Page 1406 - 5G Basics - Core Network Aspects

3 Signalling aspects

6 Introduction of SBAN

Broadband business has become the main source of revenue for carriers, and broadband access network
(BAN) plays an important role in carriers' network. But there are still a number of challenges which need to
be addressed in BAN, especially for IP radio access network (RAN), see Appendix I.

BAN includes two types of nodes: access nodes and aggregate nodes. The access nodes connect the user
devices, such as: base transceiver station (BTS), evolved node B (eNodeB), or customer edge (CE), and the
aggregate nodes connect the network devices, such as radio network controller (RNC), the IP metropolitan
area network nodes or the IP backbone network nodes. The network topology between access nodes and
aggregate nodes can be ring, chain or tree structure. Taking IP RAN for example, IP RAN usually uses a ring
structure for network robustness, which is depicted in Figure 6-1.

Figure 6-1 – Ring structure of BAN

In Figure 6-1, access ports belong to access nodes that connect user devices, and aggregate ports belong to
aggregate nodes that connect other network nodes. Within access nodes and aggregate nodes, there are
internal ports that connect to other access nodes or other aggregate nodes.

There are a lot of network equipment and multiple protocols in BAN, and the network topology of BAN is
complicated, so network deployment and configuration of BAN requires complex implementation and high
maintenance costs. On the other hand, new value-added services and applications emerge rapidly, but it
takes weeks or even months for networks to incorporate them.
According to the above, SBAN aims to enable to separate the forwarding function and control function of
network equipment, and to provide an open interface to applications and network managers.
The functional entities of the SBAN model consist of forwarding devices, SDN controller, SDN application,
southbound interface and northbound interface. Considering the large number of access nodes, there is a
difference between SBAN and other SDN scenarios. It is difficult for the SDN controller in SBAN to link all
forwarding devices directly, especially for all access nodes. So in SBAN, the SDN controller only links the
aggregate nodes, and abstracts the aggregate nodes and the access nodes as a single node composed of
access ports and aggregate ports, which is called an SBAN node and depicted in Figure 6-2.

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