Mapping 5G slice to Transport Network slice with UDP Source Ports
draft-ietf-dmm-tn-aware-mobility-32

[Ballot comment]
Hi Uma, John, Sridhar, Jeff, and Luis,

The changes made since -26 [1] address most of the comments raised in my previous ballot [2]. Thank you.

Cheers,
Med

[1] https://author-tools.ietf.org/iddiff?url1=draft-ietf-dmm-tn-aware-mobility-26&url2=draft-ietf-dmm-tn-aware-mobility-32&difftype=--html

[2] https://mailarchive.ietf.org/arch/msg/dmm/D8NNJXcvIHk8V1Cz-W3LwZvFT2E/

[Ballot comment]
Thanks to the authors and the WG for their work on this document.

I support Med's DISCUSS on the normative reference  classification.
Several references are required to implement or safely deploy this mechanism:

- RFC 9543 defines the IETF Network Slice Service, the AC/SDP terminology
  and service characteristics used in Section 3.3, and the security
  requirements incorporated by Section 6. Moving it from normative in v29
  to informative in v31 is a regression.
- draft-ietf-dmm-udp-tunnel-acaas-extn defines the source-port/range YANG
  augmentation on which the specified provisioning depends.
- TS 29.281 defines GTP-U UDP transport and source-port behavior that this
  document uses and constrains.
- RFC 3948 is required as it specifies the ESP-in-UDP procedure that is used
  by this document.
- RFC 8085 is normative to the extent that the document relies on its
  source-port entropy, flow-affinity, or security guidance.

I also share Med's concern on whether there has been a liaison with 3GPP to
review this work. The mechanism relies directly on 3GPP TS 28.541 and
TS 29.281 and describes how 3GPP user-plane and management functions
select and provision the source-port mapping. I am not sure whether the
proposal was formally communicated to, or reviewed by, the relevant 3GPP
groups. Please confirm whether a liaison statement was sent or those groups
reviewed the mechanism. If no formal review has occurred, please coordinate
with the appropriate groups and I suggest that the responsible AD holds
this document in IESG Evaluation until then.

The remaining comments are inline in the idnits output of v31. Please look
for the  tag at the end to ensure that the complete review is shown.

121   internet.  Since the 3GPP Single Network Slice Selection Assistance
122   Information (S-NSSAI) is not visible to TNs, the source UDP [RFC768]
123   port number of the GTP-U (or UDP encapsulated GTP) bearer is used to
124   convey a mapping to the TN slices on each 3GPP interface (i.e., F1-U,
125   N3, N9).  The standard ephemeral source port space assigned by IANA
126   is sufficient for any realistic deployment scenario for mapping
127   slices.  The number of slices is likely to be far fewer than the
128   source port space available as each slice involves significant

The Dynamic/Private/Ephemeral range is not "assigned by IANA".
RFC 6335 Section 6 defines ports 49152-65535 as Dynamic Ports and says
that they are never assigned; Section 8.1.2 says that they are set aside
for local and dynamic use. RFC 768 defines the UDP header and does not
define the ephemeral range. The Dynamic Ports range also contains 14 bits
of space before any partitioning among slices.

SUGGEST
The Dynamic Ports range, 49152-65535, is set aside for local and dynamic
use by RFC 6335. A deployment can provision values or sub-ranges from this
space for the mechanism described here.

Please add RFC 6335 as the supporting reference. Retain RFC 768 only where
the UDP header itself is being described.

485   PEs can thus be provisioned with a policy based on the source UDP
486   port number (and other identifiers like VLAN) to the underlying
487   transport path and then deliver the QoS/slice resource provisioned in
488   the TN.  The source UDP port number that is encoded is the outer IP
489   (corresponding to GTP-U header) while the inner IP packet (UE
490   payload) is unaltered.  The source UDP port number is encoded by the
491   node that creates the GTP-U encapsulation and therefore, this
492   mechanism has no impact on UDP checksum calculations.  3GPP GTP-U (or
493   IPsec encapsulated GTP-U) payloads are encapsulated in UDP packets
494   and this solution simply uses the outer UDP source port to carry

A UDP source port is neither "the outer IP" nor part of the GTP-U
header. It is a field in the UDP header carrying the GTP-U PDU. The selected
value also participates in the UDP checksum; the relevant property is that
the encapsulating node selects the value before calculating the checksum,
so no later rewrite is needed.

