ution for taking fiber very close to the customer premises, as close as 250 m or less for G.fast implementations. Regarding G.fast as the real ultra-broadband solution (with bitrates up to 1 Gbit/s), the practical lengths of the copper wires are in the range of 30-50 (i.e. existing wiring inside buildings), where on 30 m loops it should support at least 0.5 Gbit/s on a single twisted pair. Meanwhile, VDSL2 Vplus (with its 35 MHz fre- quency spectrum) supports longer loop lengths (such as 200 Mbit/s over 500 m) and also up to a couple of hundred subscribers (that is, denser solution) compared with G.fast. This makes VDSL2 Vplus the best possibility for deployment of ultra-broadband FTTN/FTTcurb (fiber to the node/fiber to the curb) over medium local loop lengths. Overall, Vplus bitrates are comparable to bitrates that can be achieved by many FTTH (fiber to the home) deployments. 4.1.2 Cable Ultra-Broadband Access Another copper access technology that has been used massively since the end of the twentieth century is coaxial cable access (or shortly, cable access). However, where cable access is used it is typically implemented in a hybrid optical-coaxial (HFC) manner, that is, only the last mile (or meters) toward the end-user are implemented via coaxial cable, while the rest of the network toward the operator core network is optical. For Internet access via the cable access networks, DOCSIS (Data Over Cable Service Interface Spec- ification) is the CableLabs standard. In particular, CableLabs developed architectures for integrated cable networks for different services, including initially analog TV and radio, then digital TV, HDTV, video-on-demand (VoD), broadband Internet access, and telephone services provided via VoIP. A typical architecture for cable access networks is given in Figure 4.2. It consists of several network segments, which include home IP network, DOCSIS, PacketCable, and the core IP network. DOCSIS exists in three main versions and several subversions, all listed in Table 4.3. Initially appearing