Re: [Teas] network Slice Endpoint in draft-ietf-teas-ietf-network-slice-definition-00

[Kiran Makhijani <[e-mail]>]

Reza, and all,
Agreed, architecturally, network slice is a type of network, based on the discussion, maybe NSEs can be called NS-AP (access points) and their realizations remain unchanged – NSREs?
Looking forward to the updated figure.
Cheers,
Kiran

From: Teas <[e-mail]> on behalf of Rokui, Reza (Nokia - CA/Ottawa) <[e-mail]>
Date: Wednesday, February 10, 2021 at 10:10
To: [e-mail] <[e-mail]>, 'John E Drake' <jdrake=[e-mail]>, 'Joel M. Halpern' <[e-mail]>, [e-mail] <[e-mail]>
Cc: Rokui, Reza (Nokia - CA/Ottawa) <[e-mail]>
Subject: Re: [Teas] network Slice Endpoint in draft-ietf-teas-ietf-network-slice-definition-00
Hi Adrian,

My comment is inlined.

Reza



From: Adrian Farrel <[e-mail]>
Organization: Old Dog Consulting
Reply-To: "[e-mail]" <[e-mail]>
Date: Wednesday, February 10, 2021 at 12:29 PM
To: 'John E Drake' <jdrake=[e-mail]>, Reza Rokui <[e-mail]>, "'Joel M. Halpern'" <[e-mail]>
Cc: "[e-mail]" <[e-mail]>
Subject: RE: [Teas] network Slice Endpoint in draft-ietf-teas-ietf-network-slice-definition-00

Hi all,

In case this discussion is getting heated, can I observe that I find Figure 2 of RFC 3985 hugely useful in this context. Yes, it is only referring to a P2P service and not an MP2MP service, but the same concepts apply and it is likely that all our figures will only show P2P anyway.

You might note that that figure does not use the term “end point” and does this without any loss of meaning. However, whether the terms CE and PE will be applicable for us (probably they are) is up for debate.
[Reza] this picture might be useful but without referring to PE and CE. IMO it is not applicable to our discussion since IETF network slice is technology-agnostic.

You might also note that the rest of 3985 *does* use the term “endpoint” but it does so only to refer to “tunnel endpoints”.

Let’s step even further back from this.
Is a network slice “connectivity” or does is it a network service?
[Reza] In Definition draft the co-authors intentionally did not use term “Service” since this term is overloaded and anybody can have his own interpretation.
So, IETF network slice is a group of connections between multiple endpoints which are realized in the operator’s transport network using any L0/L1/L2/L3 services/tunnels.
Note that the transport network might either be IP/MPLS or other technologies (e.g. PON)


Connections, tunnels, links all have end points.
Services have “service delivery points” and “access points”.
Or is a slice a type of network (virtual or logical or sliced)?
Networks have “edges” and “access points”.
[Reza] Good point Adrian. All these are related to “IETF Network Slice REALIZATION”. So any L0/L1/L2/L3 services/tunnels used to realize the IETF network slice will have its own access point, endpoints etc.
These are different from “IETF Network Slice Endpoints” but obviously there will be a relationship between them.


Adrian

From: Teas <[e-mail]> On Behalf Of John E Drake
Sent: 10 February 2021 16:21
To: Rokui, Reza (Nokia - CA/Ottawa) <[e-mail]>; [e-mail]; 'Joel M. Halpern' <[e-mail]>; [e-mail]
Subject: Re: [Teas] network Slice Endpoint in draft-ietf-teas-ietf-network-slice-definition-00

Hi,

Comment inline

Yours Irrespectively,

John



Juniper Business Use Only
From: Teas <[e-mail]<mailto:[e-mail]>> On Behalf Of Rokui, Reza (Nokia - CA/Ottawa)
Sent: Wednesday, February 10, 2021 7:39 AM
To: [e-mail]<mailto:[e-mail]>; 'Joel M. Halpern' <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>
Cc: Rokui, Reza (Nokia - CA/Ottawa) <[e-mail]<mailto:[e-mail]>>
Subject: Re: [Teas] network Slice Endpoint in draft-ietf-teas-ietf-network-slice-definition-00

[External Email. Be cautious of content]


Joel and Adrian,



Agreed that there shall be clarity about the endpoints.



