[Teas] Last-gasp review of draft-ietf-teas-5g-ns-ip-mpls-11

[Adrian Farrel <[e-mail]>]

Hi,

 

Here (finally) is my additional review of this draft. Sorry to have 

taken a few additional days.

 

Other than the comments (arising from Jie's review), I have only 

found a small points and a couple of nits.

 

Not sure whether I should have spotted these in previous reviews. If so,

sorry.

 

Thanks for all the work.

 

Cheers,

Adrian

 

===

 

idnits shows " Unused Reference: 'TR-GSTR-TN5G' "

 

---

 

Section 2, having said the document makes use of the terms defined in

RFC 9543, proceeds to provide a new definition of "customer" and 

"provider". I wonder whether those new definitions are necessary, and 

if they are I think great care is needed to achieve disambiguation.

 

---

 

In Section 3.1, piping ("|") is used to indicated quoted text from 3GGPP

documents. That's good.

But: 

- It is probably de trop to use quotation marks as well.

- It appears as though the reference is part of the quote.

 

---

 

3.2.1

 

Ditto the use of | and "

 

---

 

3.2.2

 

I don't object to one word of the text in 3.2.2. I do find it peculiar

that, while 3.2.1 is nicely quoted from 3GPP documentation, the text in

this section is longer and un-cited.

 

I should imagine that the paragraph...

    The objective of Transport Network Slicing is

...should be founded in a 3GPP definition.

 

While the first half of the paragraph...

   Transport Network Slicing provides various degrees of sharing of

   resources between slices

...presumably stems from 9543

 

The rest of the text is explanatory in the context of this document (and

maybe should say so).

 

---

 

Slice scopes and SDP locations.

 

It is all really confusing to me, and I do not arrive at anything other

than contradictions from the text :-(

 

Figure 1 shows the TN slice and also shows the type 3 and type 4 SDP

locations.

 

But, an SDP is the point at which the slice service begins or ends. It

is the edge of the slice.

 

Either:

- You are saying that a transport slice does not map perfectly to an

  IETF slice

Or:

- There is something wrong with this and the text in 3.4.2.

 

I don't think any of this changes any of the technical details or

practicalities of the solutions described. It just that the description

seems plain wrong.

 

For example, where you talk about mapping service parameters: where

is that mapping performed? The question, I suppose is, are you 

constructing a TN slice that encompasses network resources that are

both IETF and non-IETF. In that case, the service parameters are

mapped at the edge of the TN slice, and then they are mapped again

at the network boundary at the start of the IETF technology.

 

If your intention is that the TN slice is constructed from elements of

the customer domain (possibly non-IETF) and the provider domain (IETF),

that would be fine, but I think the TN slice end points are still the 

SDPs.

 

If, conversely, you are saying that the TN slice is a composite of

customer domain slice and IETF slice, then you have the SDPs correctly

placed, but you have not made this composite clear.

 

It does not help that 3.4.2 goes on to say:

   The concept of distributed PE (Section 3.3.4) assimilates CE-based

   SDPs defined in Section 5.2 of [RFC9543] (i.e., Types 1 and 2) as SDP

   Type 3 or 4 in this document.

 

The problem is not with the text, but with the fact that your Figure 6

shows the TN slice extending to the CEs in a model where the CEs are

distinct from the PEs. (To me it seems that you are doing types 1 and 2

in this document with the case of distributed PE assimilating types 3

and 4.)

 

I start to run into some of this again in Section 4. For example, in 4.1

   In this option, the RFC 9543 Network Slice, fulfilling connectivity

   requirements between NFs that belong to a 5G slice, is represented at

   an SDP by a VLAN ID (or double VLAN IDs, commonly known as QinQ), as

   depicted in Figure 12.

That suggests to me that the model in your head is that the VLAN ID is 

indicative of either:

- onto which IETF slice the SDP should place the traffic (the traffic 

  is at that stage not yet sliced only marked for slicing)

or:

- on which IETF slice the traffic is flowing (the traffic has already

  been sliced and the SDP is actually at the end of the TN slice).

 

To complete my whining about this, 4.2 shows the "tunnels representing

slices" as extending all the way to the NFs (CEs not marked). Surely,

in that case, the SDP is at the end of the tunnel?

 

 

I'd be quite happy with either or any approach. I just want the 

description to match.

 

---

 

3.6

 

   At the time of writing (2024), Section 6.1.2 of [NG.113] specifies

 

Well...

NG.113 is a dated reference. Doesn't that mean that you can simply say

 

   Section 6.1.2 of [NG.113] specifies

 

While it is true that 3GGP's "5GS Roaming Guidelines" may change over

time. The referenced Version 4 dated 2021 will not change.

 

---

 

3.7

 

s/of [RFC9522])./of [RFC9522]./

 

---

 

Figure 11

 

Is there an arrow head missing from the left hand end of the line within

the right hand P node?

 

From: [e-mail] <[e-mail]> 
Sent: 24 September 2024 09:47
To: Adrian Farrel <[e-mail]>; Vishnu Pavan Beeram
<[e-mail]>; TEAS WG <[e-mail]>
Cc: TEAS WG Chairs <[e-mail]>
Subject: [Teas] Re: Responses for LS on "Realization of Network Slices for
5G Networks Using Current IP/MPLS Technologies"

 

Hi Adrian,

 

Deal! Thank you for your efforts. 