SUGGEST
The slice selector is encoded in the Source Port field of the UDP header
that carries the GTP-U PDU. The encapsulated UE payload is not modified.
The encapsulating node selects the source-port value before calculating
the UDP checksum, so no post-encapsulation rewrite is required.



742   [RFC9611]  Antony, A., Brunner, T., Klassert, S., and P. Wouters,
743               "Internet Key Exchange Protocol Version 2 (IKEv2) Support
744               for Per-Resource Child Security Associations (SAs)",
745               RFC 9611, DOI 10.17487/RFC9611, July 2024,
746               .

RFC 9611 is not cited in the document. Please remove the entry
unless a substantive citation was inadvertently omitted.

[Ballot comment]
Thanks to Jon G. for the great SECDIR review.


* Define "NF" on the first use.

* Thanks to the authors for incorporating Jon's feedback into updates in the Security Considerations section.

[Ballot comment]

# Éric Vyncke INT AD comments for draft-ietf-dmm-tn-aware-mobility-31
CC @evyncke

Thank you for the work put into this document.

Please find below some non-blocking COMMENT points/nits (replies would be appreciated even if only for my own education).

Special thanks to Satoru Matsushima for the shepherd's detailed write-up including the WG consensus *and* the justification of the intended status.

Other thanks to Carlos Bernardos, the Internet directorate reviewer (at my request), please consider this int-dir review:
https://datatracker.ietf.org/doc/review-ietf-dmm-tn-aware-mobility-27-intdir-telechat-haddad-2026-07-06/ (and I have seen John's reply)

I hope that this review helps to improve the document,

Regards,

-éric

Note: this ballot comments follow the Markdown syntax of https://github.com/mnot/ietf-comments/tree/main, i.e., they can be processed by a tool to create github issues.

## COMMENTS (non-blocking)

### Acronyms

Be sure to expand all acronyms before using them, e.g., gNB, CU, UP, ...

### Use of SVG graphics

To make a much nicer HTML rendering, suggest using the aasvg tool to generate SVG graphics. It is worth a try especially if the I-D uses the Kramdown file format ;-)

### Section 3.1

Consider adding a normative reference for `VLAN tags`.

### Section 3.3

The whole text `The source UDP port number that is encoded is the outer IP ... source port to carry slice information` is a little confusing about the use of IPsec: is it transport or tunnel mode ? Moreover is IPsec doing UDP encapsulation to traverse NAT ? A packet format would be beneficial.

Even the next paragraph is unclear whether IPsec itself is encapsulated in UDP (else with ESP the UDP ports are hidden).

### Section 4

As "VPN" is an overloaded term, please add informative references to `VPN, IP/MPLS and SR-TE`.

### Section 6

The ECMP considerations are valid but are not really about "security" and should rather be in an "operational considerations" section.

****
Wassim.Haddad@ericsson.com

[Ballot comment]
Thank you for writing this document.  I note that "IP transport" in this context means transport of IP over UDP over IP, although I see only one transport-related concern;-):

## The way in which the UDP source port number is used appears to prevent the use of source port randomisation,  as recommended in [RFC8085]: a useful technique to mitigate vulnerability to off-path attack. This is expected to be acceptable use. The concern maybe was intended to be included within "To avoid spoofing..", although I'd encourage this to be explicitly stated to note this as a security consideration (perhaps cross-referencing Sect 5.1.1. of 5.1.1) and to link this to mitigations to such attack, where I see IPsec and ACLs suggested as viable possible approaches.

### Noting the above: Should GTP-U packets set and use the IPv6 flow label as an entropy field for load balancing?

## “The source port space (~2^16) for mapping slices is more than sufficient for any realistic deployment scenario.”
- Just to be sure: Is the entire port range (2^16) really available, rather than just the ephemeral port range?

## I found it puzzling that this document speaks of IETF protocols such as UDP and a range of other terms and has no normative references! (I see I-D rev -29 updates this).
— What is the dependency upon TS.28.541-3GPP?
— I am surprised there are not normative references for the terminology used. Is all this defined here?
- I do wonder if RFC 9543 is normative background (f not, what provides the normative basis for the technologies?).

## Is a reference to UDP normative - if not, why?

## This document was reviewed as part of the transport area review team's ongoing effort to review key IETF documents. This review noted a set of concerns that have not been addressed and should be considered and the document updated.

