d QoS; and establishment of IPsec security association (IPsec SA) to support PDU session traffic. UPF acts as the anchor point for intra-RAT or inter-RAT mobility; external PDU ses- sion point of interconnect to the data network; packet routing and forwarding; packet inspection and user-plane part of policy rule enforcement; lawful interception; traffic usage reporting; uplink classifier to support routing traffic flows to a data network; branching point to support multi-homed PDU session; QoS handling for user plane (packet filtering, gating, and UL/DL rate enforcement); uplink traffic verification (SDF to QoS flow mapping); transport-level packet marking in the uplink and downlink; and downlink packet buffering and downlink data notification triggering. AF is responsible for interacting with the 3GPP core network in order to support appli- cation influence on traffic routing; accessing network exposure function; and interacting with the policy framework for policy control. Based on operator deployment, the AF is considered to be trusted by the operator and can be allowed to interact directly with rel- evant NFs. IKE or IKEv2 is the protocol used to set up a security association in the IPsec protocol suite. The IKE proto- col is based on a key-agreement protocol and the Internet security association and key management protocol which is a protocol defined by IETF RFC 2408 for establishing security associations and cryptographic keys in an Internet environment. The IKE uses X.509 certificates for authentication which are either pre-shared or distributed to set up a shared session secret from which cryptographic keys are derived. In addition, a secu- rity policy for every peer which will connect must be manually maintained. IPsec is a set of protocols for securing IP-based communications by authenticating and encrypting each IP packet of a data stream. IPsec also includes protocols for establishing mutual authentication between agents at the beginning of the session and negotiation of cryptographic keys to be used 