November 1, 2004

5 Min Read
MPLS, the Network of the Future

By Tara Seals

MPLS: you may have heard the acronym used in the same sentence as “IP VPN,” “voice over IP” or “core networks.” What is this mysterious thing, this multi-protocol label switching, which seems to show up almost everywhere IP is discussed? You may not need to know all the pings and the zings involved, but a basic knowledge of MPLS can open up new doors of opportunity.Carriers are migrating their infrastructures from circuit-switched phone networks to packet-based architectures, so they can deliver advanced services such as VoIP, IP video streaming, IP virtual private networks and other Internet-enabled offerings in a cheaper, more cost-effective manner. But this is not just a change in underlying technology the shift has ramifications on how channel partners market advanced services.Overcoming the QoS ObjectionOne problem with IP networks is creating the same quality levels that exist in traditional phone lines, the famed five nines reliability. The problem has been well-documented, and many potential customers may be leery of IP-based services for this reason. Being able to explain MPLS is a key to overcoming that.In the TDM world, the application IS the network, be it data or voice, and the service is simply measured by usage and distance. If the network quality is good, then so is the service.In IP, carriers can run multiple applications on the same packet infrastructure, creating a multi-service network that is merely a transport mechanism. The backbone doesnt inherently know which applications it is carrying. This abstraction layer between services and transport makes delivering carrier-grade service difficult, because packets from applications like voice or video need to be prioritized over those from e-mail or remote back-up batching, where jitter and latency dont affect the quality.While carriers have worked to put more intelligence in the core by purchasing cutting-edge service-aware hardware and software platforms, a big way they are getting packet networks up to snuff is with multi-protocol label switching, or MPLS.In an MPLS network, incoming packets are assigned a label by a special router, depending upon the application sending the packets. They are then forwarded along a label switch path, where label switch routers (LSRs) make forwarding decisions based on what the label says. At each hop, these LSR traffic cops strip off existing labels and apply new ones that tell the next LSR how to forward the packets at the next traffic stop. In this way, MPLS allows IP to differentiate between different applications and classes of service.According to the MPLS & Frame Relay Alliance, MPLS was designed to address the shortcomings of IP and deliver the benefits of a connection-oriented infrastructure, such as the optimization and traffic engineering. These benefits, coupled with features such as enhanced resilience using MPLS fast re-route and DiffServ coding to enhance the QoS of the IP network, make MPLS a natural choice for the converged core network and a popular delivery mechanism for new services at the edge (like IP VPNs).Understanding Market Forces: Why IP?Faced with declining growth in traditional voice and data offers, carriers want to sell high-margin IP services that attract new customers. IP-enabling the existing legacy network is expensive and inefficient, and doesnt offer the sorts of long-term benefits like reduced transport costs and customer self-provisioning that IP backbones can offer. Additionally, converging services down to one network significantly bolsters operational efficiency for carriers that have been maintaining separate voice and data networks for eons.Meanwhile, customer demand for converged services that are cheaper and easier to manage is growing. For instance, the popularity of IP-enabled core business process applications like customer relationship management and supply chain management are driving the adoption of technologies such as IP VPNs, which allow for a meshed architecture. That means that one connection into an IP cloud per location is all it takes to support all IP applications between all locations. In contrast, while frame relay can be IP-enabled to support enhanced services, every location must be connected to every other frame location for them all to talk to each other. A bank with 10 branches would need 100 permanent virtual circuits to be a meshed architecture. And there are bandwidth constraints: A frame connection is still a frame connection, IP-enabled or not, and it tops out at DS3.As noted, MPLS is critical to effectively deploying an IP-based, converged network that satisfies customer SLA requirements.The UpshotNot surprisingly, nearly every major facilities-based carrier has announced an IP MPLS strategy for its core network in order to move to the next level. From MCI to Global Crossing to the RBOCs, most have services up and running on the new core.Eventually, all services will be applications on an IP backbone. In a converged network scenario, an access network is still required to reach to the customer site, according to a white paper from the MPLS & Frame Relay Alliance. The access network is connected to the network providers MPLS core using a provider edge device. This means that the converged network could offer MPLS as the convergence layer in the core but still work with a number of other technologies at the aggregation points to the network and also in the access network. Service convergence also means supporting multiple Layer 2 services (e.g. ATM, frame relay, Ethernet) over a common core, thereby extending the reach of existing services or allowing provision of todays standard services like ATM or frame relay over the new network.However, the MPLS network isnt replacing the existing TDM core yet, so the two do exist side-by-side. And because carriers have spent significantly in capital expenditure to build IP MPLS backbones out, ostensibly to save money in the long run, they need to start booking revenue on it to justify the expense in the near-term. Channel partners can expect carrier partners to push IP backbone-based services heavily while supporting large install bases of existing private line, voice and frame relay customers.Armed with a working knowledge of MPLS, channel partners can make sure customers understand the quality differentiation that MPLS-based service offers. Combining this knowledge with the ability to clarify the benefits of convergence (cheaper network maintenance, quick application deployment and flexible LAN architecture, to name a few) sets the stage to encourage existing customers to migrate to IP networking, which in turn opens up the market for high-value, revenue-generating advanced services.Tune in next month when we discuss what, exactly, convergence means.

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