                >>>>>> There are traffic endpoints (the sender and receiver of packets), and there are endpoints of the service (the ingress and egress to the slice).

This is correct Adrian.



An “IETF network slice” is between two or more endpoints as outlined in the draft.

In summary, the  IETF network slice is defined  between various device/applications/network functions on multiple “IETF network slice endpoints”.  These are traffic endpoints of the IETF network slice. We refer to them in the draft as “NSE” (IETF Network Slice Endpoints).

In addition , as Adrian mentioned there are endpoints to the realization of the transport slice (i.e. various services/tunnels/paths). I am suggesting to use term “NSI” (IETF Network Slice Ingress).  Please provide your suggestions for NSI if you have any other suggestions.



                >>>> For example, if the service is being

    delivered with MPLS, the Network Slice Endpoint likely cannot put the

    labels on the packet for the MPLS, as it is outside of the IETF network

    Slice.  So we will need yet another layer of classification, and yet

    more interworking.



This is not correct.  Whatever technology is used to realize the IETF network slice must be supported by endpoints. If MPLS is technology of choice, the endpoint must support it in its data-path (and might also support it in its control-plane).



[JD]  This is incorrect.   E.g., in IETF VPNs, the traffic from the CE to the PE is *not* MPLS encapsulated.  It is the PE that does the encapsulation.



Cheers,



Reza



    ------------------Original Message-----------------------



On 2021-02-05, 5:29 PM, "Teas on behalf of Adrian Farrel" <[e-mail] on behalf of [e-mail]<mailto:[e-mail][e-mail]>> wrote:



    Ah, the old "endpoint" discussion.



    Yes, Joel is right, we need to disambiguate endpoints from endpoints.

    There are traffic endpoints (the sender and receiver of packets), and there

    are endpoints of the service (the ingress and egress to the slice).



    There is probably a risk that we get sucked in to the wider 5G picture, but

    we need to focus (as Joel says) on the IETF network slice.



    I suggest "source/destination" and "IETF network slice ingress/egress".



    And we can avoid discussion of the wider 5G context, as noted elsewhere in

    the draft, by diverting that material into a dedicated document.



    Cheers,

    Adrian



    -----Original Message-----

    From: Teas <[e-mail]<mailto:[e-mail]>> On Behalf Of Joel M. Halpern

    Sent: 05 February 2021 17:04

    To: [e-mail]<mailto:[e-mail]>

    Subject: [Teas] network Slice Endpoint in

    draft-ietf-teas-ietf-network-slice-definition-00



    Rereading this draft, I realized that I am either confused by or

    disagree with the description of the "Network Slice Endpoint" contianed

    there.





    The endpoint that I think matters is the place where the IETF Network

    Slice Controller starts controlling the QoS and traffic delivery.  The

    Controller doesn't care about the identity of the device outside of that.



    Figure 1 in section 4.2 seems to define that endpoint as the network

    slice realiation endpoint, and describes the network slice endpoint as

    the thing outside the IetF network slice.  This seems counter-productive

    to me.  It complicates teh relationship between the endpoitn and the

    service being abstracted.  For example, if the service is beign

    delivered with MPLS, the Network Slice Endpoint likely can not put the

    labels on the packet for the MPLS, as it is outside of the IETF network

    Slice.  So we will need yet another layer of classification, and yet

    more interworking.

    Further, someone has to get the queueing right for traffic coming out of

    the Network Slice Endpoint.  But it is not part of the IETF Network

    Slice, so we don't have any way to get it right.



    If we define the edge of the space we care about co-incident with the

    edge of the space we influence, things get a lot cleaner.



    Yours,

    Joel



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