Migration plan: Traditional Wan to SD-WAN:

https://www.velocloud.com/sd-wan-resources/webinars/migrate-from-traditional-wan-to-sd-wan

"Gold Site": Dual L3 SW, MPLS + Internet

Silver Site 1: Single L3 switch, 

Centralized Controller:   Routing Control:  Reflect the route to Edge ( like RR ) 

No router inside the tunnel >>> centralized 

1- single pan of glass , centralize Policy

2- 

Why Block S1,S2 and S3 and not lower the Local Preference ?

In case we loose Internet Link.

>>> Solution: Advertise with a summarized route ( Vs a more specific route )