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

[John E Drake <[e-mail]>]

Hi,

Comments inline.

Yours Irrespectively,

John


Juniper Business Use Only

> -----Original Message-----
> From: Teas <[e-mail]> On Behalf Of Lizhenbin
> Sent: Tuesday, August 10, 2021 11:21 AM
> To: [e-mail]
> Subject: [Teas] New term for the underlay construct used for slice realization
> 
> [External Email. Be cautious of content]
> 
> 
> 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.

[JD]  I never liked this term because what it is describing is real not virtual and because the IETF does not build transport networks.  I.e., what it is describing is a subset of the underlay network topology with partitioned resources. 

> 
> 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.

[JD]  This term never resonated with me because it is slice specific and because, as Adrian pointed out, it's actually used to describe multiple, incompatible ideas.  

> 
> 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?

[JD] Absolutely yes 

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

[JD]  Yes to all of the above.  Please see:    https://datatracker.ietf.org/doc/html/draft-drake-bess-enhanced-vpn-06
> 
> 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".

[JD]  I don't think we need another term for what we are already calling an 'IETF Network Slice Service'.  Adrian and I are considering the term
'resource partition' to describe the partitioning of underlay network resources in support of various overlay services such as IETF Network Slice Services.
This is congruent with the ideas expressed in:  https://datatracker.ietf.org/doc/html/draft-ietf-spring-resource-aware-segments-03.  What this allows
one to build is an 'partitioned underlay network topology'.  

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

[JD]  I think you have exceeded your remit. 

> 
> 
> 
> Best Regards,
> Robin
> 
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