You may have recently often heard the acronym, MPLS , used in the same sentence as "IP VPN," "voice over IP" or "core networks." It stands for "multi-protocol label switching," and it seems to show up almost everywhere relating to internet protocol "IP."

According to Tara Seals from Phone Plus Magazine, network providers 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 than frame relay connections or point to point T1's or point to point DS3's if the locations are further apart.

One problem with IP networks is creating the same quality levels that exist in traditional phone lines, the “five nines” reliability in the SLA. This is where the QoS (quality of service) or CoS (Class of Service) becomes quite important.

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, MPLS carriers can run multiple applications on the same packet infrastructure, creating a multi-service network that is merely a transport mechanism. The backbone doesn’t 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 don’t affect the quality. This is where CoS/QoS is critical for the MPLS to provide the performance needed.

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 connection a natural choice for the converged core network and a popular delivery mechanism for new services at the edge (like IP VPNs).”

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 MPLS 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 all locations to talk to each other. A bank with 10 branches would need 100 permanent virtual circuits to be a meshed architecture. This becomes very costly. For a frame relay network, there are also bandwidth constraints: A frame connection is still a frame connection, IP-enabled or not, and it tops out at DS3 speeds (45 mbps). An MPLS connection can be connected at much higher speeds than a DS3 circuit .

MPLS connections are critical to effectively deploying an IP-based, converged network that satisfies customer SLA requirements.

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 AT&T, to Sprint, to Qwest, to Verizon, to Level3, to Global Crossing to the RBOCs, most have services up and running on the new core.

If you're a business with two or more locations and would like to consider an MPLS service, please contact us at shopforbandwidth.com to get competitive MPLS quotes for your office locations.