Cisco Viptela SDWAN: OMP Best Path Algorithm & Loop Avoidance

Today I am going to discuss about the overlay routing protocol used in Cisco Viptela SDWAN solution. The name of the routing protocol is OMP. As most of you already knows about the OMP protocol, how it works and the purpose of the OMP protocol. 

In this article I am going to talk about the OMP best Path selection criteria and how it avoids loop in the WAN Fabric network.

Well before talking about the best oath selection, Lets have a quick words on OMP protocol. OMP learns and translates routing information across the overlay in the form of OMP routes, TLOC routes, network service routes.

Apart from it OMP also have Unicast and Multicast address families with IPv4 support. 

OMP also distribute of data-plane security parameters and implementation of control and VPN membership policies.

Fig 1.1- OMP Protocol in Cisco Viptela SDWAN

Below is the OMP best Path selection criteria 
  1. Next hop TLOC is reachable
  2. Prefer Edge-sourced route over vSmart-sourced route
  3. Prefer OMP route with lower admin distance
  4. Prefer OMP route with higher route preference
  5. Prefer OMP route with higher TLOC preference
  6. Prefer highest origin (Connected, Static, OSPF Intra, OSPF Inter, OSPF External. iBGP, Unknown/Unset)
  7. Prefer route from higher Router-ID (System-IP)
  8. Prefer highest TLOC private IP address
Note below points:
  1. vSmart will advertised 4 ECMP paths by default and it can go maximum to 16 paths.
  2. vSmart can send backup path for faster reroute on WAN Edge.