Gorry Fairhurst
(updated comments)

[Ballot comment]
Thank you for writing this document.  I note that "IP transport" in this context means transport of IP over UDP over IP, although I see only one transport-related concern;-):

## The way in which the UDP source port number is used appears to prevent the use of source port randomisation,  as recommended in [RFC8085]: a useful technique to mitigate vulnerability to off-path attack. This is expected to be acceptable use. The concern maybe was intended to be included within "To avoid spoofing..", although I'd encourage this to be explicitly stated to note this as a security consideration (perhaps cross-referencing Sect 5.1.1. of 5.1.1) and to link this to mitigations to such attack, where I see IPsec and ACLs suggested as viable possible approaches.

### Should GTP-U packets set and use the IPv6 flow label as an entropy field for load balancing?

## “The source port space (~2^16) for mapping slices is more than sufficient for any realistic deployment scenario.”
- Just to be sure: Is the entire port range (2^16) really available, rather than just the ephemeral port range?

## I found it puzzling that this document speaks of IETF protocols such as UDP and a range of other terms and has no normative references!
— What is the dependency upon TS.28.541-3GPP?
— Is the reference to UDP normative - if not, why?
— I am surprised there are not normative references for the terminology used. Is all this defined here?

### I do wonder if RFC 9543 is normative background (f not, what provides the normative basis for the technologies?).

Gorry Fairhurst
(updated comments)

[Ballot comment]
Thank you for writing this document.  I note that "IP transport" in this context means transport of IP over UDP over IP, although I see only one transport-related concern;-):

## The way in which the UDP source port number is used appears to prevent the use of source port randomisation, a useful technique to mitigate vulnerability to off-path attack. This is expected to be acceptable use. The concern maybe was intended to be included within "To avoid spoofing..", although I'd encourage this to be explicitly stated to note this as a security consideration (perhaps cross-referencing Sect 5.1.1. of 5.1.1) and to link this to mitigations to such attack, where I see IPsec and ACLs suggested as viable possible approaches.

## I do wonder if RFC 9543 is normative background (f not, what provides the normative basis for the technologies?).

[Ballot discuss]
Hi Uma, John, Sridhar, Jeff, and Luis,

Thank you for the effort put into this specification.

Please find below some pints for DISCUSSion:

# Mobility-awareness & Key technical contribution

CURRENT:
  Following UE handover, the S-NSSAI is mapped seamlessly to
  the corresponding GTP-U (or UDP encapsulated GTP) source port number
  of the newly attached network and can be considered to be "mobility
  aware". 

The reasoning above applies for all schemes that map S-NSSAIs to transport identifiers, such as already those described in RFC 9889.

I’m concerned that the document may be interpreted as if the IETF is recommending this approach compared to other approaches. It would be weird to make such recommendation anyway because that is up to operators to decide the approach that fits their needs and aligned with the capabilities they deploy.

So, instead of tagging this option as the only one which is “mobility aware”, I suggest to position this work as a realization model based on tunnel transport source port/ranges. That is, this is an applicability of the RFC9834 extension defined in I-D.ietf-dmm-udp-tunnel-acaas-extn (3.3 is the main contribution here). I suggest that the title is also updated accordingly.

This approach is consistent with Section 6.5 of draft-ietf-teas-5g-network-slice-application

  The details of this solution is described in
  [I-D.ietf-dmm-tn-aware-mobility].

# Normative references

At least [RFC9543], [I-D.ietf-dmm-udp-tunnel-acaas-extn], [RFC9834], [RFC9889], and NRM should be normative.

Please check the classification of other references and fix as appropriate. Thanks.

[Ballot comment]
# For Chairs/AD: As this is a document covering an architecture owned by another SDO, I wonder whether there was an LS sent to the 3GPP about this doc?

# Leverage Existing RFCs & Consistency

RFC9889 already clarifies the concept of slicing in 3GPP, the concept of TN, relationship between TN slicing and IETF Network Slicing, mapping considerations, realization of TN slicing beyond identification matters, various deployment options for the location of SDP, the attachment circuits, etc.

I suggest that this draft builds on RFC9889 rather than repeating some matters. For example, Sections 2 and 4 can be removed, IMO. rfc9889#section-3 has already all these details.

Moreover, the document should be updated to use a terminology that is consistent with existing RFCs. For example, “end-to-end 5G slice” should be “5G end-to-end slice”, etc.

