The present disclosure discloses a method, system, and device for forwarding data frames, and relates to the communication field. The method includes: An upstream near-end device in a faulty part of a working tunnel activates a segmental protection tunnel after receiving a data frame when a part of the working tunnel fails, where the start node of the segmental protection tunnel is the upstream near-end device and the end node of the segmental protection tunnel is a downstream near-end device in the faulty part; the upstream near-end device forwards the data frame to the downstream near-end device through the segmental protection tunnel; and the data frame at the downstream near-end device is forwarded to the destination device through the faultless part of the working tunnel. The present disclosure provides segmental protection for the PBB TE tunnel.