Page 1441 - 5G Basics - Core Network Aspects

Signalling aspects 3

5 Conventions

In this Recommendation:
The keywords "is required to" indicate a requirement which must be strictly followed and from which no
deviation is permitted, if conformance to this Recommendation is to be claimed.
The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely
required. Thus, this requirement need not be present to claim conformance.
The keywords "can optionally" indicate an optional requirement which is permissible, without implying any
sense of being recommended. This term is not intended to imply that the vendor's implementation must
provide the option, and the feature can be optionally enabled by the network operator/service provider.
Rather, it means the vendor may optionally provide the feature and still claim conformance with this
Recommendation.

6 Introduction of BNG Pool

With the fast development of broadband service/network, higher requirements for BNG are needed.
Accordingly, the deployment of BNG in current carrier network has the following problems needed to be
solved:
– BNG is usually deployed individually according to its geographical region, and there is usually no
redundancy/protection function deployed among multiple BNG devices, which cannot meet the
requirement of the high reliability for high value services, e.g. IPTV, customer leased-line services.

– With the low reliability, BNG is not allowed to serve a large number of users simultaneously to avoid
interrupting users' service. So this leads to a great waste of BNG resources.
– BNG usually shows significantly different resource utilization depending on its deployment location,
carried services, etc., which may also lead to the waste of BNG resources.
– The individual deployment of BNG increases the complexity of BNG's OAM.
– Because BNG has a high requirement for the deployment environment (e.g. the power supply,
transmission resources), the individual deployment of BNG would increase the CAPEX.

In order to solve the above problems, BNG pool architecture is proposed. In this architecture, BNG devices
will be deployed in a moderately centralized manner. One BNG pool is composed of multiple BNG devices
locating in a central office or multiple central offices which are geographically adjacent to each other. Using
BNG pool architecture has the following advantages:
– The BNG devices in one pool can provide the backup protection for each other, which can achieve
the high reliability to meet the requirements of high value services.
– The BNG devices in one pool can realize the resource sharing and load balancing, which can improve
the overall resource utilization.

– The BNG pool can be maintained and operated as a whole, which can simplify the OAM.
– Moderately centralized deployment of BNG devices can reduce the demand for central office, which
can greatly reduce the CAPEX.

Note that the hot-standby technology has been deployed to solve the reliability of BNG. However, this
technology is based on the totally distributed manner, and it is complicated to configure, monitor, manage
and coordinate among the BNG devices. It will bring high pressure for BNG's control plane. While the BNG
pool architecture is based on the centralized control mode, which can help to realize centralized/unified
coordination and scheduling, and achieve the load balancing among the BNG devices. Under the control by
a centralized controller, pressure of control plane of BNG can be alleviated, unified OAM for BNG devices can
be achieved, and differentiated requirements from the applications can be satisfied through open APIs.

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