Fat Pipes for User Plane Tunneling in 5G

The main service of current mobile networks is to transport user data packets between the user devices and external packet data networks. This is done by using transport tunnels which in todays networks are based on the GPRS Tunneling Protocol User Plane (GTP-U) or the Generic Routing Encapsulation (GRE) protocol. These user plane tunnels are denoted as "thin pipes" as they carry only the data of a single user data flow. The tunnels must be setup each time when a UE enters the active mode or starts a session with new service requirements. This is very inefficient especially when a UE transmits small amounts of data only sporadically which is the case e.g. for Machine Type Communication. In contrast to these thin pipes, "fat pipes" using Ethernet over GRE (EoGRE) tunneling can carry the data flows of different users with similar service requirements in the same tunnel. The advantage is that with fat pipes, the amount of control signaling is strongly reduced because the setup and maintenance of user specific tunnels (thin pipes) is avoided. As a second advantage, the Ethernet layer natively supports the transport of IP- as well as of non-IP data. Therefore, this paper proposes to use EoGRE based fat pipes on all network internal interfaces carrying user plane traffic. To enable this solution, this paper further proposes a mapping mechanism of 3GPP based identifiers like temporary mobile subscriber identities to IEEE 802 MAC addresses so that existing Ethernet based mechanisms for the bridging and routing of user plane data can be used. This mapping mechanism also includes a so-called "Network Interface ID in order to support Multi-Connectivity.