels of a virtual tributary (VT) level are mapped on the high speed bidirectional channels, optical transmission equipment provided in a node on the transmission side performs transmission to each lower-order channel by attaching a transmission-side node ID, and, optical transmission equipment provided in a node on the reception side collates the received transmission-side node ID, which is transmitted using a V3 byte of a virtual tributary (VT) super frame on which each of the lower-order channels of the VT level is mapped, with an expected value of the transmission-side node ID having been set in advance, and when the collation does not match, the optical transmission equipment in the node on the reception side prevents a misconnection in the event of a failure by inserting an alarm indication signal, wherein, using the V3 bytes for three frames, in addition to the transmission-side node ID, a channel ID is additionally transmitted to each lower order channel, so that the time slot interchange (TSI) of the lower-order channel is enabled in a pass-through node.