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Signalling aspects 3

Annex A

Scenarios related to flexible network service combination on BNG
(This annex forms an integral part of this Recommendation)

A.1 Scenarios of the service route path
Network services are deployed on the service platform. A packet goes through the BNG and network service
in the intended order for service handling. The intended order of the service handling is called the service
route path. The service route path is mainly determined by the following key elements:
1) the relationship among the network services;
2) the interactions between the network service and BNG.

Figure A.1 – Example of packet processing by network services

As depicted in Figure A.1, the packets are processed by the network services one by one. The way the packet
is switched to the next network service for processing should be standardized. Three service route path
scenarios are introduced in this Annex.

A.1.1 Chrysanthemum service route path
To simplify the network service design, the decision of the network service processing order for a packet is
determined by the BNG.

Figure A.2 – Scenario of Chrysanthemum service route path

As depicted in Figure A.2, the decision about which network service a packet should go to is made by the
BNG. The decision is made only in a single node. Every packet goes back to the original node from where it
came when the network service handling is done. As the service route path looks like the shape of a
chrysanthemum, it is called the Chrysanthemum service route path.
In the Chrysanthemum service route path scenario, the network service does not need to know the next
handling network services for the packet. Each network service only focuses on service specific handling and
is not coupling with other network services.

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