Futurewei Telefonica Altiostar Apstra, Inc. Nokia This document describes few 5G mobility scenarios and how mobile network functions map its SST criteria to identifiers in IP packets that transport segments use to grant transport layer services. This is based on mapping between mobile and IP transport underlays (IPv6, MPLS, IPv4) and a new transport network underlay routing mechanism, Preferred Path Routing (PPR), which brings slice properties and works with any underlying transport (L2, IPv4, SR and MPLS) is described.