IETF 121 MPLS WG Meeting
Date/Time: Wednesday Session II, November 6, 2024 13:00 - 14:30 (local)
Room: Liffey Hall 1
Chairs: Tarek Saad/Nicolai Leymann/Tony Li
Secretary: Mach Chen
Slides:
https://datatracker.ietf.org/meeting/121/session/mpls/
Codimd for Notes Taking:
https://codimd.ietf.org/notes-ietf-121-mpls/
Meetecho:
http://www.meetecho.com/ietf121/mpls/
Zulip:
https://zulip.ietf.org/#narrow/stream/121-mpls
WG Status Update (Agenda Bashing) - 13:00
Duration: 10 mins
Presenter: WG Chairs
[Greg]: we reached out to the other authors of the IOAM-dex
documents and we are working on collaborating/combining into one
draft.
Stateless MNA-based Egress Protection (SMEP) - 13:10
ID:
https://datatracker.ietf.org/doc/draft-ihle-mpls-mna-stateless-egress-protection-00
Duration: 15 mins
Presenter: Fabian Ihle
[GregM]: did you think about local protection too? This may be
applicable to SR-MPLS (for example)
[Fabian]: It is possible, but for transit protection many other
approaches
[Sasha]: encoding mentions 1 label but do we need to specify the
interface on PLR? This could work with SR.
[Stewart]: on genralizing the idea, need repair for every hop and
that does not scale. An alternative, is to have a different action
(POP-N). Does not necessitate rebuilding the MPLS stack.
[JieD]: encoding, ... Scope, how do you control which PLR to
process. If there are multiple PLR, then multiple NAS with repair
stack for each.
[Fabian]: yes.
Update on MNA Implementation Experience in P4 - 13:25
Duration: 20 mins
Presenter: Fabian Ihle
[Jag]: is there any difference between the implementation between
version-5 and version-8
[Fabian]: we implemented version-5 and it worked. Latest version
can carry AD for format B LSE
[Rakesh]: we can discuss if it makes sense to shorten the NASL
length
[Greg]: one of the concerns I have when putting AD in PSD makes
challenging for parsing.
[Fabian]: correct. For PSD, we need 51 LSE NAS + PSD. Even if
using 2 LSE (and P bit) to indicate PSD may be lots of overhead.
[Greg]: if we have multiple MPLS payloads (e.g. PW or BIER), then
we can push the MNA PSD even deeper.
[Rakesh]: In the MNA-HDR solution, we have a flag and offset. Does
it help to reach the data?
[Fabian]: from P4 implementation, it makes this complicated. Not
so useful.
Performance Measurement Using Simple Two-Way Active Measurement
Protocol (STAMP) for Segment Routing Networks - 13:45
ID: https://datatracker.ietf.org/doc/draft-ietf-spring-stamp-srpm-16
Duration: 10 mins
Presenter: Rakesh Gandhi
[GregM]: the loopback mechanism is useful when no clock
synchronization between 2 nodes. You can divide by 2 to infer.
[Tony]: since this depends on the MNA-HDR draft (which WG agreed
will move to experimental), this document may need to move to
experimental.
[Rakesh]: we need to investigate if an informative status would be
impacted by referencing an experimental doc.
Label Switched Path (LSP) Ping for Segment Routing (SR) Path Segment
Identifier with MPLS Data Planes - 13:55
ID:
https://datatracker.ietf.org/doc/draft-ietf-mpls-spring-lsp-ping-path-sid-02
Duration: 5 mins
Presenter: Xiao Min
[Greg]: Does the PCE document ensure that the allocated SIDs at
egress are known at the ingress?
[Xiao]: if path-segment is not used in the network
[Greg]: what happens if the headend is not aware of the state
present at the egress? Both specs are normative.
[Ketan]: Path-segment is a label that belongs to the egress (from
its label space). Some mechanism is needed to make this known to the
headend. I think we should progress this work independent how state
is reported from egress to ingress.
[Greg]: the candidate path is selected by the ingress. If we can
not synchronize state between ingress and egress, then this is not
useful. If BGP can not synchronize this state e/i, then we should
not have it in scope. In any way, the document needs some rework.
[Ketan]: solution does not require control plane to synchronize.
This can be done by config/provisioning. There is another option
using PCEP. BGP may have challenge doing this.
Deterministic Networking specific MNA - 14:00
ID: https://datatracker.ietf.org/doc/draft-varmir-mpls-detnet-mna-00
Duration: 15 mins
Presenter: Greg Mirsky
[TonyL]: Lou Berger suggests that ECMP in DETNET is 'not
recommended' not 'prohibited'
[XueyanS]: there is some overlap for this with another document.
[Greg]: the options can be combined for different deployments. One
of the advantages is we can have single seq-no. space. We will be
going to the DETNET WG to get their feedback. We are open to other
feedback.
Total presentation time: 75 mins
Shuffling time: 15 mins