[Teas] ACTN and Network Slicing in draft-ietf-teas-ietf-network-slice-framework

Adrian Farrel <adrian@olddog.co.uk> Tue, 30 March 2021 08:31 UTC

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From: "Adrian Farrel" <adrian@olddog.co.uk>
To: "'TEAS WG'" <teas@ietf.org>
Cc: <draft-ietf-teas-ietf-network-slice-framework@ietf.org>
Date: Tue, 30 Mar 2021 09:31:38 +0100
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Subject: [Teas] ACTN and Network Slicing in draft-ietf-teas-ietf-network-slice-framework
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Hi authors of draft-ietf-teas-ietf-network-slice-framework and TEAS WG,

I've been looking at the ACTN section in this draft. I think it is good
that this draft makes it clear that ACTN is an applicable technology
for creating and managing network slices: ACTN is core TEAS mechanism
and we should make it available for re-use where possible.

However, I think that applying ACTN to network slicing needs more text
than it is appropriate to place in this document. You currently have 2
pages out of about 11 pages of text. While I expect the total will grow
as more material is added across the document, I also think that adding
more substance to the ACTN section would put it completely out of
balance.

My suggestion is that we:
- revise down the ACTN text in this document
- make a reference to a separate document to describe the applicability
  of ACTN
I would (obviously?) suggest draft-king-teas-applicability-actn-slicing
as the document to be referenced although it will need some work to
bring it into line with the terminology work that has been done in TEAS.

My suggested edits to this document are:


3.2
OLD
   Layered virtual connections are comprehensively discussed in IETF
   documents and are widely supported.  See, for instance, GMPLS-based
   networks ([RFC5212] and [RFC4397]), or ACTN ([RFC8453] and
   [RFC8454]).  The principles and mechanisms associated with layered
   networking are applicable to IETF network slices.
NEW
   Layered virtual connections are comprehensively discussed in IETF
   documents and are widely supported.  See, for instance, GMPLS-based
   networks [RFC5212] and [RFC4397], or Abstraction and Control of TE
   Networks (ACTN) [RFC8453] and [RFC8454].  The principles and
   mechanisms associated with layered networking are applicable to IETF
   network slices.
END

---

3.5

OLD
   Also, as outlined in "applicability of ACTN to IETF Network Slices"
   below, ACTN ([RFC8453]) offers a framework that is used elsewhere in
   IETF specifications to create virtual network (VN) services similar
   to IETF network slices.
NEW
   Also, as described in Section 4, below, ACTN offers a framework that
   is used elsewhere in IETF specifications to create virtual network
   (VN) services similar to IETF network slices.
END

---

4. COMPLETE REPLACEMENT

4.  Applicability of ACTN to IETF Network Slices

   Abstraction and Control of TE Networks (ACTN - [RFC8453]) is a
   management architecture and toolkit used to create virtual networks
   (VNs) on top of a traffic engineering (TE) underlay network.  The VNs
   can be presented to customers for them to operate as private 
   networks.

   In many ways, the function of ACTN is similar to IETF network
   slicing.  Customer requests for connectivity-based overlay services
   are mapped to dedicated or shared resources in the underlay network 
   in a way that meets customer guarantees for service level objectives
   and for separation from other customers' traffic.  [RFC8453] the
   function of ACTN as collecting resources to establish a logically
   dedicated virtual network over one or more TE networks.  Thus, in the
   case of a TE-enabled underlying network, the ACTN VN can be used as a
   basis to realize an IETF network slicing.

   While the ACTN framework is a generic VN framework that can be used
   for VN services beyond the IETF network slice, it also a suitable
   basis for delivering and realizing IETF network slices.

   Figure 1 illustrates the mapping between IETF network slice 
   management and interfaces, and the ACTN management components and 
   interfaces.  For reference, the ACTN abbreviations are as follows:
     CNC  : Customer Network Controller
     MDSC : Multi-Domain Service Coordinator
     PNC  : Provisioning Network Controller
     CMI  : CNC-MDSC Interface
     MPI  : MDSC-PNC Interface


                IETF Network Slice                |   ACTN analogous
              Terminology / Concepts                  Terminology
                                                  |    and Concepts
       +--------------------------------------+
       |Consumer higher level operation system|   |    +-----+
       | (e.g E2E network slice orchestrator) | =====> | CNC |
       +--------------------------------------+   |    +-----+
                         ^                                ^
                         | NSC NBI                |       | CMI
                         v                                v
       +-------------------------------------+    |    +------+
       | IETF Network Slice Controller (NSC) |  =====> | MDSC |
       +-------------------------------------+    |    +------+
                         ^                                ^
                         | NSC SBI                |       | MPI
                         v                                v
       +-------------------------------------+    |    +-----+
       |        Network Controller(s)        |  =====> | PNC |
       +-------------------------------------+    |    +-----+

   Figure 1 : Mapping Between IETF Network Slice and ACTN Components


   Note that the details of all function below the NSC SBI are out of
   scope of this document.

   Further discussion of the applicability of ACTN to IETF network
   slices including a discussion of the relevant YANG models can be 
   found in [I-D.king-teas-applicability-actn-slicing].

---

Hope this helps.

Best,
Adrian