 

I also hope that Jie can check and let us know if we missed any of his
comments.

 

Cheers,

Med

 

De : Adrian Farrel <[e-mail]> 
Envoyé : mardi 24 septembre 2024 10:22
À : BOUCADAIR Mohamed INNOV/NET <[e-mail]>; Vishnu Pavan
Beeram <[e-mail]>; TEAS WG <[e-mail]>
Cc : TEAS WG Chairs <[e-mail]>
Objet : [Teas] Re: Responses for LS on "Realization of Network Slices for 5G
Networks Using Current IP/MPLS Technologies"

 

Thanks to all for the hard work on this document. It is definitely getting
much better (and shorter) which is a good thing for all of us. 

  

There does seem to have been a lot of changes sine the first last call, and
even since the second one. It also looks (to me) that there are a few of
Jie's comments still unresolved. 

  

I plan to scan the doc tonight and I'll try to suggest resolutions for the
points that look to be still open. 

  

A 

On 24/09/2024 10:05 CEST [e-mail]
<mailto:[e-mail]>  wrote: 

  

  

Hi Pavan, all, 

 

FWIW, the changes are now implemented in the public version together with
additional follow-up comments from Jie:
https://datatracker.ietf.org/doc/draft-ietf-teas-5g-ns-ip-mpls/11/. 

 

Cheers,

Med

 

De : BOUCADAIR Mohamed INNOV/NET 
Envoyé : lundi 9 septembre 2024 15:34
À : 'Vishnu Pavan Beeram' <[e-mail]
<mailto:[e-mail]> >; TEAS WG <[e-mail]
<mailto:[e-mail]> >
Cc : TEAS WG Chairs <[e-mail] <mailto:[e-mail]> >
Objet : RE: [Teas] Responses for LS on "Realization of Network Slices for 5G
Networks Using Current IP/MPLS Technologies"

 

Hi Pavan, all,

 

Thanks for sharing your conclusions. 

 

Looks good to me. Fixed right now the ref nits:
https://github.com/boucadair/5g-slice-realization/commit/3c11d6e6baa2f50a10a
95904c8abb29753e91034. These nits can be queues for a next iteration when we
will have more comments, but we can release a new version if you prefer so.
Thanks.

 

Cheers,

Med

 

De : Vishnu Pavan Beeram <[e-mail]
<mailto:[e-mail]> > 
Envoyé : lundi 9 septembre 2024 10:04
À : TEAS WG <[e-mail] <mailto:[e-mail]> >
Cc : TEAS WG Chairs <[e-mail] <mailto:[e-mail]> >
Objet : [Teas] Responses for LS on "Realization of Network Slices for 5G
Networks Using Current IP/MPLS Technologies"

 

WG,

 

We sent a liaison statement [1] in June to multiple 3GPP groups seeking
feedback on our WG draft that discusses “Realization of Network Slices for
5G Networks Using Current IP/MPLS Technologies” [2]. 

We have received replies from 3GPP-TSGSA-SA2 [3], 3GPP-TSG-SA-WG5 [4] and
O3GPPTSGRAN3 [5]. We request the WG to review the feedback and chime in with
your thoughts/opinions.

 

The following is our (chairs’) interpretation of the feedback that was
received.

 

*	3GPP-TSGSA-SA2:

*	Remove Appendices B.1 and B.2 and just have a reference to TS-23.501
*	No endorsement of the “Hand-off” options discussed in Section 4 and
the QoS Mapping Realization Models in Section 5

*	This need not warrant any changes to Sections 4 and 5. We need to
ensure that the language used in these two sections doesn’t imply any
endorsement by 3GPP.

*	3GPP-TSG-SA-WG5:

*	Fix the reference to 3GPP TS 28.530

*	O3GPPTSGRAN3:

*	Inaccuracies exist in Appendix B.3. Suggest adding references to
TS-38.300 and TS-38.401

*	In other words, this is a recommendation to remove Appendix B.3.

 

Based on the above, our recommendation is to remove Appendix B (including
the Transport Network specific sub-section) and add the suggested references
in the Introduction. The authors have published a new revision (rev 10) with
Appendix B removed. Please review the latest changes and let us know if
there are any comments/concerns.

 

Regards,

-Pavan and Oscar 

 

[1]  <https://datatracker.ietf.org/liaison/1931/>
https://datatracker.ietf.org/liaison/1931/

[2]  <https://datatracker.ietf.org/doc/html/draft-ietf-teas-5g-ns-ip-mpls>
https://datatracker.ietf.org/doc/html/draft-ietf-teas-5g-ns-ip-mpls

[3]  <https://datatracker.ietf.org/liaison/1955/>
https://datatracker.ietf.org/liaison/1955/

[4]  <https://datatracker.ietf.org/liaison/1956/>
https://datatracker.ietf.org/liaison/1956/

[5]  <https://datatracker.ietf.org/liaison/1957/>
https://datatracker.ietf.org/liaison/1957/

 

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