Feature Description

Multiprotocol Label Switching (MPLS) is a protocol that uses labels to route packets instead of using IP addresses. UPF supports MPLS to switch MPLS traffic using VPP as the data plane forwarder.

On ASR 5500, the NP4c network processor generates and processes MPLS traffic. On VPC-DI, IFTask generates and processes MPLS traffic.

VPC-SI uses VPP as the data plane forwarder. VPP encapsulates and decapsulates subscriber traffic with MPLS labels. VPP provides support for multiple data plane features that include the MPLS stack as a separate graph node. This feature helps to differentiate between different customer VRFs and support corporate APNs having different addressing models and requirements.

UPF supports MPLS encapsulation over the following interfaces for 5G deployments using VPP:

  • N6—N6 is the interface between UPF and data network (DN).

  • N9—The N9 interface connects two UPFs. It is the interface between Intermediate I-UPF (Visited) and UPF Session Anchor (Home).

The following figure depicts the different interfaces used for MPLS encapsulation in UPF.

MPLS Interfaces

UPF supports the following functionalities for MPLS:

  • Uses VPP MPLS stack to send the MPLS labeled packet.

  • Uses VPP MPLS stack to process the incoming labeled MPLS packet.

  • Uses only MP-BGP as the label distribution protocol.

  • VPPCTL CLI commands display the FTN, FIB, and ILM tables that are in VPP, for debugging and comparing values with boxer configuration.