ncept of open compute platforms, the network cloud architecture extends the key benefits of NFV to network access elements and also brings them under SDN control. 11.2 WHAT MAKES ACCESS NETWORKS DIFFERENT Since NFV is an extension of concepts introduced for cloud computing in centralized data centers, some fundamental characteristics of access networks make them different from cloud computing functions and core network functions; this prevents access networks from being able to run in their entirety on conventional data center hardware platforms. As shown in Figure 11.1, access networks are inherently distributed and cannot have their func- tions completely centralized. The endpoints of the access network are not located in data centers- they are located at the customer premise, such as homes or businesses, and are incorporated into customer-owned devices such as mobile handsets. Standards define the protocols and behaviors that allow these endpoints to connect to the network. These standards support limited transmission distances, which means that network access elements that directly interface with the customer must be located close to customer locations and devices. The distributed nature of the access network endpoints would not in and of itself stop the com- pute and networking components of the access network from being fully centralized. If the trans- port component of the access network provided a fully transparent constant bitrate pipe from each endpoint device to the centralized location, with each transparent pipe having negligible delay and operating at the full peak speed of the endpoint device, it would allow for a high degree of central- ization. This type of transport would be a good way to characterize the connectivity between com- pute nodes and the top-of-rack switches in a data center, and it is the key to allowing the compute functions to be fully virtualized within a data center. Network Terminating Shared Access Equipment / User Equipment Access Media Wireline Example: Optical Optical Line 