  Network softwarization triggered a new wave of innovation in modern network
design. The next generation of mobile networks embraces this trend. Mobile-edge
computing (MEC) is a key part of emerging mobile networks that enables
ultra-low latency mission-critical application such as vehicle-to vehicle
communication. MEC aims at bringing delay-sensitive applications closer to the
radio access network to enable ultra-low latency for users and decrease the
back-haul pressure on mobile service providers. However, there are no practical
solutions to enable mobility at MEC where connections are no longer anchored to
the core network and serving applications are supposed to move as their users
move. We propose the mobile-edge gateway (MEGW) to address this gap. MEGW
enables mobility for MEC applications transparently and without requiring any
modifications to existing protocols and applications. MEGW supports mobility by
reconstructing mobile users' location via listening to LTE control plane in
addition to using two-stage location-dependent traffic steering for edge
connections. Networks can incrementally upgrade to support MEC by upgrading
some IP router to programmable switches that run MEGW. We have implemented MEGW
using P4 language and verified its compatibility with existing LTE networks in
a testbed running reference LTE protocol stack. Furthermore, using packet-level
simulations we show that the two-stage traffic steering algorithm reduces the
number of application migrations and simplifies service provisioning.
