to-discover PEs with endpoints par- ticipating in a particular virtual network service. This dynamic discovery is event based allowing very fast rehoming of services and rerouting for state changes (e.g., failure of one side of a dual attachment or injection or withdrawal of a layer 3 route). This is ideal for cloud movement of a VNF instance, allowing the associated customer access VLANs to move with the VNF (see Figure 12.11). 12.6 FUTURE EVOLUTION OF NETWORK EDGE In this chapter, we reviewed the drivers, both business and technical, for the recent rapid evolution of network edge platforms. Disaggregation of hardware and software for packet processing has fundamentally changed the architecture and cost structures for the network edge. This leads to a new interplay and intersection between software and hardware to optimize the performance, yet maintain maximum flexibility. In this section, we examine the future evolution of the network edge. Building the Network of the Future EVPN Flexible Cross Connect EVPN VPWS DSLAM WAN Underlay FIGURE 12.11 EVPN rerouting psuedowires. Packet edge networking evolution remains a very dynamic and active area of research and devel- opment. The transition from vertically integrated switch and router platforms based on custom silicon packet processors and proprietary software, to disaggregated open software platforms based on merchant silicon or x86/CPU, has led to many new options and innovations. With these new options come an array of choices to optimize overall cost and performance. In this section, we briefly review three broad evolution themes. Open packet processors Open configuration and programming packet processors Open control of packet processors 12.6.1 OPEN PACKET PROCESSORS Packet processors have rapidly evolved from closed custom silicon and/or software to new open inter- faces based on open standards and open source software. The drive to openness was first manifested with merchant silicon packet processors where the suppliers provided software development kits SO 