Which protocol is used to secure control-plane adjacencies between Cisco SD-WAN nodes?

Cisco SD-WAN uses Transport Layer Security (TLS) to secure control-plane adjacencies between SD-WAN nodes like vSmart controllers, vBond orchestrators, and vEdge/Catalyst Edge devices. TLS provides authentication, integrity, and confidentiality for the communication channels that carry routing information and policies. While IPsec and ESP are crucial for securing the data plane (user traffic) in SD-WAN, they are not primarily used for control-plane adjacency security. IKE (Internet Key Exchange) is used to establish IPsec SAs, but TLS is the direct protocol for securing the control plane itself.