MPLS: the magic behind the myths

This article reviews the key differences between traditional IP routing and the emerging multiprotocol label switching (MPLS) approach, and identifies where MPLS adds value to IP networking. In various corners of the industry MPLS has been held up as the solution to IP QoS, gigabit forwarding, network scaling, and traffic engineering. Each of these expectations is critically considered in the light of developments in conventional gigabit IP routers. It is shown that MPLS adds the ability to forward packets over arbitrary non-shortest paths, and emulate high-speed 'tunnels' between IP-only domains-capabilities critical to service providers who need to better manage resources around their backbones, or who are planning IP VPN services. However, it is also argued that the technology required to support IP QoS and gigabit forwarding is not unique to MPLS. A network of gigabit IP routers or switches may be entirely sufficient for QoS and performance if traffic engineering is not a requirement.