In DMVPN (Dynamic Multipoint VPN), when troubleshooting BFD (Bidirectional Forwarding Detection), the NONE (N) state indicates that BFD is missing on a peer or that BFD is not properly configured for the DMVPN tunnel.
BFD is used to detect link failures rapidly and is often implemented in DMVPN to improve convergence times in dynamic networks. If the BFD session is not established, it will remain in the NONE (N) state, signaling that no BFD configuration exists on the peer.