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Core network aspects 1

Figure I.4 – SAME network slice for MVNO scenario

I.4 Separation of control function and forwarding function
In these scenarios, the control function and forwarding function of mobile packet core gateway are
separated. The GW control function is mainly in charge of mobility management and session management.
The GW forwarding function is responsible for packet encapsulation/decapsulation for tunnelling, packet
forwarding rules, forwarding performance and QoS level. The tunnel/packet routing/switch information and
tunnel parameters are transferred from control function to forwarding function. The charging function could
be realized on control function, forwarding function or both, which depends on the implementations. The
separation of the GW's control function and forwarding function could improve the deployment flexibility,
such as centralized control function and distributed forwarding function deployment, without changing the
interfaces to other legacy functions.

Scenario 1: flexible deployment of separated control function and forwarding function
Descriptions
When the GW is separated into control function and forwarding function, the control function is centralized
and deployed with other mobile packet core control function such as mobility management function, and
policy function.
The centralization of control functions makes the operation and management easier; in addition, NFV
technology can be used for the centralized control functions to achieve benefits such as resource sharing,
scheduling and faster deployment.
The separation of control function and forwarding function in the same equipment enables the scaling
independent of each other.
By separation of control function and the forwarding function, the capacity of forwarding function data
handling can naturally be enhanced by increasing the number the forwarding equipment.
When the control function deployed in centralized manner and the forwarding function in distributed
manner, the distributed forwarding functions could realize traffic localization, because voice or video service
mostly happens between users in the same region. Distributed forwarding function localizes the traffic, which
will reduce the transport cost dramatically. Further, when the distributed forwarding function resides closer
to the subscriber, the latency could be reduced.

Preconditions
The GW is separated into control function and forwarding function, and the control function and forwarding
function can be deployed in a flexible way.

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