Re: [Teas] I-D Action: draft-wd-teas-ietf-network-slice-nbi-yang-05.txt

Hi,

Let me chime in to provide some feedback on the draft-wd-teas-ietf-network-slice-nbi-yang, from the 5G slicing perspective. There are couple of comments, I would like to provide.

1. Single 5G slice can incorporate multiple traffic classes, denoted by 3GPP as 5QI (5G QoS Identifier), and represented at the transport level with different DSCP values in GTP packets. Obviously, these different traffic classes within single slice have different SLO requirements, and I don't see in the proposed NBI any ways to specify SLO per traffic class (as for example available in L3SM or L2SM models)

2. 5G slice might specify SLO requirements per connections, for example:

    UPF-1 ---> CU-1: guaranteed BW: 1G, maximum BW 2G
    UPF-1 ---> CU-2: guaranteed BW: 1.5G, maximum BW 2G
    UPF-1 ---> CU-3: guaranteed BW: 1.5G, maximum BW 3G

And additionally per groups of connections, i.e.:

   UPF-1 ---> <CU-1, CU-2, CU-3>: guaranteed BW: 4G, maximum BW 4G

I am not sure, how the above construct can be mapped to the proposed NBI (don’t even see the notation of both ‘guaranteed/max’, or CIR/PIR in MEF language, bandwidth).

3. Operators might have different strategies, how to implement traffic separation between the 5G slices at the transport level. As an example, operator A might decide to put N3 interfaces of one 5G slice in one L3VPN, while to put N6 interfaces on the same 5G slice in another L3VPN. On the other hand, operator B might decide to put both N3 and N6 interfaces of some 5G slice in common L3VPN. Each strategy has some disadvantage/advantage, but both strategies are valid. Similar, the control plane (i.e. A1, E2, O1 interfaces ), operators might decide that some 5G slices shares L3VPN for control plane, while some other 5G slices use separate L3VPN for control plane. I don’t see anything in the NBI to address this.

4. NBI attempts to be ‘abstract and technology-agnostic’, while when talking about mapping 5G slices to transport, folks are talking about L3VPNs, DCSP/Exp values, etc., which will require porting of significant part of current L3SM/L2SM models into proposed NBI model in order to make it applicable for 5G slicing.

All if this makes me believe, that augmenting of existing L3SM/L2SM models is better strategy for NBI for 5G slicing.

Best regards,
Krzysztof Szarkowicz

> On 2021 -Sep-26, at 11:13, Wubo (lana) <lana.wubo@huawei.com> wrote:
> 
> Hi all,
> 
> Revision-05 adds a new section, sec 4. Background on IETF Network Slice Service Modeling. We give an analysis on why a new network slice YANG model is needed instead of reusing LxSM or augmenting ACTN VN.
> 
> Thanks,
> Bo
> 
> -----邮件原件-----
> 发件人: Teas [mailto:teas-bounces@ietf.org] 代表 internet-drafts@ietf.org
> 发送时间: 2021年9月26日 16:42
> 收件人: i-d-announce@ietf.org
> 抄送: teas@ietf.org
> 主题: [Teas] I-D Action: draft-wd-teas-ietf-network-slice-nbi-yang-05.txt
> 
> 
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Traffic Engineering Architecture and Signaling WG of the IETF.
> 
>        Title           : IETF Network Slice Service YANG Model
>        Authors         : Bo Wu
>                          Dhruv Dhody
>                          Reza Rokui
>                          Tarek Saad
>                          Liuyan Han
>                          Luis Miguel Contreras
> 	Filename        : draft-wd-teas-ietf-network-slice-nbi-yang-05.txt
> 	Pages           : 49
> 	Date            : 2021-09-26
> 
> Abstract:
>   This document provides a YANG data model for the IETF Network Slice
>   service.  The model can be used by a IETF Network Slice Customer to
>   manage IETF Network Slice from an IETF Network Slice Controller
>   (NSC).
> 
> 
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-wd-teas-ietf-network-slice-nbi-yang/
> 
> There is also an htmlized version available at:
> https://datatracker.ietf.org/doc/html/draft-wd-teas-ietf-network-slice-nbi-yang-05
> 
> A diff from the previous version is available at:
> https://www.ietf.org/rfcdiff?url2=draft-wd-teas-ietf-network-slice-nbi-yang-05
> 
> 
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
> 
> 
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