MPLS

Summary

The MPLS Working Group session at IETF 125 focused on the continued evolution of MPLS Network Actions (MNA), Network Resource Partitioning (NRP) identifiers, and enhancements to RSVP-TE Fast Reroute (FRR). The chairs provided a status update on several documents moving toward publication, including the MNA header which is now with the RFC Editor. Key discussions revolved around the encoding of NRP selectors in post-stack data, the export of MNA information via IPFIX and BGP-LS, and refining OAM error codes for resource-aware networking.

Key Discussion Points

WG Status Update

Presenter: Adrian Farrel Slides: 01 - WG Status Update

Errata: A new errata was filed regarding IPv6 unnumbered interfaces. Kitan noted he would provide detailed feedback on the mailing list to initiate discussion.
Document Progress:
- draft-ietf-mpls-mna-hdr is with the RFC Editor.
- draft-ietf-mpls-mna-ps-hdr has passed Working Group Last Call (WGLC) and is awaiting final shepherding.
- Four new documents have been adopted as WG items since the last meeting.

Carrying NRP related Information in MPLS Packets

Presenter: Jie Dong Draft: draft-ietf-mpls-mna-psd-nrp-selector Slides: 02 - Carrying NRP related Information in MPLS Packets

The draft defines carrying the NRP Selector ID using MNA Post-Stack Data (PSD).
Discussion:
- Joel Halpern suggested changing the title to explicitly mention "MNA post-stack data" for clarity. Jie Dong agreed.
- Pavan Beeram questioned the need for "ancillary data" in the encoding, suggesting the ID should be enough to map to policy. Jie Dong explained it was for future scalability (e.g., per-NRP statistics).
- Jim Guichard asked about the rationale for a 32-bit selector ID compared to smaller stack-based IDs. Jie Dong noted this aligns with 3GPP network slice mapping requirements discussed in the TEAS WG.

STAMP Extensions for Reflecting STAMP Packet MPLS Extension Headers

Presenter: Rakesh Gandhi Drafts: draft-ietf-mpls-stamp / draft-ietf-mpls-stamp-pw Slides: 03 - STAMP Extensions for Reflecting STAMP Packet MPLS Extension Headers

This work aims to allow STAMP to support hop-by-hop and edge-to-edge measurements in MNA-enabled networks by reflecting extension headers.
Adrian Farrel inquired about implementation status; Rakesh Gandhi confirmed there is no implementation at this time.

Supplement of BGP-LS Distribution for SR Policies and State

Presenter: Miao Liu Slides: 04 - Supplement of BGP-LS Distribution for SR Policies and State

The presentation discussed how to report MNA in-stack information via BGP-LS.
Discussion: Tarek Saad asked if there were use cases for reporting general MPLS Label Stack Entries (LSEs) beyond MNA. Miao Liu responded that MNA is currently the primary driver for reporting LSEs with non-zero TC and TTL fields.

Export of MPLS Network Action (MNA) Information in IPFIX

Presenter: Miao Liu Slides: 05 - Export of MPLS Network Action (MNA) Information in IPFIX

Proposed new IPFIX Information Elements (IEs) to export MNA substack and post-stack information to avoid complex parsing at the collector. No comments were raised by the floor.

Signaling Optimization Objective and Bounded Metrics for MPLS Fast Reroute Backup LSP Tunnels

Presenter: Pavan Beeram Slides: 06 - Signaling Optimization Objective and Bounded Metrics for MPLS Fast Reroute Backup LSP Tunnels

Proposed an extension to RFC 4090 to allow an ingress node to signal specific optimization objectives (e.g., minimize delay) and bounded metrics for backup LSPs.
Discussion:
- Adrian Farrel suggested aligning the terminology and objective functions with PCEP.
- Tarek Saad raised a point regarding how multiple primary LSPs might share a backup path if they have different optimization objectives.
- Rakesh Gandhi noted that headends already consider many constraints (SRLG, affinity) and asked if the goal was to replicate all headend logic at the PLR. Pavan Beeram clarified the goal is to provide basic, missing constraints while remaining extensible.

OAM for Network Resource Partition (NRP) in MPLS Network

Presenter: Li Yan Slides: 07-Operations, Administration and Maintenance (OAM) for Network Resource Partition (NRP) in MPLS Network

Updates to extending LSP Ping/Traceroute for NRP-specific verification.
Discussion:
- Joel Halpern challenged the "NRP resource unavailable" error code, arguing that if an NRP is provisioned, its resources are available by definition. He suggested the issue might be congestion, not availability.
- Tarek Saad suggested splitting the error code for "unknown NRP" into two: "NRP not supported" and "NRP not configured/provisioned."
- Adrian Farrel and Joel Halpern recommended using the term "NRP not provisioned" for better clarity.

Decisions and Action Items

Draft Rename: Jie Dong to rename draft-ietf-mpls-mna-psd-nrp-selector to include "MNA post-stack data" in the title.
Errata: Kitan to provide feedback on the IPv6 unnumbered interface errata thread.
OAM Error Codes: Li Yan to revise the error code definitions in the OAM for NRP draft based on feedback from Joel Halpern and Tarek Saad.

Next Steps

draft-ietf-mpls-mna-ps-hdr will proceed to shepherding and then to the IESG.
The authors of the RSVP-TE FRR extension and the NRP OAM document requested Working Group adoption; the chairs will take this to the mailing list.
Miao Liu requested feedback from the MPLS WG on the MNA-related IPFIX and BGP-LS definitions currently being discussed in OPSAWG and IDR.

Automatic IETF Minutes