For service providers, maximizing fiber bandwidth utilization and service offerings on a Metro Network is key to generating revenue. Wave Division Multiplexing (WDM) is a fiber optic multiplexing technology that can increase a fiber's bandwidth up to 64-fold. Multi Protocol Label Switching is a sophisticated hardware/software packet switching solution to provide scalable, traffic engineered end-to-end L2/L3 VPN services. Both MPLS and WDM can be used simultaneously, thus the term MPLS over WDM. MRV is a leading equipment vendor in both WDM and MPLS technologies and offers an excellent combined solution for service providers.

MPLS

MPLS networks are built using sophisticated Label Switch Routers (LSR), which run various protocols to exchange routing and label information. Packet switching decisions are based on 20-bit MPLS labels that appear near the beginning of each packet. Labels can be stacked (ie. 2 labels in one packet) and since the labels are 20-bit, MPLS scales very well.

Label Edge Routers (LER) reside on the ingress / egress on MPLS networks and perform three important functions for the MPLS network. First, they setup a Label Switch Path (LSP) through the MPLS network from ingress LER to egress LER. An LSP is also referred to as a tunnel. Secondly, LERs signal the services between LERs. These services are commonly VPNs and come in different flavors, L2, VPLS or L3 BGP-VPN. Lastly, LERs receive packets from the non-MPLS domain (Ethernet or IP/Ethernet packets) and add an MPLS header which includes an MPLS label for switching through the MPLS domain. On the egress, the LER removes the MPLS header.

WDM

WDM is a method of transmitting data from different sources over the same fiber optic link at the same time whereby each data channel is carried on its own unique wavelength. The result is a line with an aggregate bandwidth that increases with the number of wavelengths employed. In this way WDS technology can maximize the use of fiber optic infrastructure that is available; what would normally require two or more fiber links instead requires only one.

MRV provides a range of Multiplexer / Demultiplexers (Mux/Demux), Add/Drop Multiplexer / Demultiplexers, Cross Connects and Optical Amplifiers to provide the necessary yet simple components to build powerful WDM systems. Using these components, various network topologies can be deployed, such as Point-to-Point, Hub and Spoke, Rings and Meshes.

MPLS over WDM

MPLS switches are layer 2.5 devices and the most common layer 2 interface for an MPLS switch is Ethernet. Since Ethernet is specified to use either fixed optics or pluggable optics (ie. SFPs), MPLS switches can connect directly to a WDM network.

MPLS switches multiplex VPN services over the core using 20-bit labels found inside the MPLS header of packets. WDM equipment multiplexes optical signals using different wavelengths. Both of these technologies work seamlessly together and compliment each other.