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

[Krzysztof Szarkowicz <[e-mail]>]

Adrian, Med,

Returning to this. I’ve seen many design cases with SPs, where the network is designed physically in very structured manner. Also, I’ve seen some analysis done by couple of SPs, that as the result of this very structured network design, after making internal analysis, they don’t really see the difference between path placement done using IGP metric, and path placement done using delay metric. Hence, even introducing some flex-algos (TE meshes) with different metric optimization is questionable here (as the resulting paths are the same).

To realize services with SLO commitments, these SPs today extensively use admission control at the edge (some times even relatively complex admission control schemes at the edge). But, they don’t use anything specific (TE, Flex-Algo) in the transport, apart from mentioned admission control at the edge (ingress/egress policers/shapers), basic QoS on transit, network capacity planning, and timely capacity upgrades, where needed.

Does this approach could be considered as well as some way of ’network resource partitioning’ mentioned in the draft?

Cheers,
Krzysztof


> On 2022 -Mar-28, at 12:26, Krzysztof Szarkowicz <[e-mail] <mailto:[e-mail]>> wrote:
> 
> OK,
> 
> If a realization example of network partition is flex-algo + admission control, then I am fine.
> 
> Thanks,
> Krzysztof
> 
> 
>> On 2022 -Mar-28, at 11:36, <[e-mail] <mailto:[e-mail]>> <[e-mail] <mailto:[e-mail]>> wrote:
>> 
>> Re-,
>>  
>> Manipulating flavors of flex-algos (+ appropriate admission control) is indeed a way to partition a network.
>>  
>> Cheers,
>> Med
>>  
>> De : Krzysztof Szarkowicz <[e-mail] <mailto:[e-mail]>> 
>> Envoyé : lundi 28 mars 2022 11:31
>> À : BOUCADAIR Mohamed INNOV/NET <[e-mail] <mailto:[e-mail]>>; [e-mail] <mailto:[e-mail]>
>> Cc : [e-mail] <mailto:[e-mail]>
>> Objet : Re: [Teas] [E] Re: Slicing Framework Open issue #1 : Service != Realization
>>  
>> Hi Med, Adrian,
>>  
>> I still see the partition as realization, thus should be left to the docs/drafts describing the realization, rather than be mandated in framework doc. 
>>  
>> Section 7.2. says:
>>  
>> For example, traffic separation between different IETF Network Slices may be achieved using VPN technologies, such as L3VPN, L2VPN, EVPN, etc. Interference avoidance may be achieved by network capacity planning, allocating dedicated network resources, traffic policing or shaping, prioritizing in using shared network resources, etc. 
>>  
>> ‘Allocating dedicated network resources’, which is my understanding of network partition, is one (and not the only one) of many tools that can be used for realization. 
>>  
>> But, if you are saying, that from, realization perspective for example I can call I partitioned my network by creating two flex-algos, or two sets of TE tunnels (one optimized for latency, another optimized for high capacity links, as an example), then definition of partition is very open, indeed. 
>>  
>> Thanks,
>> Krzysztof
>>  
>> 
>> 
>> On 2022 -Mar-28, at 08:20, <[e-mail] <mailto:[e-mail]>> <[e-mail] <mailto:[e-mail]>> wrote:
>>  
>> 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] <mailto:[e-mail]>> De la part de Adrian Farrel
>> Envoyé : vendredi 25 mars 2022 22:22
>> À : 'Krzysztof Szarkowicz' <[e-mail] <mailto:[e-mail]>>
>> Cc : [e-mail] <mailto:[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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