Page 160 - ITU-T Focus Group IMT-2020 Deliverables

3 ITU-T Focus Group IMT-2020 Deliverables

Figure 7.2-3 – Virtual BBUs

Table 7.2-3 – Virtual BBUs

Items Descriptions

Overview Various generations BBUs and various operators BBUs can be implemented by software on the
same hardware.
Benefits – Computation resources can be flexibly allocated to each virtual BBU on demand.
– The BBU function can be dynamically reconfigured and adjusted.
Challenges to – Diversified types of terminals, traffic, network operator, and RAN (D.7.7-1 to 4)
be clarified – Coordination of power saving across FH/BH/Radio System (D.9.2.1)
– Power saving by resource optimization (D.9.2.2)

While the challenges shown in Table 7.2-3 are partially covered in Table 7.1-1, it needs management/control
for the computation resources in addition. This is for further study.

7.3 Data Plane Programmability
7.3.1 Background [Ref.7.3-1]

Although the synergy between SDN and NFV has only recently been discussed, they have been proposed
separately. While SDN primarily focuses on the programmability on the control of networking, NFV aims at
implementing data processing functions in software on top of virtual machines (VMs) that exist today as
hardware network appliances. The clear distinction of the focuses of SDN taking care of networking and NFV
of computation may allow scalable construction of programmable infrastructure, since data packets can be
programmatically redirected by SDN and can be programmatically processed by NFV.

However, we observe two limitations in this model of separation of SDN and NFV, leaving an interesting
research area as a gap between them. First, SDN often defines predetermined interface, so called
southbound interface or SBI, mainly for the sake of standardization purpose. It is control plane software
including controllers that can be programmed in software above SBI (and not to mention, above so called
north-bound interface or NBI), but data plane that implements data forwarding and redirection often
remains to be implemented in hardware as in, e.g., OpenFlow switches. If we could arbitrarily define data
plane by software, i.e., software-defined data plane, in carefully designed sandboxes such as virtual machines
inside network equipment, we should be able to enhance the data plane functionalities, e.g., those related
to OAM, and publish the SBI for controllers to use them. Second, NFV is so far limited to implementing
network appliances in software, and deals neither with crafting new protocols nor with OAM functionalities,

154