Subject: Re: [Teas-ns-dt] Comment to definitions draft in today's call -- logical vs abstract vs virtual

From: Zhenghaomian <[email-masked]>
Date: Fri, 6 Mar 2020 02:18:15 +0000

Hi, Luis, Eric, Sergio, All,

Firstly thank you for mentioning Dali and Escher. I never knew them (and their works), but a quick search make be better understanding Europe art history and networking ‘virtualization’☺

I am writing as an optical people, who is a part of the slice but not the majority. In optical specifications we use term ‘virtual’ and ‘abstract’ more often than ‘logical’ (specified by RFC7926 as well), with following interpretations.
The term ‘virtual’ is used together with ‘physical’. A typical example is when we use an old phone, we need to press the button to input the text, but now when you use a smart phone, you touch on the screen and type with a ‘virtual keyboard’. The difference is a ‘physical feel’ to our body. Consider the application on the transport slices, if the consumer/provider is operating from GUI, then it’s a kind of virtual. For network operation the virtualization is usually lossless, i.e., when a controller virtualize something (from its SBI to its NBI), it should be capable to bring it back (from its NBI to its SBI). It’s just providing the equivalent functionality without physical feedback, and has nothing to do with ‘cheating’ or ‘lying’ unless the functionality is not delivered.
The term ‘abstract’ is used together with ‘raw’ and emphasized with data processing. When we manage the network we can directly obtain the raw data, but for some specific reason or application we process and wrap up again to form an ‘abstract’ data. According to RFC7926, the abstraction is driven by policy to select a part of information. In this way, abstract is usually ‘lossy’ instead of ‘lossless’ by using only subset of data. Regarding the current TS definition, the SLO MUST be a kind of ‘abstract’ instead of ‘raw’, as many of the objective functions are something computed rather than directly obtained from the network.

For ‘logical’, it looks to me that Eric is using it together with ‘real’. I am not sure if there is formal text in existing RFCs about the meaning, but it’s not formally used in optical.

I am also not native English speaker so the understanding on vocabulary may not be accurate enough. I just wish the definition of transport slice can be matched with the imagination in my head, the top features are: ‘not physical’ – virtual, and ‘abstract’ based on SLO.

My 2 cents,
Haomian

发件人: Teas-ns-dt [mailto:[email-masked]] 代表 LUIS MIGUEL CONTRERAS MURILLO
发送时间: 2020年3月6日 3:02
收件人: Eric Gray <[email-masked]>; Belotti, Sergio (Nokia - IT/Vimercate) <[email-masked]>; [email-masked]
主题: Re: [Teas-ns-dt] Comment to definitions draft in today's call -- logical vs abstract vs virtual

Hi Eric,

I love Dali, and also Escher.

I think that in terms of complexity we can compare some existing solutions and designs with their ability to make complex things look easy, but be sure that those do not have the same beauty or finezza ☺.

Best regards

Luis

De: Eric Gray <[email-masked]<mailto:[email-masked]>>
Enviado el: jueves, 5 de marzo de 2020 19:06
Para: Belotti, Sergio (Nokia - IT/Vimercate) <[email-masked]<mailto:[email-masked]>>; LUIS MIGUEL CONTRERAS MURILLO <[email-masked]<mailto:[email-masked]>>; [email-masked]<mailto:[email-masked]>
Asunto: RE: [Teas-ns-dt] Comment to definitions draft in today's call -- logical vs abstract vs virtual

Yes, the separation of virtual and real is a big part of the “freight” that “virtual” carries.

At a “Disruptive Technologies” class given at AT&T decades ago, the teacher told us “Whenever you hear ‘virtual’ – you should interpret this as ‘I am lying.’”

