Re: [Teas] [E] Re: Slicing Framework Open issue #1 : Service != Realization

[[e-mail]]

Hi Adrian, al,

I think that it is safe to say that partitioning is always needed to realize a slice service. In reference to -10, I even tend to suggest this change:

==
OLD:
An IETF Network Slice is a slice of a network that uses
   IETF technology.

NEW:

An IETF Network Slice is a partition of a network that is provided using

   IETF technologies.

==

However, that partition does not need to involve only node resources that are partitioned (e.g., some nodes of a partition may exclusively belong to one single slice) or that partition resources are fully isolated. For example, it is completely fine that some form for resource preemption is allowed between slices that belong to the same customer or those engineered for internal use of an operator. I suggest to clarify this in the text by making this change:

====
OLD:

   Network slicing provides the ability to partition a physical network

   into multiple isolated logical networks of varying sizes, structures,

                 ^^^^^^^^

   and functions so that each slice can be dedicated to specific

   services or customers.

NEW:

   Network slicing provides the ability to partition a physical network

   into multiple logical networks of varying sizes, structures,

   and functions so that each slice can be dedicated to specific

   services or customers. The support of resource preemption between

                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   IETF network slices is deployment specific.
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
=====

Please note that this proposed change is consistent with the definition of “isolation” in the draft:

==

   Isolation:  As described in Section 7<https://datatracker.ietf.org/doc/html/draft-ietf-teas-ietf-network-slices-10.txt#section-7>, a customer may request that

      its traffic within its IETF Network Slice service is isolated from

      the effects of other network services supported by the same

      provider.

===

and also this text:

==

   An IETF Network Slice could span multiple technologies and multiple

   administrative domains.  Depending on the IETF Network Slice

   customer's requirements, an IETF Network Slice could be isolated from

   other, often concurrent IETF Network Slices in terms of data, control

   and management planes.

==

Thank you.

Cheers,
Med

De : Teas <[e-mail]> De la part de Adrian Farrel
Envoyé : vendredi 25 mars 2022 22:22
À : 'Krzysztof Szarkowicz' <[e-mail]>
Cc : [e-mail]
Objet : Re: [Teas] [E] Re: Slicing Framework Open issue #1 : Service != Realization

Hi Krzysztof,

I think you might have something here, but it is confused by a side point.

“might be entire network is single partition” is not a contradiction with “partitioning the network resources.” True, it is at the extreme end of the spectrum, but one is a special case of many.

Now, the BIG question for network slicing is whether the network resources are partitioned at all. If they are counted in any way (including in a central controller) in order to ensure that the traffic can meet the SLOs, then the resources *are* partitioned. It is only if the service delivery is best effort, allowing for congestion and drops, that we can say that the resources are not partitioned.

Or, in another view, if traffic for a particular service is steered onto particular links in order to meet SLOs (for example, latency), then the resources have been partitioned.

So, while I agree that partitioning is strongly tied to realization, I wonder whether it is possible to have a network slice (note “slice”, not “slice service”) without it.

My concern is that we end up with a definition of network slice that is so far removed from realization that it becomes “a slice is what an operator does to their network to deliver a slice service” which, I think, doesn’t tell us what a slice is.

Cheers,
Adrian

From: Krzysztof Szarkowicz <[e-mail]<mailto:[e-mail]>>
Sent: 25 March 2022 17:57
To: Adrian Farrel <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]>
Subject: Re: [Teas] [E] Re: Slicing Framework Open issue #1 : Service != Realization

Hi,

I have only one comment, regarding below:

  the "IETF Network
  Slice" which is the realization of the service in the provider's
  network achieved by partitioning network resources and by
  applying certain tools and techniques within the network (see
  Section 3.1).

‘Achieved by partitioning network resources’ is some specific relation option, which might (or might not) be used in particular realization (depending how the slice is realized, might be entire network is single partition). Hence, it should rather be omitted here, as it should be agnostic to to the actual realization. Thus, I would change it to:

  the "IETF Network
  Slice" which is the realization of the service in the provider's
  network achieved by
  applying certain tools and techniques within the network (see
  Section 3.1).