Cheers,
Med

Request for IETF Last Call review by GENART Completed: Ready with Nits. Reviewer: Linda Dunbar. Sent review to list. Submission of review completed at an earlier date.

The following Last Call announcement was sent out (ends 2026-05-13):

From: The IESG
To: IETF-Announce
CC: dmm-chairs@ietf.org, dmm@ietf.org, draft-ietf-dmm-tn-aware-mobility@ietf.org, satoru.matsushima@gmail.com, tojens.ietf@gmail.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Mobility-aware Transport Network Slicing for 5G) to Informational RFC


The IESG has received a request from the Distributed Mobility Management WG
(dmm) to consider the following document: - 'Mobility-aware Transport Network
Slicing for 5G'
  as Informational RFC

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2026-05-13. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  Network slicing in 5G enables logical networks for communication
  services of multiple 5G customers to be multiplexed over the same
  infrastructure.  While 5G slicing covers logical separation of
  various aspects of 5G infrastructure and services, user's data plane
  packets over the Radio Access Network (RAN) and Core Network (5GC)
  use IP in many segments of an end-to-end 5G slice.  When end-to-end
  slices in a 5G System use network resources, they are mapped to
  corresponding Transport Network (TN) slice(s) which in turn provide
  the bandwidth, latency, isolation, and other criteria required for
  the realization of a 5G slice.

  This document describes mapping of 5G slices to TN slices using UDP
  source port number of the GTP-U bearer when the TN slice provider is
  separated by an "attachment circuit" from the networks in which the
  5G network functions are deployed, for example, 5G functions that are
  distributed across data centers.  The slice mapping defined here is
  supported transparently when a 5G user device moves across 5G
  attachment points and session anchors.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-dmm-tn-aware-mobility/


The following IPR Declarations may be related to this I-D:

  https://datatracker.ietf.org/ipr/4024/
  https://datatracker.ietf.org/ipr/4021/
  https://datatracker.ietf.org/ipr/4022/
  https://datatracker.ietf.org/ipr/4023/

# Internet AD comments for draft-ietf-dmm-tn-aware-mobility-24
CC @ekline

* comment syntax:
  - https://github.com/mnot/ietf-comments/blob/main/format.md

* "Handling Ballot Positions":
  - https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/

## Discuss

## Comments

### __general__

There are several nits that the I-D nits tool in the datatracker has found,
including:

* "IPSec" -> "IPsec"

  (see: https://datatracker.ietf.org/doc/html/rfc4301#section-1.1)

* "Pseudo Wire" should be spelled as pseudowire (no space or hyphen)

### S1

* "slice types list is exemplary" ->

  "slice types list is illustrative" or
  "slice types list serves as an example"

### S3

* I keep wondering if there should be some discussion of the source IP
  address of the GTP-U tunnel somewhere.  Surely no two different GTP-U
  source IPs with the same source port need be mapped to the same slice?

* Also: should there be discussion of the limited UDP port space?  If there
  are (somehow) more than 2^16 TN slices, what does that mean for this
  proposal?  It might be that an applicability statement would rule this
  out of scope.

### S3.3

* The I-D nits tool complained about non-documentation prefixes, and I see
  that 192.9.2.1 is used in Figure 3.  Consider changing this to another
  documentation prefix, perhaps something from TEST-NET-3 (203.0.113.0/24).

## Nits

### S1

* "such as the internet" -> "... Internet"

### S3.2

* "an TN slice" -> "a TN slice"

# Internet AD comments for draft-ietf-dmm-tn-aware-mobility-24
CC @ekline

* comment syntax:
  - https://github.com/mnot/ietf-comments/blob/main/format.md

* "Handling Ballot Positions":
  - https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/

## Discuss

## Comments

### __general__

There are several nits that the I-D nits tool in the datatracker has found,
including:

* "IPSec" -> "IPsec"

  (see: https://datatracker.ietf.org/doc/html/rfc4301#section-1.1)

* "Pseudo Wire" should be spelled as pseudowire (no space or hyphen)

### S1

* "slice types list is exemplary" ->

  "slice types list is illustrative" or
  "slice types list serves as an example"

### S3

* I keep wondering if there should be some discussion of the source IP
  address of the GTP-U tunnel somewhere.  Surely no two different GTP-U
  source IPs with the same source port need be mapped to the same slice?

