The ITU-T G.8032 protocol only defines the automatic protection scheme for Ethernet ring networks when a single link fails

but not when multistage links fail.This paper expounds the working principle of the single ring and multiple rings in the ITU-T G.8032 and analyzes the problems and defects in multiple rings.On this basis

it presents a multistage protection switching mechanism for multiple rings.Using the concept of virtual links in multiple rings

it focuses on the research on the failure detection and the virtual link protection

thus realizing the protection of the multi-stage rings in Ethernet ring networks.The test results show that the multistage protection switching can be accomplished within 50 ms

satisfying the self-healing time requirement of the carrier-class Ethernet networks and improving their reliability.