IPMPLS

IPMPLS, short for IP over MPLS, is an architecture that carries IP traffic across a multiprotocol label switching (MPLS) network. In an IP/MPLS network, edge routers perform IP routing and push one or more MPLS labels onto IP packets as they enter the core. Core routers forward packets solely on their MPLS labels, using label switching, until they reach the egress router, which pops the label and delivers the original IP packet to its destination. The approach separates the IP control plane from the data plane and enables efficient, scalable forwarding and traffic engineering.

Packet forwarding is driven by LSRs and label distribution is handled by protocols such as LDP or RSVP-TE. LDP distributes simple labels for normal forwarding, while RSVP-TE can reserve resources along an LSP to support quality of service and bandwidth guarantees. IP/MPLS networks support VPN services (MPLS VPNs) by using VRFs and route distinguishers, enabling isolated customer traffic over a shared backbone. They also enable fast reroute, improving network resilience.

Advantages include scalable forwarding, reduced CPU load on routers, and the ability to apply QoS and TE policies along the path. Limitations include complexity of management, reliance on signaling protocols, and the need for careful design to prevent misconfiguration. IP over MPLS remains widely deployed in service provider cores and large enterprises, often as the backbone for IP VPN services. In recent years, Segment Routing MPLS and EVPN-based solutions have emerged as evolutions or alternatives to traditional IP over MPLS, offering simplified control planes and broader scalability.