Session Date/Time: 20 Mar 2025 06:00

mpls

Summary

The MPLS working group meeting covered several topics, including updates on RFCs and drafts, presentations on LSP ping and trace route enhancements for IOM, bootstrapping active performance monitoring sessions, and in-situ OAM realization in MPLS networks. A significant portion of the meeting was dedicated to a discussion about MPLS label assignment modes (upstream/downstream) and their implications for DCB labels in the context of beer.

Key Discussion Points

RFC and Draft Updates: Several new RFCs have been published, and multiple drafts are in the RFC editor queue or with the ISG. The MNA IOM draft was accepted, and updates were provided on several other drafts.
LSP Ping and Trace Route for IOM: A presentation on extensions to LSP ping and trace route for IOM capabilities discovery in MPLS networks was given. There was discussion on whether LSP ping is the right mechanism for discovering node capabilities and whether IGP or management plane might be more appropriate. Scalability was also raised as a concern.
Bootstrapping Active Performance Monitoring Sessions: A presentation covered a draft addressing bootstrapping active performance monitoring sessions over MPLS LSP using stamp and LSP ping. There was discussion on whether stateful or stateless approaches are preferable.
In-Situ OAM Realization: The new working group draft merging two approaches for realizing in-situ OAM (INSTAC data and post-tag data) was discussed. A question was raised regarding how transit nodes can efficiently determine whether they should process post-tag data, and concerns were raised about limited fast forwarding buffer space.
MPLS Label Assignment Modes (Upstream/Downstream) and DCB Labels: This topic consumed a large portion of the meeting. The discussion centered on whether DCB labels should be considered downstream-assigned given that they are globally coordinated. There were proposals to update the beer encapsulation RFC to clarify the meaning of the "protocol field" and specify whether the label should be looked up in the default or context-specific ALFIB. Different viewpoints were presented, with some arguing for a new code point to represent "global" or "coordinated" labels. Others preferred modifying the existing code points for reasons of implementation simplicity.

Decisions and Action Items

LSP Ping for IOM: Authors to consider the scalability of the solution and alternative methods of node capability discovery.
In-Situ OAM Realization: Continue discussion on how to signal the presence and location of post-tech data MNA.
DCB Labels and MPLS Assignment Modes:
- Authors of RFC 9573 (DCB) will add an errata stating that the label is to be looked up and installed in the default FIB.
- The meaning of protocol field values 1 and 2 in beer encapsulation RFC will be clarified to specify whether the label should be looked up in the default ALFIB or the context-specific ALFIB, respectively. No new code point will be defined.
- The MPLS working group will not directly update or deprecate RFC 5331.

Next Steps

Authors to revise drafts based on the feedback from the meeting.
Continue discussions on the mailing lists for unresolved issues.
The beer working group will handle updates to the IANA registry regarding the "protocol field" in the beer header and have discussions about the relevant terminology in that venue.