Field Trial of Telecom-Grade Sub-50ms Protection in Wave-Length Switched Optical Networks for Lossless Large Language Model Multi-Datacenter Distributed Training. - Yuyang Liu; Anxu Zhang; Kai Lv; Xishuo Wang; Lipeng Feng; Hao Liu; Xia Sheng; Cong Li; Siwei Ji; Tao Ma; Tianhai Chang; Qingcong Lu; et al. (ECOC, 2025)