What is Layers 4-7?
Layers 4 through 7 of the OSI model comprise the Transport (Layer 4), Session (Layer 5), Presentation (Layer 6), and Application (Layer 7) layers. These upper layers handle end-to-end data delivery, session management, data formatting, and application-level protocols. In the context of 5G networks, these layers include TCP/UDP transport, TLS encryption, HTTP/2 and HTTP/3 application protocols, and the service-based interfaces used in the 5G Core (SBA) which communicate via RESTful APIs over HTTP/2.
How Does Layers 4-7 Work?
Layer 4 (Transport) manages end-to-end communication using TCP (reliable, connection-oriented) or UDP (lightweight, connectionless). In 5G, GTP-U (GPRS Tunnelling Protocol — User plane) runs over UDP for encapsulating user data between RAN and core network nodes. Layer 5 (Session) manages dialogue control between applications. Layer 6 (Presentation) handles data encoding and encryption. Layer 7 (Application) provides the interface to user applications. In the 5G SBA core, Network Functions communicate via HTTP/2-based APIs — for example, the AMF calls the SMF via a RESTful API to create a session, and the SMF calls the UPF via PFCP (a Layer 4 protocol) to establish user plane rules.
Use Cases
5G Core SBA implementation using HTTP/2 APIs, application layer optimization for eMBB, end-to-end security implementation (TLS 1.3), content delivery and application awareness, and network function service discovery and communication.
3GPP / Standards Reference
3GPP TS 29.500 (5GC service-based interfaces — HTTP/2), 3GPP TS 29.281 (GTP-U), IETF RFCs for TCP, UDP, HTTP/2, TLS
Related Terms
Layer 1 | Layers 2/3 | SBA | Core Network | AMF
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This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
