Page 318 - 5G Basics - Core Network Aspects

1 Core network aspects

1 Scope
This Recommendation describes the flow-based service continuity mechanism in a multi-connection
environment. This Recommendation also describes scenarios, requirements, information flow mechanisms
and security of flow-based service continuity in a multi-connection environment. For information on other
aspects outside of the scope of this Recommendation, such as security and charging for flow-based service
continuity in a multi-connection environment, see [ITU-T Y.2251].

2 References

The following ITU-T Recommendations and other references contain provisions which, through reference in
this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated
were valid. All Recommendations and other references are subject to revision; users of this Recommendation
are therefore encouraged to investigate the possibility of applying the most recent edition of the
Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is
regularly published. The reference to a document within this Recommendation does not give it, as a stand-
alone document, the status of a Recommendation.
[ITU-T Y.2027] Recommendation ITU-T Y.2027 (2012), Functional architecture of multi-connection.
[ITU-T Y.2028] Recommendation ITU-T Y.2028 (2015), Intelligent access selection in
multi-connection.

[ITU-T Y.2029] Recommendation ITU-T Y.2029 (2015), A multi-path transmission control in
multi-connection.

[ITU-T Y.2251] Recommendation ITU-T Y.2251 (2011), Multi-connection requirements.

3 Definitions

3.1 Terms defined elsewhere
This Recommendation uses the following terms defined elsewhere:

3.1.1 connection [b-ITU-T X.200]: A connection is an association established for the transfer of data
between two or more peer-(N)-entities. This association binds the peer-(N)-entities together with the (N-1)-
entities in the next lower layer.
3.1.2 multi-connection [b-ITU-T Y.2252]: The collection of several connections between two or more
peer-(N)-entities simultaneously. At least one of the connections is associated with a physical layer
connectivity different from the rest of the connections. All connections are coordinated with each other to
provide service to higher layer entities.
3.1.3 multi-connection user equipment (MUE) [ITU-T Y.2027]: A user equipment which can support two
or more network connections simultaneously under the control of a network enhanced for multi-connection
capability.

3.1.4 service continuity [b-ITU-T Q.1706]: The ability for a moving object to maintain ongoing service
including over current states, such as user's network environment and session for a service.

3.1.5 service transfer [ITU-T Y.2251]: Act of moving, one or more services or service components
belonging to a single multi-connection UE, from one access network associated with one interface of the
multi-connection UE to another access network(s) associated with other interface(s) of the multi-connection
UE.
3.1.6 IP flow [b-RFC 3917]: A flow is defined as a set of IP packets passing an observation point in the
network during a certain time interval. All packets belonging to a particular flow have a set of common
properties. Each property is defined as the result of applying a function to the values of:

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