Fault detection technologies are classified as special detection technologies or common detection technologies by usage scope.
ETH OAM, which applies to the data link layer
Common fault detection technologies include Bidirectional Forwarding Detection (BFD), which applies to all layers.
Each layer of the TCP/IP reference model has fault detection mechanisms:
Data link layer: ETH OAM, Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP), MSTP
Network layer: Hello mechanism provided by protocols, Virtual Router Redundancy Protocol (VRRP), and graceful restart (GR)
Application layer: heartbeat and retransmission mechanisms provided by protocols
Fault detection modes include:
Asynchronous mode: Probe packets are sent periodically.
Echo mode: Received packets are sent back to a peer without any change.