on-critical applications. As the IP network moves from a best-effort network to one that supports more mission- critical business applications and real-time consumer and business applications, The Next-Generation Network Infrastructure Network Ethernet IP/MPLS Network Backbone Service Edge Broadband Router Network Figure 10.10 The multiservice edge the requirements for edge equipment change. Today, applications such as gaming, streaming media, and VoIP represent only a small percentage of U.S. IP traffic, but it is expected that the volume will grow as IP networks add the requisite QoS and high-availability capabilities. While these mission-critical applications allow service providers to increase the revenues from their IP networks, they also demand a higher level of service reliability. The gradual migration to voice-over-packet also introduces the require- ment for stringent QoS, further emphasizing the need to provide the predictability and control that TDM networks offer. Five-nines reliability (i.e., 99.999%, or less than 5 minutes of downtime per year) will become an increasingly critical compo- nent of IP networks. The Architecture of the Multiservice Edge The multiservice edge has three main architectural requirements: High reliability-We can address the need for reliability by providing for built-in redundancy in the form of redundant switch fabrics and compo- nents, stable software that offers five-nines reliability, support for in-service upgrades, and the ability to easily integrate into the service provider's oper- ational support systems. In the realm of availability, the ability to perform hitless software upgrades is a necessity, as are hot-swappable components Chapter 10 Next-Generation Networks and modules. Modular software code is required for maximum flexibility. Finally, the ability to detect failures and reroute traffic while detecting and reporting faults is required. Scalability-The multiservice edge must support increasing amounts of traffic, increasing numbers of users, and the ability 