Re: [Teas] New term for the underlay construct used for slice realization

["Dongjie (Jimmy)" <[e-mail]>]

Hi Greg,

Please see some replies inline:

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Sent: Wednesday, August 11, 2021 5:13 AM
To: Lizhenbin <[e-mail]>
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Subject: Re: [Teas] New term for the underlay construct used for slice realization


Hi Robin,

thank you for starting the discussion. Please find my notes in-lined below under the GIM>> tag.



Regards,

Greg Mirsky



Sr. Standardization Expert
预研标准部/有线研究院/有线产品经营部 Standard Preresearch Dept./Wireline Product R&D Institute/Wireline Product Operation Division


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Sender: Lizhenbin
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Date: 2021/08/10 08:21
Subject: [Teas] New term for the underlay construct used for slice realization
Hi Folks,

On the TEAS meeting in IETF 111, it was discussed that a common "new term" will need to be proposed for the underlay construct used for slice realization.

There have been several related terminologies:

1.    VTN (Virtual Transport Network)

In the early days of network slicing discussion in IETF, it was suggested that the technology in IETF should be neutral and not bound to network slicing only. Following this approach, the term VTN is defined in the enhanced VPN draft already adopted and progressing in TEAS. It is expected that the VTNs with guaranteed resources can also be applicable to services other than network slices. The VPN+ architecture allows flexible mapping (including 1:1, N:1 and 1:N mapping) between the overlay VPN services and the underlay VTNs. Since VTN is a generic term, in the context of network slicing we may still need a specialized term.

GIM>> I think that when at IETF we refer to a network as transport, that implies that the one of defined at IETF transport protocols, e.g., TCP, UDP, SCTP, or DCCP, is used. As I understand the VPN+ proposal, that is not the case. If that is correct, then before using VTN, need to define what is the interpretation of "transport".

[Jie] Please see my replies to John about the term VTN. Here “transport” was used to refer to the underlay network in contrast to the overlay virtual networks. Another possible interpretation of VTN could be “Virtual TE Network”.

Best regards,

Jie

2.    Slice Aggregate

It is claimed that the scope of Slice Aggregate is tied to the scope of IETF network slices. This term implies an aggregation of one or more IETF network slices into an aggregate construct, so that only a 1:1 and N:1 mapping of network slice service to underlay construct can be achieved. However, if this is a mapping of network slice traffic streams to underlay constructs, then it may be possible to map network slice services to the underlay construct as 1:1, N:1 and 1:N, but the name may be confusing because it is not the slices that are aggregated.


GIM>> I think that it is beneficial not to use "slice" in the term that identifies an object in the underlay network that provides service to a slice. See more on that below.


With this background in mind, now we can discuss how to define the new term. Here are some points for the WG to consider:

1.     Should the underlay construct for network slice realization bound to network slice services? That is, is the underlay construct only for use in network slicing, or should it be generalized for more possible uses?

GIM>> Yes to the latter (that is why calling it "Slice Aggregate" might be confusing)


2.    If the answer to question 1 is YES, should it reflect the following characteristics?

GIM>> Strictly speaking, I don't see how an answer to one of questions listed in #1 can be "No". But that's OK.

a.    It is about the underlay
b.    It is about the partitioned resources used to deliver the network slice services
c.    It allows the 1:1, N:1, and 1:N mapping models between the network slice services and the underlay construct. The 1:1 and N:1 mapping may be straightforward. Does it also make sense to divide the elements or traffic flows in a single network slice service to carry them in different underlay constructs?

GIM>> Yes to all.


Lastly, here are some candidates of the "new term":

Option 1: The network slice service is called "overlay slice", then the underlay construct is called "underlay slice".

Option 2: The network slice service is called "service slice", then the underlay construct is called "resource slice".

GIM>> I think that the term used for underlay resources delegated to a particular slice should not refer to "slice".


Your opinion about these candidates are much appreciated. You may also propose other new term if it complies with the above two points.



Best Regards,
Robin

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