Page 355 - 5G Basics - Core Network Aspects

Core network aspects 1

is used to identify data streams towards applications, the port number is a resource for multi-
connection. Usually, the port number is categorized as a well-known port number (for example,
port number 21 is used only for FTP and port number 23 is used for telnet) or an unspecified
port number.

ii) Stream (session) number: As for port numbers, if a stream (session) number is used to identify
data streams towards applications, the stream (session) number is a resource of multi-
connection. Stream (session) number is not related to TCP/UDP transport protocol, but is
related to stream control transmission protocol (SCTP) transport protocol.
d) Application layer: The resources for multi-connection in the application layer are identified as
uniform resource locator (URL), domain name, session, access point name (APN), IP multimedia
private identity (IMPI) and IP multimedia public identity (IMPU). The attributes of each resource are
defined as follows:
i) The resource for multi-connection in the application layer is closely related to the specific
applications and access technology. URL is related to WWW service. Domain name is related to
DNS service. APN, IMPI, IMPU are related to the specific access technology and system.

6.2 Resource identifiers
This clause identifies the resources to support the multi-connection functions and capabilities specified in
[ITU-T Y.2027] and [ITU-T Y.2251] in a high-level approach.
The resource identifiers (IDs) are defined by reusing existing resource IDs or can be newly defined.
a) Service ID (SVID): According to service decomposition [ITU-T Y.2251], a service can be decomposed
into several service components. To achieve service decomposition and composition, the
identification of each service component is recommended to support one or more applications. In
that case, a new SVID is required. For example, the service ID may be defined by using a public
service ID as in 3GPP.
b) Session ID (SEID): The definition of session describes a temporary telecommunication relationship
among a group of objects in the service stratum [ITU-T Y.2091]. Regarding the multi-connection
aspect, session can be used for session combination capability. An application can be supported by
one or more sessions, so session IDs should be identified. For example, the session ID may be defined
by using a combination of IP addresses and ports like a session defined in IETF.
c) IP flow ID (FLID): The current IP flows can be identified by a flow ID in IP packets to support a service.
However, it is required that these flows be distinguished by service components in order to support
the service decomposition and composition. Therefore, IP flow ID should be identified to support
the service components. In addition, these IP flow IDs should be linked to specific network
interfaces.
d) Access network ID (ANID): To provide the UE with a multi-connection environment, different types
of access networks should be connected simultaneously to the UE. The UE should be able to identify
the different access networks before using them, and to choose the appropriate one, depending on
policy, QoS, etc. for multi-connection.
e) Interface ID (IFID): Regarding the UE aspect with respect to multi-connection, a UE should have
several heterogeneous logical/virtual and physical interfaces. Therefore the UE should identify the
interface IDs. To achieve utilization of multi-connection, the UE has to choose the corresponding
interfaces.

7 Configuration of resource identifiers

The subscriber and the operator are required to handle the resource IDs to achieve efficient utilization of the
resource in the multi-connection environment. From the UE point of view, the subscriber is recommended
to configure the resource IDs to provide benefits from multi-connection through multi-connection capability
[ITU-T Y.2251].

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