Using ELSM with Layer 2 Control Protocols
You can use ELSM with Layer 2 control protocols such as STP, ESRP, EAPS, and so on to improve the recovery of Layer 2 loops in the network.
ELSM detects remote link failures if the established link is through a Layer 2 transport cloud and the ELSM endpoints traverse the Layer 2 cloud in a point-to-point fashion, as shown in ELSM Through a Layer 2 Cloud.
A sudden failure of the switch CPU may cause the hardware to continue forwarding traffic. For example, ESRP may select a second device for forwarding traffic thereby creating a Layer 2 loop in the network. If you configure ELSM and the CPU fails, ELSM closes the connection to the faulty device to prevent a loop.