MPLSlabels

MPLSLabels refers to the set of labels used in a multiprotocol label switching (MPLS) network to forward packets along predetermined paths. In MPLS, a label is a short, fixed-length identifier placed between the data-link and network layers. Packets are bound to a Forwarding Equivalence Class (FEC) at the network edge, after which a label stack is attached and the packet is switched through the core by label lookup rather than IP routing.

Label switching routers (LSRs) examine the top label, swap it for the next one according to their forwarding tables, and forward the packet toward the next hop. The label stack can be pushed or popped as the packet traverses the network. In many deployments, the penultimate hop performs PHP (penultimate Hop Popping), removing the outer label before IP forwarding at the last hop.

Labels and their distribution are established by protocols such as LDP (Label Distribution Protocol) for general bindings and RSVP-TE (Resource Reservation Protocol with Traffic Engineering) for explicit label-switched paths. These mechanisms create LSPs that define the route through the MPLS network, while remaining independent of the underlying IP addressing. Labels enable multiprotocol operation, including IPv4, IPv6, or VPN contexts.

Common use cases include MPLS VPNs for customer traffic separation via VRFs, traffic engineering to optimize paths, fast reroute for resilience, and quality-of-service differentiation. MPLS improves forwarding performance and scalability in large networks and integrates with existing IP routing.

Limitations and considerations include added control-plane complexity, reliance on consistent label distribution, and security concerns such as misconfiguration. MPLS is typically deployed inside operator networks to complement IP routing rather than replace it.