The Parallels provider supports all networking features described in the Vagrant Networking documentation.
By default, the Parallels provider automatically configures your virtual machine network adapter to the Shared networking type. In order to access the Vagrant environment created, the Parallels provider uses an IP address, which the virtual machine leased from the internal DHCP-server.
You don't need to add any heuristic configuration in the Vagrantfile to use basic communications with your virtual environment.
Starting with Parallels Desktop 10 for Mac it is also possible to configure port forwarding between the guest virtual machine and your Mac host.