The protocol that runs between the vSmart controllers and between the vSmart controllers and the vEdge routers, and unifies all control plane functions under a single protocol umbrella is the Overlay Management Protocol (OMP)12. OMP is a proprietary protocol that is designed to enable the Cisco SD-WAN solution, which provides a software overlay that runs over standard network transport, including MPLS, broadband, and internet to deliver applications and services3. OMP provides the following services12:

Orchestration of overlay network communication, including connectivity among network sites, service chaining, and VPN or VRF topologies

Distribution of service-level routing information and related location mappings

Distribution of data plane security parameters

Central control and distribution of routing policy

OMP is an all-encompassing information management and distribution protocol that enables the overlay network by separating services from transport. Services provided in a typical VPN setting are usually located within a VPN domain, and they are protected so that they are not visible outside the VPN. In such a traditional architecture, it is a challenge to extend VPN domains and service connectivity. OMP addresses these scalability challenges by providing an efficient way to manage service traffic based on the location of logical transport end points. This method extends the data plane and control plane separation concept from within routers to across the network2.

References:

1: Routing Configuration Guide for vEdge Routers, Cisco SD-WAN Release 20.x - Unicast Overlay Routing 2: Introduction to Overlay Management Protocol in Viptela 3: Cisco SD-WAN vEdge vManage vSmart IBM