MPLS and MPLS-TE

Multiprotocol Label Switching (MPLS) is a specification for Layer 3 switching from the IETF. Similar to Cisco's tag switching, MPLS uses labels, or tags, containing forwarding information. These labels are attached to IP packets by the router sitting at the edge of the network and are known as label edge routers (LERs). The routers in the core of the network are known as label switch routers (LSRs) and examine the label more quickly than looking up destination addresses in a routing table, which provides for greater network efficiency.

NOTE

MPLS also is an acronym for Multiprotocol Lambda Switching. In an optical networking system, MPLS is the ability to route a data transmission based on the wavelength of light that carries it. The routing device analyzes only wavelengths (light frequencies) to make its forwarding decision rather than inspecting fields within each packet. The correct spelling of this term is with the Greek "L" for Lambda.

MPLS-Traffic Engineering (TE) increases network utilization by creating a uniform distribution of traffic throughout the network, avoiding congestion on any one path. Traffic engineering does not automatically select the shortest path between two devices; for two-packet data flows, it is possible these packets can take different paths through the network, even if these packets share the same originating and destination sites. This distribution method can use the less-exposed or less-used network resources, enabling the support of differentiated services across the network.

MPLS-TE does not, in itself, provide for QoS to applications. MPLS-TE provides a means to transport this QoS traffic by using traffic engineering to set up paths between originating and destination nodes, in turn meeting service level guarantees (SLGs).