This document discusses several VPN technologies including:
1. Naked DMVPN which allows direct spoke-to-spoke tunnels without traversing the hub to lower costs and increase bandwidth.
2. Protected DMVPN which adds IPsec encryption to DMVPN tunnels for added security using ISAKMP/IKE and crypto profiles.
3. IKE call admission control which discusses IKEv1 and IKEv2 protocols used to set up IPsec security associations and their differences like improved NAT traversal and liveness detection in IKEv2.