Glossary

Plain-language definitions of the 5G and 3GPP acronyms used across these docs, oriented to dflux TinyCore.

5G is dense with acronyms. This glossary covers the terms that appear throughout the dflux TinyCore documentation, with short definitions geared to how each one shows up in a lab core. Network functions and dflux TinyCore's own component names appear alongside the standard 3GPP terms.

Network functions

Term	Definition
`NF`	Network Function — any of the logical components that make up the 5G core (AMF, SMF, UPF, …).
`AMF`	Access and Mobility Management Function — terminates N1 (NAS) and N2 (NGAP); handles registration and connection management. Lives inside the DMF.
`SMF`	Session Management Function — manages PDU sessions and controls the UPF over N4. Lives inside the DMF.
`AUSF`	Authentication Server Function — runs 5G-AKA / EAP-AKA' authentication. Lives inside the DPF.
`UDM`	Unified Data Management — exposes subscription data and generates authentication vectors. Lives inside the DPF.
`UDR`	Unified Data Repository — the backing store for subscriber and policy data behind the UDM/PCF. Lives inside the DPF.
`PCF`	Policy Control Function — supplies access-mobility and session-management policy. Lives inside the DPF.
`NRF`	Network Repository Function — the service registry where NFs register and discover each other.
`UPF`	User Plane Function — forwards user data packets; programmed by the SMF over N4 (PFCP).
`DMF`	dflux TinyCore's combined control-plane process bundling the AMF and SMF.
`DPF`	dflux TinyCore's combined data/policy process bundling the AUSF, UDM, UDR, and PCF.
`NSSF`	Network Slice Selection Function — optional dflux TinyCore process for allowed / configured NSSAI.
`SMSF`	SMS Function — optional dflux TinyCore process for SMS over NAS.
`gNB`	The 5G base station (Next Generation NodeB); connects to the AMF over N2 and the UPF over N3.
`UE`	User Equipment — the device (phone, modem, simulator) that attaches to the network.

Interfaces & protocols

Term	Definition
`SBI`	Service-Based Interface — the HTTP/2 + JSON APIs NFs use to talk to each other.
`N1`	Logical interface carrying NAS signaling between the UE and the AMF.
`N2`	Interface between the gNB and the AMF, carrying NGAP over SCTP.
`N3`	User-plane interface between the gNB and the UPF, carrying GTP-U.
`N4`	Interface between the SMF and the UPF, carrying PFCP.
`N6`	Interface between the UPF and the external data network (the internet).
`NAS`	Non-Access Stratum — signaling between UE and core (registration, auth, session management) over N1.
`NGAP`	NG Application Protocol — the N2 control protocol between gNB and AMF.
`PFCP`	Packet Forwarding Control Protocol — how the SMF programs the UPF over N4.
`GTP-U`	GPRS Tunnelling Protocol, User plane — tunnels user packets over N3, keyed by TEID.
`SCTP`	Stream Control Transmission Protocol — the reliable transport NGAP runs over on N2.

Identities

Term	Definition
`SUPI`	Subscription Permanent Identifier — the subscriber's permanent identity; an IMSI in dflux TinyCore.
`SUCI`	Subscription Concealed Identifier — the privacy-protected (encrypted) form of the SUPI sent over the air.
`IMSI`	International Mobile Subscriber Identity — the MCC + MNC + MSIN that identifies a SIM.
`GUTI`	Globally Unique Temporary Identity — a temporary identity the AMF assigns so the SUPI isn't sent repeatedly.
`PLMN`	Public Land Mobile Network — an operator's network, identified by MCC + MNC.
`MCC`	Mobile Country Code — the country part of a PLMN (e.g. `001` for test networks).
`MNC`	Mobile Network Code — the operator part of a PLMN (e.g. `01`).
`TAC`	Tracking Area Code — identifies a tracking area (a group of cells) for UE location and paging.

Authentication & security

Term	Definition
`5G-AKA`	5G Authentication and Key Agreement — the primary mutual-authentication procedure between UE and core.
`Milenage`	The cryptographic algorithm set that derives authentication vectors from K and OPc.
`SIDF`	Subscription Identifier De-concealing Function — the UDM role that decrypts a SUCI back into a SUPI.
`K`	The 128-bit subscriber permanent key, shared between the SIM and the UDR.
`OPc`	Operator variant of the OP key, derived per subscriber and stored instead of the bare OP.

Slicing & sessions

Term	Definition
`NSSAI`	Network Slice Selection Assistance Information — the set of slices (S-NSSAIs) a UE is configured for.
`S-NSSAI`	Single NSSAI — one slice identifier, made of an SST and an optional SD.
`SST`	Slice/Service Type — the standardized slice category (e.g. `1` = eMBB).
`SD`	Slice Differentiator — an optional value distinguishing slices of the same SST.
`DNN`	Data Network Name — names the data network a PDU session connects to (e.g. `internet`).
PDU session	Protocol Data Unit session — the connectivity (and IP address) established between a UE and a data network through the UPF.
`QoS`	Quality of Service — the treatment a traffic flow gets (priority, bit rate, latency).
`QFI`	QoS Flow Identifier — marks packets so the UPF and gNB apply the right QoS flow.
`5QI`	5G QoS Identifier — a standardized value mapping to a packet-forwarding behavior (delay, loss, priority).
`AMBR`	Aggregate Maximum Bit Rate — a cap on total throughput, applied per session or per subscriber.

User-plane forwarding

Term	Definition
`PDR`	Packet Detection Rule — tells the UPF how to match incoming packets to a session.
`FAR`	Forwarding Action Rule — tells the UPF what to do with matched packets (forward, drop, buffer).
`QER`	QoS Enforcement Rule — applies rate limiting and QoS marking to matched packets.
`TEID`	Tunnel Endpoint Identifier — identifies a GTP-U tunnel on N3.
`F-SEID`	Fully-qualified Session Endpoint Identifier — identifies a PFCP session on a given node (IP + SEID) across N4.