MPLS network diagram gallery

This view of MPLS from Altera could apply to any network, but is relevant to telecom. Data enters the system through an Edge Label Switching Router. This is where packets are classified and receive their labels. The crossed arrows represent points at which packet labels are switched (hence Multi-Protocol Label Switching) to continue along the LSP (Label Switched Path). Routing labels are switched as the packet moves from router to router, with label being swapped at each hop in order to properly direct them to the next forwarding point. Labels have local significance only. MPLS labels are stripped when the packets exit the MPLS portion of the network.

This diagram from UTStarcomm gives a broad overview of mobile networks from the cell site to mobile backhaul over MPLS into the network core, moving from left to right. It notes that multiple backhaul types (T1/E1, ATM, and Ethernet) can make use of MPLS. One of the advantages of MPLS is that it can encapsulate multiple technologies for transport so that it can serve legacy networks and assist operators with network convergence.
As Glen Hunt, principal analyst for network routing and infrastructure at Current Analysis put it, network operators “are not building next-generation mobile backhaul networks, or next-generation business networks, or residential networks — they’re building one network. They might not always put all the traffic on the same equipment or the same network links, but one of the things they’re looking at is going to a common set of gear that can support all kinds of services, all types of traffic.”


These two diagrams from Juniper Networks show (top) a traditional TDM Radio Access Network and (bottom) an MPLS-based Radio Access Network. The typical response for the need for more capacity in TDM networks has been to add additional point-to-point capacity. However, the evolution toward MPLS within telecom networks offers an opportunity for aggregation and a flatter, all-IP infrastructure from the cell site into the network core. It also offers more network control and traffic management options.
“With MPLS, you have a much more determined path from point A to point B through the network,” said Joe Whitehouse, director of marketing for the network technologies division at MetroSwitch, a major MPLS provider to OEMs.
Infonetics Research predicts that by 2013, a majority of mobile operators and transport providers will have over 90% of their cell sites connected with IP/ethernet and 70% of mobile operators plan to use MPLS at their cell sites.

This diagram from Telco Systems emphasizes that various types of traffic can be carried by MPLS networks. As illustrated, the network is carrying mobile backhaul traffic from cell sites,virtual private lines or virtual private networks for enterprise, and in this case, traffic from DSLAMs (digital subscriber line access multiplexer, devices connecting multiple DSL subscribers to the network backbone). Regardless of the traffic type, MPLS labels can be applied to properly prioritize and route the traffic, allowing operators and customers to reap the benefits of the additional efficiencies built into MPLS.

This MPLS diagram gives greater detail on the role of MPLS PE (Provider Edge) routers in MPLS networks, which maintain the virtual routing and forwarding (VRF) tables for individual customers and serve both label distribution and label removal functions. It also illustrates how traffic can be carried differently for different customers – such as a pseudowire framework in the case of customer C. Contributed by Aman Yadav, graduate student at the University of Colorado, Boulder’s Interdisciplinary Telecom Program.