The Network: Access, Transport & Core

The network that inventory and activation act on — access, transport and core domains, the IP networking that runs through them, and the path a mobile, voice, broadband or enterprise VPN service takes end to end.

Resource Inventory and activation are about network elements: what exists, what is assigned to whom, and what configuration must change for a service to work. Architects who have only seen the network as a box labelled "network" at the bottom of a BSS/OSS diagram struggle to reason about either. This section is the map the rest of the module assumes — the three network domains, the IP networking that runs through all of them, and the path a real service takes end to end.

How to use the diagram

Pick a service to light the path it takes and dim everything it does not touch. Select any element to see what it is, what Resource Inventory records about it, and how it is activated — with links to the sections that go deeper.

Service

Pick a service to light the path it takes through the network.

IP networking — runs through access, transport and core

ElementsRoutersSwitchesFirewallsLoad balancersDNSSDN / automation controllers

FeaturesIPv4 / IPv6Routing: OSPF · IS-IS · BGPMPLSSegment routingQoSTraffic engineeringL2 / L3 VPNNetwork slicingMonitoring & telemetry

Tap any element to see what Resource Inventory records about it and how it is activated.

Access connects users and sites; transport carries traffic between access and core; core delivers services and manages subscribers, sessions and data. IP networking runs through all three.

What each domain owns

	Access	Transport	Core
Job	Connect end users and sites: radio, fibre, copper, cable, Ethernet access	Carry traffic between access and core at high capacity: aggregation, metro, backbone	Deliver services: admit subscribers, set up sessions, apply policy, route to other networks
Typical elements	gNB / eNB, OLT, ONT, splitter, CPE, access switch, DSLAM, CMTS	Aggregation, metro, core and regional routers; DWDM and microwave links	5GC (AMF, SMF, UPF), BNG, IMS (P/I/S-CSCF), PCF, NEF, NSSF
Typically operated by	RAN and fixed-access engineering, with field operations for physical plant	IP and transport engineering, network operations centre	Core and cloud platform teams; the functions increasingly run on telco cloud
What Resource Inventory holds	Physical plant and devices, ports, PON trees; logical VLANs and ONT IDs. Passive plant cannot be discovered	Devices, ports, links and topology; logical interfaces, VRFs, IP addresses, MPLS / SR paths	Network function instances as virtual or cloud-native resources; address pools; slice instances
Touched by a customer order?	Yes for fixed and enterprise access (OLT, CPE, access switch); no for the RAN	Only at the edge: a VPN changes the PEs; the backbone is built capacity	Rarely: per-subscriber data lives in UDM / HSS and AAA, not in function configuration

The last row is the one that shapes an OSS design. Activation is concentrated at the edges of the network — the OLT, the CPE, the provider edge router, the subscriber data stores — while most of the transport and core is configured when capacity is built, not when a customer orders. A fulfilment flow that tries to configure every element in a path for every order is solving the wrong problem; one that ignores the subscriber data stores in the core will activate nothing at all.

Where inventory and activation touch the network

Resource Inventory sees three kinds of thing. Physical resources — chassis, cards, ports, fibre, splitters — are the classic inventory of access and transport. Logical resources — VLANs, IP addresses, VRFs, ONT IDs, telephone numbers — are what fulfilment assigns. Virtual and cloud-native network functions in the core are resources too, but they scale and move, so their record has to be fed from the orchestrator that runs them rather than designed by hand. 7.2 and 7.3 cover how each is modelled.

Activation reaches each domain by a different route. Fixed and enterprise access is configured through the access EMS/NMS or NETCONF/YANG; IP/MPLS transport through network orchestrators and SDN controllers; core functions through NFV or cloud-native orchestration, with per-subscriber data written to UDM / HSS and AAA/RADIUS. 7.4 covers the activation patterns, 7.5 the EMS/NMS layer, and 7.6 the controllers and interfaces below ROM.

Not every element can tell inventory the truth

Active elements can be discovered and reconciled from the network. Passive plant — fibre routes, splitters, ducts — cannot: its record is only as good as the last field update. Existing customers on older access technologies were often connected before today's models existed, so their inventory lineage is incomplete. A brownfield inventory programme should expect the passive and legacy parts to need the most reconciliation effort.

What this picture leaves out

The diagram shows the network, not the systems that manage it. Each domain has its own EMS, NMS or controller above it, and often more than one. Those layers are where ROM's resource orders actually land — they are the subject of 7.5 and 7.6.

Section 7.1 Key Takeaways

Access connects users and sites, transport carries traffic between access and core, and core delivers services and manages subscribers, sessions and data; IP networking runs through all three.
Each service takes its own path: FTTH ends at the BNG, mobile data and voice at the 5GC and IMS, and an enterprise L3VPN never touches the core at all.
Activation is concentrated at the network edges and in subscriber data stores; most transport and core configuration is built capacity, not per order.
Resource Inventory holds physical, logical and virtual resources — and passive plant is the part no discovery tool can verify.