MPLS Network Actions: Technological Overview and P4-Based Implementation on a High-Speed Switching ASIC

2024-10-27

arXiv.org

AI Summary

To address the deployment challenges of novel network functions—such as link-level packet-loss measurement and network slicing bandwidth reservation—in MPLS networks, constrained by limited special-purpose label space, scarce hardware resources, and shallow label stack depth, this paper proposes the MPLS Network Actions (MNA) framework. MNA features the first hardware prototype implemented on a 400 Gb/s P4-programmable switch chip; introduces node-level capability parameterization and a lightweight signaling mechanism to enable incremental upgrades on resource-constrained devices; and explicitly defines the processing boundaries for In-Stack Data (ISD) and Post-Stack Data (PSD). Experimental evaluation demonstrates that MNA incurs negligible latency overhead, maintains compatibility with Active Measurement Methodology (AMM) and IPv6 extension headers, and successfully validates both packet-loss measurement accuracy and slice bandwidth reservation feasibility. Additionally, we propose a hardware header-parsing optimization path that ensures backward compatibility.

Technology Category

• Machine Learning: Hardware-aware ML
• Multiagent Systems: Mechanism Design
• Planning, Routing, and Scheduling: Plan Execution and Monitoring

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Responsible Web: Measurement, analysis, and circumvention of Web censorship
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems

Abstract

In MPLS, packets are encapsulated with labels that add domain-specific forwarding information. Special purpose labels were introduced to trigger special behavior in MPLS nodes but their number is limited. Therefore, the IETF proposed the MPLS Network Actions (MNA) framework. It extends MPLS with new features, some of which have already been defined to support relevant use cases. This paper provides a comprehensive technological overview of MNA concepts and use cases. It compares MNA to IPv6 extension headers (EHs) that serve a similar purpose, and argues that MNA can be better deployed than EHs. It then presents P4-MNA, a first hardware implementation running at 400 Gb/s per port. Scalability and performance of P4-MNA are evaluated, showing negligible impact on processing delay caused by network actions. Moreover, the applicability of MNA is demonstrated by implementing the use cases of link-specific packet loss measurement using the alternate-marking-method (AMM) and bandwidth reservation using network slicing. We identify header stacking constraints resulting from hardware resources and from the number of network actions that must be supported according to the MNA encoding. They make an implementation for hardware that can only parse a few MPLS headers infeasible. We propose to make the number of supported network actions a node parameter and signal this in the network. Then, an upgrade to MNA is also feasible for hardware with fewer available resources. We explain that for MNA with in-stack data (ISD), some header bits must remain unchanged during forwarding, and give an outlook on post-stack data (PSD).

Problem

• Extends MPLS with new network actions
• Compares MNA to IPv6 extension headers
• Implements MNA in hardware at 400 Gb/s

Innovation

• MPLS Network Actions framework
• P4-based hardware implementation
• Scalable high-speed switching ASIC