Final answer:
Contrail Device Manager uses NETCONF to configure physical routers. NETCONF allows for installation, manipulation, and deletion of network configurations across multiple devices within an SDN setup.
Step-by-step explanation:
The protocol used by Contrail Device Manager to configure physical routers is NETCONF (Network Configuration Protocol). NETCONF provides mechanisms to install, manipulate, and delete the configuration of network devices. It is widely used due to its support for both configuration and state data on the device, error checking, and the ability to roll back configurations to a previous state.
Usually, in the context of Contrail Device Manager, which is part of a Software Defined Networking (SDN) solution, NETCONF is used to automate the configuration of not just one but potentially multiple physical routers, thereby streamlining the management and operation of large-scale networks.