a UE to map uplink user-plane traffic to QoS flows without SMF provided QoS rules, which is applied to IP and Ethernet PDU sessions. The support of reflective QoS over the access network is controlled by 5GC. The UE derives the reflective QoS rule from the received downlink traffic. It must be noted that it is possible to apply reflective QoS and non-reflective QoS concurrently within the same PDU session. For user traffic that is subject to reflective QoS, the uplink packets are assigned the same QoS mark- ing as the reflected downlink packets. Reflective QoS is controlled on per-packet basis using the RQI in the encapsulation header on N3 reference point together with the QFI and a reflective QoS timer (RQ timer) value that is either signaled to the UE upon PDU session establishment or set to a default value. To summarize this section, as we discussed 5G session management supports a PDU con- nectivity service that provides PDU exchange between a UE and a data network. In 5GC, the SMF is responsible for handling session management procedures. There is a notable difference in session management between EPC and 5GC. In EPC, the entire ses- sion is maintained by a single MME in a centralized manner, SO that the user-plane path is established via a centralized PGW. This potentially results in congestion of backhaul traffic at the PGW, whereas in 5GC, different PDU sessions can be maintained by conceivably dif- ferent SMFs, and their user-plane paths are established via multiple UPFs. This can distrib- ute the cellular operator's backhaul traffic within the 5GC and reduce the perceived latency by the user. Compared to LTE's QoS framework, which is bearer-based and uses control- plane signaling, the 5G system adopts the QoS flow-based framework, and uses both control-plane and user-plane (i.e., reflective QoS) signaling in order to satisfy various appli- cation/service QoS requirements. The QoS flow-based framework enables flexible mapping of QoS flows to DRB(s) by decoupling the QoS flow and the radio bearer, allowi