Page 86 - ITU-T Focus Group IMT-2020 Deliverables

3 ITU-T Focus Group IMT-2020 Deliverables

NOTE 5 – whether it utilizes the NF Repository function or an enhancement of the DNS server to reach this
functionality is left for CT WG to determine.
5) To support "stateless" NFs (where the "compute" resource is decoupled from the "storage" resource
that stores state as opaque data), 3GPP will specify (possibly by referencing) interfaces from NFs to
a data storage function. NFs may use data storage function to store opaque data.

6) Exposure of information as a service is supported as follows:
– Network functions may expose structured information (e.g., UE related information) to other
network functions as a capability. Exposure of information can trigger actions in the consuming
NF.
NOTE 6 – What information is to be exposed will be determined during the normative phase.

– A network function may use information exposed by other network functions.
– A network function may expose information that it received from another NF.
The Network Exposure Function receives information from other network functions (based on exposed
capabilities of other network functions). It may store the received information as structured data using a
standardized interface to a data storage network function (interface to be defined by 3GPP). The stored
information can be "re-exposed" by the NEF to other network functions and used for other purposes such as
analytics.

6.1.1.2.2.1 Solution 2.1: IRF based network function interconnection model solution update
(Source: Cisco)

This solution is applicable only to the interconnection of the network functions. The network function's
definition and its functionalities are assumed to be defined by solutions to other key issues.

Assuming that only one of the control plane access network function is required to interface with only one
of the control plane core network function, the interconnection model between them can be point-to-point
interface based, e.g. control plane core network function 1 interfaces with control plane access network
function 1 over a point-to-point interface between them. However, if it is decided to allow multiple control
plane access network functions to interface directly with multiple control plane core network functions then
the principles of this solution can be extended to interconnect control plane access network and core
network functions as well.
Similarly, it is assumed that the user plane core network functions are required to interface only with their
respective control plane core network functions. And hence the interconnection model between them can
be point-to-point interface based. However, if it is decided to allow any control plane function to interface
with any user plane function then the principles of this solution can be extended to interconnect control
plane and user plane core network functions as well.
The solution assumes that multiple control plane core network functions are required to interact with
multiple other control plane core network functions in the next generation core network architecture.
NOTE – Unless explicitly specified, the term "network function" refers to "control plane core network
function" in this solution. Just for the sake of understanding the "control plane core network functions" in
the EPC context are MME, control plane of PGW, PCRF, HSS, control plane of TDF, TSSF, RCAF, SCEF etc.

This solution is applicable only to the interconnection of the network functions. The network function's
definition and its functionalities are assumed to be defined by solutions to other key issues.
Assuming that only one of the control plane access network function is required to interface with only one
of the control plane core network function, the interconnection model between them can be point-to-point
interface based, e.g. control plane core network function 1 interfaces with control plane access network
function 1 over a point-to-point interface between them. However, if it is decided to allow multiple control
plane access network functions to interface directly with multiple control plane core network functions then
the principles of this solution can be extended to interconnect control plane access network and core
network functions as well.

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