19 Facts About MPLS

MPLS operates at a layer that is generally considered to lie between traditional definitions of OSI Layer 2 and Layer 3, and thus is often referred to as a layer 2.

The similarity between Frame Relay, ATM, and MPLS is that at each hop throughout the network, the label value in the header is changed.

MPLS technologies have evolved with the strengths and weaknesses of ATM in mind.

MPLS is designed to have lower overhead than ATM while providing connection-oriented services for variable-length frames, and has replaced much use of ATM in the market.

MPLS recognizes that small ATM cells are not needed in the core of modern networks, since modern optical networks are fast enough that even full-length 1500 byte packets do not incur significant real-time queuing delays.

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The current advantages of MPLS primarily revolve around the ability to support multiple service models and perform traffic management.

MPLS offers a robust recovery framework that goes beyond the simple protection rings of synchronous optical networking.

When MPLS was conceived, label switching was faster than a routing table lookup because switching could take place directly within the switched fabric and avoided CPU and software involvement.

MPLS Header is added between the network layer header and link layer header of the OSI model.

Label-switched path is a path through an MPLS network, set up by the NMS or by a signaling protocol such as LDP, RSVP-TE, BGP.

MPLS can make use of existing ATM network or Frame Relay infrastructure, as its labeled flows can be mapped to ATM or Frame Relay virtual-circuit identifiers, and vice versa.

MPLS is able to work with variable length packets while ATM transports fixed-length cells.

An MPLS connection is unidirectional—allowing data to flow in only one direction between two endpoints.

MPLS uses label stacking to accomplish this while ATM uses virtual paths.

Biggest advantage that MPLS has over ATM is that it was designed from the start to be complementary to IP.

In practice, MPLS is mainly used to forward IP protocol data units and Virtual Private LAN Service Ethernet traffic.

Major applications of MPLS are telecommunications traffic engineering, and MPLS VPN.

MPLS has been originally proposed to allow high-performance traffic forwarding and traffic engineering in IP networks.

MPLS can exist in both an IPv4 and an IPv6 environment, using appropriate routing protocols.