* Also: should there be discussion of the limited UDP port space?  If there
  are (somehow) more than 2^16 TN slices, what does that mean for this
  proposal?  It might be that an applicability statement would rule this
  out of scope.

### S3.3

* The I-D nits tool complained about non-documentation prefixes, and I see
  that 192.9.2.1 is used in Figure 3.  Consider changing this to another
  documentation prefix, perhaps something from TEST-NET-3 (203.0.113.0/24).

## Nits

### S1

* "such as the internet" -> "... Internet"

### S3.2

* "an TN slice" -> "a TN slice"

Document Shepherd Write-Up for Group Documents:
draft-ietf-dmm-tn-aware-mobility-24

Review updated: 2026-03-02


## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

This document has received multiple reviews and explicit support during WG Last Call.
The WG Last Call ran from 16 Oct 2025 to 30 Oct 2025. We received review comments
(mainly clarifications and editorial nits) as well as explicit statements of support,
and no objections were raised. The chairs therefore judge that the document reflects
WG consensus.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

No significant controversy was observed. The WG Last Call feedback focused on:
clarifying scope (e.g., user-plane focus vs. control-plane discussion),
tightening terminology, and strengthening/clarifying the Security Considerations
around UDP source-port based slice mapping. These items were addressed in
subsequent revisions, and the current version is considered ready to progress.


3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize the areas of conflict in separate email messages to the
  responsible Area Director. (It should be in a separate email because this
  questionnaire is publicly available.)

No.


4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

This is an Informational document describing an approach for mapping 3GPP slices
to Transport Network (TN) slices using existing mechanisms (e.g., GTP-U/UDP) and
existing management models (e.g., ACaaS/YANG references). It does not define a
new on-the-wire protocol requiring interoperability testing. No specific
implementations are claimed or listed in the document.


## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

Yes. The document relates to IETF Network Slicing work (e.g., RFC 9543) and
references TEAS WG drafts for network slice application/realization, and it also
uses terminology and specifications from 3GPP. It additionally references ACaaS
and a YANG data model work item for UDP tunnel support. No formal cross-WG last
call was requested by the DMM chairs; however, review from TEAS/OPS and from
individuals familiar with 3GPP slicing/transport mapping has been helpful and is
welcome.


6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

No formal expert review is required. The document does not define a new MIB,
media type, or URI. It does not include a YANG module.


7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

Not applicable. This document does not contain a YANG module.


8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

Not applicable. The document does not contain formal-language sections.


## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

Yes. The document provides useful, focused guidance for mobility-aware transport
network slicing in 5G deployments where slice mapping is performed using the UDP
source port of GTP-U bearers. It is clearly written for its Informational
purpose, includes Security Considerations (including spoofing/attack mitigation
discussion and operational security mechanisms), and has no IANA actions. There
are minor editorial/idnits items (see Q14) that should be cleaned up, but none
are believed to be blocking.


10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

Security aspects were explicitly reviewed and clarified (e.g., spoofing risk and
need for mechanisms such as ACLs and IPsec / trusted provisioning). No new
protocol elements, registries, MIBs, YANG modules, or media types are defined.
Any remaining issues are editorial in nature.


11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Informational. The document describes an approach and deployment/architecture
guidance for mapping 3GPP slices to TN slices using existing encapsulations and
management models; it does not specify a new standard protocol or new IANA
registries. The Datatracker metadata indicates Intended Status: Informational.


12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

Yes. The WG Last Call announcement reminded participants of BCP 79 obligations.
In the WGLC thread, authors explicitly stated that they were not aware of any
IPR beyond what had already been disclosed. The Datatracker indicates that IPR
disclosures exist for this document.


13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

Yes. The front page lists five authors/editors, which is within the normal
limit. Additional contributors are listed in the “Contributing Authors” section.


14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

The idnits tool reports no errors and no flaws, but does report warnings that
should be addressed prior to publication:
- non-ASCII characters are present in multiple lines;
- one non-RFC6890-compliant IPv4 address appears (likely an example and should
  be replaced with documentation addresses);
- copyright year mismatch warning;
- minor spacing/formatting oddity;
- an “outdated reference” warning for the referenced Internet-Draft version.
These are considered editorial cleanups.


15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

No. The document’s references are intended to be informative; the document does
not rely on normative dependencies for interoperability.


