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MPLS

Multiprotocol Label Switching (MPLS)

Recall: Packet Switching and Circuit Switching

Suppose an IP packet is sent from Mumbai, India to Kansas City, Kansas using Packet switching

Packet_Switching_Example_1 Packet_Switching_Example_2 Packet_Switching_Example_3 Packet_Switching_Example_4 Packet_Switching_Example_5

Packet switching is flexible and data path is not fixed. But processing IP information at every router slows down transmission.

In contrast, circuit switching method is a fixed-path switching method. It is reliable but more expensive.

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MPLS

MPLS allows IP packets to be forwarded at layer 2 (switching level) without being passed up to layer 3 (routing level).

Let’s take a look how MPLS works with the same IP packet sent from Mumbai, India to Kansas City, Kansas.

MPLS_Example_1 MPLS_Example_2 MPLS_Example_3 MPLS_Example_4

These routers act like switches on a local network.

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As a result, MPLS offers potentially faster transmission than traditionally packet switching networks 👏.

In summary, MPLS can create end-to-end paths that act like circuit-switched connections, but deliver layer 3 IP packet.

As we know, routing is the layer 3 function while switching is the layer 2 function. MPLS makes those routers on the Internet act like switches on a local network.

$\rightarrow$ MPLS is also called 2.5 layer protocol.

Reference

MPLS - Multiprotocol Label Switching (2.5 layer protocol)