Regards,
Krzysztof


On 2022 -Mar-25, at 12:48, Jalil, Luay <luay.jalil=[e-mail]<mailto:luay.jalil=[e-mail]>> wrote:

+1

Regards,
Luay


On Fri, Mar 25, 2022 at 10:49 AM LUIS MIGUEL CONTRERAS MURILLO <[e-mail]<mailto:[e-mail]>> wrote:
Hi all,

Agree, the proposed change is ok.

Best regards

Luis

-----Mensaje original-----
De: Teas <[e-mail]<mailto:[e-mail]>> En nombre de Joel M. Halpern
Enviado el: viernes, 25 de marzo de 2022 10:30
Para: [e-mail]<mailto:[e-mail]>
Asunto: Re: [Teas] Slicing Framework Open issue #1 : Service != Realization

Works for me.
Yours,
Joel

On 3/25/2022 5:17 AM, Adrian Farrel wrote:
> Hi,
>
> First in a series of emails to resolve the open issues mentioned
> during the TEAS meeting.
>
> We have, for the longest time, suffered from a blurring between the
> service provided to the customer, and how that service is engineered in the network.
> This leads us to talk about VPNs in a way where sometimes a VPN is
> what the customer gets and sometimes it is what the operator
> engineers. A good example is the term "MPLS VPN" as though the
> customer cares whether the VPN is provided using MPLS technology.
>
> We have, to some extent, clarifies this with recent YANG "Customer
> Service Models" that describe the service offered to the customer, but
> do not constrain the provider's choice of implementation technology or options.
>
> As the discussion of IETF Network Slices continues, I have repeatedly
> seen some blurring between the topics of the "IETF Network Slice
> Service" and the "IETF Network Slice." It seems to me that this mixing
> of concepts will continue as future readers pick up the document.
>
> Although I have tried to use the two terms clearly and distinctly, the
> document is missing a clear statement to disambiguate the two.
>
> Section 3 provides the definitions of the two terms at some length
> using subsections. The clarification would get lost if it was placed
> at the bottom of the section after the subsections, so I propose to
> include some text near the top of section as follows.
>
> OLD
>     IETF Network Slices are created to meet specific requirements,
>     typically expressed as bandwidth, latency, latency variation, and
>     other desired or required characteristics.  Creation of an IETF
>     Network Slice is initiated by a management system or other
>     application used to specify network-related conditions for particular
>     traffic flows in response to an actual or logical IETF Network Slice
>     service request.
>
>     Once created, these slices can be monitored, modified, deleted, and
>     otherwise managed.
>
>     Applications and components will be able to use these IETF Network
>     Slices to move packets between the specified end-points of the
>     service in accordance with specified characteristics.
> NEW
>     IETF Network Slices are created to meet specific requirements,
>     typically expressed as bandwidth, latency, latency variation, and
>     other desired or required characteristics.  Creation of an IETF
>     Network Slice is initiated by a management system or other
>     application used to specify network-related conditions for particular
>     traffic flows in response to an actual or logical IETF Network Slice
>     service request.
>
>     Once created, these slices can be monitored, modified, deleted, and
>     otherwise managed.
>
>     Applications and components will be able to use these IETF Network
>     Slices to move packets between the specified end-points of the
>     service in accordance with specified characteristics.
>
>     A clear distinction should be made between the "IETF Network
>     Slice service" which is the function delivered to the customer
>     (see Section 3.2) and which is agnostic to the technologies and
>     Mechanisms used by the service provider, and the "IETF Network
>     Slice" which is the realization of the service in the provider's
>     network achieved by partitioning network resources and by
>     applying certain tools and techniques within the network (see
>     Section 3.1).
> END
>
> Any objections?
>
> Thanks,
> Adrian
>
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