Vehicular Delay-Tolerant Networks (VDTNs) is a breakthrough based DTN-based solution to provide vehicular communications under challenging scenarios characterized by long delays and sporadic connections. VDTN uses a store-carry-and-forward paradigm, inspirited from Delay Tolerant Networks, which allows forward bundles to asynchronously reach the destination hop by hop over traveling vehicles equipped with short-range Wi-Fi devices. The proposed VDTN architecture assumes out-of-band signaling with control and data planes separation. VDTNs also assume datagrams aggregation under the network layer in large size packets, called bundles, following an IP over VDTN approach. This paper presents VDTN networks focusing on their layered architecture, bundle aggregation and de-aggregation mechanisms, network protocols, scheduling and dropping policies, fragmentation mechanisms, and the created tools for VDTNs performance evaluation, demonstration, and validation.