Data plane protocols and fragmentation for 5G

Abstract

Mobile networks up to this point have used general packet radio service (GPRS) tunneling protocol (GTP) in the core network. The fifth generation (5G) will be a major revolution in mobile networks and there have been discussions onto adopting a different protocol, with the proposals being generic routing encapsulation (GRE), virtual extensible local area network (VXLAN) and generic network virtualization encapsulation (Geneve). In this paper, these protocols are compared. GTP has a 32-bit tunnel endpoint identifier (TEID) and runs on top of user datagram protocol (UDP), thus allowing many applications in the same IP address in different ports. However, GTP unnecessarily stores packet length many times in the Internet protocol (IP), UDP and GTP levels, and the fragmentation strategy defined in third generation partnership project (3GPP) specifications is suboptimal. GRE has well-defined fragmentation strategy but runs directly on top of IP, so multiplexing based on ports is not possible. VXLAN and Geneve have only 24 bits for network identifier and encapsulate media access control (MAC) frames, which is not really what is needed here, and the fragmentation strategy of VXLAN is suboptimal albeit in a different way than in GTP. In this paper, we propose a common fragmentation strategy that may be applicable to all protocols.