Administrative Distance values in Cisco Viptela SDWAN

Today I am going to talk about the AD values used in the Cisco Viptela SDWAN solution. Although you guys know about the values in general used in the Cisco devices for path selection.

What is Administrative Distance (AD)
In simple words if we have two or more paths to the same destination, we will select the best path between these paths and is based on the Administrative Distance. 

Higher the value less preferred path for AD to select as traffic flow. In Cisco Viptela SDWAN solution, when the vSmart controller or vEdge/cEdge is selecting the OMP route to a destination, it prefers the path with the lowest administrative distance value. 

Fig 1.1- Cisco SDWAN Viptela Connectivity

In the Cisco Viptela SDWAN environment, below are the values used for protocol as AD values

1. Connected : 0 (AD Value)
2. Static : 1 (AD Value)
3. NAT : 1 (AD Value)
4. Learned from DHCP : 1 (AD Value)
5. GRE : 5 (AD Value)
6. eBGP: 20 (AD Value)
7. OSPF: 110 (AD Value)
8. iBGP: 200 (AD Value)
9. OMP: 250 (AD Value)

Note: NAT and Static route cannot exists in the same VPN. NAT always overwrites static route.