 hops, which means traffic takes shorter, congested paths rather than longer, uncongested paths, leading to network hotspots and inconsis- tent performance. Chapter 10 Next-Generation Networks A lot of attention is being focused now on the MPLS environment, which was born out of Cisco's tag switching. MPLS, which was designed with large-scale WANs in mind, was originally proposed by the IETF in 1997, and core specifications were completed in 2000. By plotting static paths through an IP network, MPLS gives ser- vice providers the traffic-engineering capability they need, and it also helps them build a natural foundation for VPNs. Remember that traffic engineering allows ser- vice providers to control QoS and optimize network resource utilization. MPLS is one of the most significant developments in IP. MPLS is not an IP net- work, although it uses IP routing protocols such as OSPF and IS-IS and can run in routers. MPLS is not an ATM network, although it can use repurposed ATM cell switch hardware. MPLS is yet another type of network: It is a service-enabling technology. MPLS is a general-purpose tunneling mechanism that can carry IP and non-IP payloads. It uses label switching to forward packets or cells through the network, and it can operate over any data link layer. MPLS separates the control plane from the forwarding plane. It thus enables the IP control plane to run on devices that cannot understand IP or recognize packet boundaries. The MP part of MPLS means it's multiprotocol-it is an encapsulating protocol that can transport a multitude of other protocols. LS indicates that the pro- tocols being transported are encapsulated with a label that is swapped at each hop. A label is a number that uniquely identifies a set of data flows on a particular link or within a particular logical link. The labels are of only local significance. They must change as packets follow a path-hence the switching aspect of MPLS. Another benefit of MPLS is its potential to unite IP and optical switching under one route-provisioning 