Overlay VPNs — DMVPN & FlexVPN

Three generations of Cisco multipoint VPN, all built from the same bricks (mGRE + IPsec + a smart control plane): DMVPN mGRE one interface, infinite spokes; NHRP maps tunnel IPs to real WAN IPs; IPsec encrypts per-tunnel via tunnel protection ipsec profile. Phase 1 hub-and-spoke, phase 2 spoke-to-spoke on demand, phase 3 NHRP redirect/shortcut — […]