A View from George Swallow


In 1999, Dr. Tony Li wrote, "The long-term impact of MPLS is difficult to anticipate because of the innovations that it enables." Although many innovations have now been revealed, the statement remains essentially true. MPLS is not just a new data-communications technology; it is a new kind of technology. Spawned out of the otherwise ill-fated marriage of IP and ATM, MPLS offers the tight control of ATM while not losing the flexibility found in IP routers. In fact, MPLS adds flexibility to routers. Although a number of important architectural elements contribute to MPLS's success, two aspects have a direct bearing on its future.

The most salient MPLS innovation is its intentionally loose coupling of the control and data planes. In fact, one can barely speak of the MPLS control plane because the intersection of control elements between L3-VPNs, traffic engineering, and pseudowires is minimal. This loose coupling has allowed the independent creation and evolution of multiple MPLS applications. Yet, not only can these applications run in the same network, but they can also be used in conjunction with one another. VPN data flows can be traffic-engineered completely independently of the VPN control plane. On the other hand, QoS preferences can be applied to any particular VPN.

This loose coupling offers service providers the flexibility to create a wide range of service offerings and enables the rapid evolution of service capabilities. It also offers equipment vendors architectural freedom in creating new applications.

The second architectural element is that MPLSunlike ATMwas not created as a standalone self-contained system. Instead, MPLS is closely bound to IP. Not only does MPLS coexist in the same network as IP, but MPLS also depends directly on IP protocols for its control plane(s). IP has come to dominate the world's data communications and, as the trend progresses, it appears destined to dominate communications of all forms. With such ubiquitous acceptance, any technology that pretends to compete head-to-head with IP will be a nonstarter for the foreseeable future.

MPLS, however, does not attempt such competition. Instead, it coexists with and complements IP. It enables value-added services above and beyond what can be offered with IP alone. Further, it adds value to basic IP services. Traffic engineering and particularly the fast reroute capabilities of MPLS TE are being deployed in IP networks. As the volume of voice and video traffic grows on IP networks, users will begin to demand higher levels of service. These demands can be met only by the capability to reroute around failures quickly enough to not noticeably degrade service. In fact, the performance of MPLS TE is so good that some providers are eliminating their Sonet/SDH multiplexers and running IP+MPLS directly over DWDM.

Service providers have long sought to have a single, converged network upon which they can offer all services. ISDN and B-ISDN gave us Frame Relay and ATM but failed in their quest for an integrated services digital network (ISDN). Frame Relay and ATM have been, and remain, important technologies, but their primary mission has been to carry IP traffic. IP is the world's only ubiquitous data communications technology; supplanting that infrastructure would be a monumental task. Inserting MPLS into that infrastructure is simply a natural evolution and an evolution that is well underway.

MPLS is enabling IP networks to efficiently and effectively provide IP VPNs, carry Frame Relay and ATM traffic, emulate Sonet and other circuits, and of course provide Internet connectivity all on a single infrastructure. Through MPLS TE, this infrastructure can be made sufficiently robust to meet the requirements of voice and video traffic. Truly we are entering the day of converged networking. The future belongs to IP+MPLS.

For more information, read Tony Li's "MPLS and the Evolving Internet Architecture," IEEE Communications Magazine, Volume 37, No. 12, December 1999.




MPLS and Next-Generation Networks(c) Foundations for NGN and Enterprise Virtualization
MPLS and Next-Generation Networks: Foundations for NGN and Enterprise Virtualization
ISBN: 1587201208
EAN: 2147483647
Year: 2006
Pages: 162

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