This is only a perception thing, but that does not mean it is not just as real as if it were real.  In way too many cases, virtual is used explicitly to distinguish it from reality.  For example, “virtual reality” is pretty much never considered to include “real reality.”  😊

I tend to prefer “logical” in this context, over either “virtual” or “abstract” – in no small part because “abstract” also has “freight.” “Abstract” is often considered to be similar in meaning to “surreal” – which is very unlikely to be what we mean by an “abstract topology” for example.  I cannot wrap my head around the notion of a network designed (for instance) by either Salvador Dali, or M.C. Escher.

But these are minor preferences.  With the exception of context-related cases (where we need to use the terminology that fits best in a given context), I think we should try to be consistent and I am fine with any term everyone can live with.

From: Teas-ns-dt <[email-masked]<mailto:[email-masked]>> On Behalf Of Belotti, Sergio (Nokia - IT/Vimercate)
Sent: Thursday, March 5, 2020 12:35 PM
To: LUIS MIGUEL CONTRERAS MURILLO <[email-masked]<mailto:[email-masked]>>; [email-masked]<mailto:[email-masked]>
Subject: Re: [Teas-ns-dt] Comment to definitions draft in today's call -- logical vs abstract vs virtual

I think that logical (or even abstract) is more comprehensive since virtual reminds to some kind of virtualization of the underlying resources, but a slice could naturally involve (dedicated) physical resources. So that is why I'm inclined to use logical as a more generic term.

Virtualization has nothing to do with “select” only physical resources but instead is related to select underlying resources (physical or abstract) in the prospective to a particular customer, application or service.
If this was your problem with virtual , it is not a problem.

Regards
SErgio

From: Teas-ns-dt <[email-masked]<mailto:[email-masked]>> On Behalf Of LUIS MIGUEL CONTRERAS MURILLO
Sent: Thursday, March 5, 2020 6:12 PM
To: [email-masked]<mailto:[email-masked]>
Subject: [Teas-ns-dt] Comment to definitions draft in today's call -- logical vs abstract vs virtual

Hi all,

Apologies, I experienced problems in the call today, not being able for me to speak up (even I lost part of the discussions, apologies again).

I wrote my preference in the chat, I think you couldn’t echoed.

So respect to the discussion of preference for logical  vs abstract vs virtual, I think that logical (or even abstract) is more comprehensive since virtual reminds to some kind of virtualization of the underlying resources, but a slice could naturally involve (dedicated) physical resources. So that is why I'm inclined to use logical as a more generic term.

Note that in the operators’ vocabulary today “virtual” has further connotations (exceeding the transport part), so can be an overloaded term in some end-to-end scenarios.

Best regards

Luis

__________________________________
Luis M. Contreras

Technology and Planning
Transport, IP and Interconnection Networks
Telefónica I+D / Global CTIO unit / Telefónica

Distrito Telefónica, Edificio Sur 3, Planta 3
28050 Madrid
España / Spain

Skype (Lync): +34 91 312 9084
Mobile: +34 680 947 650
[email-masked]<mailto:[email-masked]>

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Este mensaje y sus adjuntos se dirigen exclusivamente a su destinatario, puede contener información privilegiada o confidencial y es para uso exclusivo de la persona o entidad de destino. Si no es usted. el destinatario indicado, queda notificado de que la lectura, utilización, divulgación y/o copia sin autorización puede estar prohibida en virtud de la legislación vigente. Si ha recibido este mensaje por error, le rogamos que nos lo comunique inmediatamente por esta misma vía y proceda a su destrucción.

The information contained in this transmission is privileged and confidential information intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this transmission in error, do not read it. Please immediately reply to the sender that you have received this communication in error and then delete it.

Esta mensagem e seus anexos se dirigem exclusivamente ao seu destinatário, pode conter informação privilegiada ou confidencial e é para uso exclusivo da pessoa ou entidade de destino. Se não é vossa senhoria o destinatário indicado, fica notificado de que a leitura, utilização, divulgação e/ou cópia sem autorização pode estar proibida em virtude da legislação vigente. Se recebeu esta mensagem por erro, rogamos-lhe que nos o comunique imediatamente por esta mesma via e proceda a sua destruição