When creating a Cloud VPN, there are three routing options you can choose:
- Dynamic routing with BGP
- Policy based
- Route based
The policy and route based options both use static routing, while dynamic routing is based on the Border Gateway routing Protocol (BGP).
Dynamic routing is the preferred method if the on-premises VPN gateway supports BGP. This option can also be used to connect two Cloud VPN gateways together. Dynamic routing supports route advertisement as well as the ability to add and remove routes without having to rebuild a VPN tunnel.
With the policy based option, local IP ranges (left side) and remote IP ranges (right side) are specified and used as the traffic selectors for the VPN tunnel.
Route based VPN specifies only the remote IP ranges (right side). The list of local IP ranges is assumed to be any network (0.0.0.0).