16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

Not applicable. There are no normative references.


17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

Not applicable. There are no normative references.


18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

Not applicable. There are no normative references.


19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.


20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

The IANA Considerations section states that there are no requests for IANA code
point allocations, which is consistent with the document’s content (no new
protocol parameters or registries are defined).


21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

None.

Document Shepherd Write-Up for Group Documents:
draft-ietf-dmm-tn-aware-mobility-24

Review updated: 2026-03-02


## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

This document has received multiple reviews and explicit support during WG Last Call.
The WG Last Call ran from 16 Oct 2025 to 30 Oct 2025. We received review comments
(mainly clarifications and editorial nits) as well as explicit statements of support,
and no objections were raised. The chairs therefore judge that the document reflects
WG consensus.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

No significant controversy was observed. The WG Last Call feedback focused on:
clarifying scope (e.g., user-plane focus vs. control-plane discussion),
tightening terminology, and strengthening/clarifying the Security Considerations
around UDP source-port based slice mapping. These items were addressed in
subsequent revisions, and the current version is considered ready to progress.


3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize the areas of conflict in separate email messages to the
  responsible Area Director. (It should be in a separate email because this
  questionnaire is publicly available.)

No.


4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

This is an Informational document describing an approach for mapping 3GPP slices
to Transport Network (TN) slices using existing mechanisms (e.g., GTP-U/UDP) and
existing management models (e.g., ACaaS/YANG references). It does not define a
new on-the-wire protocol requiring interoperability testing. No specific
implementations are claimed or listed in the document.


## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

Yes. The document relates to IETF Network Slicing work (e.g., RFC 9543) and
references TEAS WG drafts for network slice application/realization, and it also
uses terminology and specifications from 3GPP. It additionally references ACaaS
and a YANG data model work item for UDP tunnel support. No formal cross-WG last
call was requested by the DMM chairs; however, review from TEAS/OPS and from
individuals familiar with 3GPP slicing/transport mapping has been helpful and is
welcome.


6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

No formal expert review is required. The document does not define a new MIB,
media type, or URI. It does not include a YANG module.


7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

Not applicable. This document does not contain a YANG module.


8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

Not applicable. The document does not contain formal-language sections.


## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

Yes. The document provides useful, focused guidance for mobility-aware transport
network slicing in 5G deployments where slice mapping is performed using the UDP
source port of GTP-U bearers. It is clearly written for its Informational
purpose, includes Security Considerations (including spoofing/attack mitigation
discussion and operational security mechanisms), and has no IANA actions. There
are minor editorial/idnits items (see Q14) that should be cleaned up, but none
are believed to be blocking.


10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

Security aspects were explicitly reviewed and clarified (e.g., spoofing risk and
need for mechanisms such as ACLs and IPsec / trusted provisioning). No new
protocol elements, registries, MIBs, YANG modules, or media types are defined.
Any remaining issues are editorial in nature.


11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Informational. The document describes an approach and deployment/architecture
guidance for mapping 3GPP slices to TN slices using existing encapsulations and
management models; it does not specify a new standard protocol or new IANA
registries. The Datatracker metadata indicates Intended Status: Informational.


12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

Yes. The WG Last Call announcement reminded participants of BCP 79 obligations.
In the WGLC thread, authors explicitly stated that they were not aware of any
IPR beyond what had already been disclosed. The Datatracker indicates that IPR
disclosures exist for this document.


13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

Yes. The front page lists five authors/editors, which is within the normal
limit. Additional contributors are listed in the “Contributing Authors” section.


14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

The idnits tool reports no errors and no flaws, but does report warnings that
should be addressed prior to publication:
- non-ASCII characters are present in multiple lines;
- one non-RFC6890-compliant IPv4 address appears (likely an example and should
  be replaced with documentation addresses);
- copyright year mismatch warning;
- minor spacing/formatting oddity;
- an “outdated reference” warning for the referenced Internet-Draft version.
These are considered editorial cleanups.


15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

No. The document’s references are intended to be informative; the document does
not rely on normative dependencies for interoperability.


16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

Not applicable. There are no normative references.


17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

Not applicable. There are no normative references.


18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

Not applicable. There are no normative references.


19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.


20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

The IANA Considerations section states that there are no requests for IANA code
point allocations, which is consistent with the document’s content (no new
protocol parameters or registries are defined).


21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

None.