Re: [Teas] Two more examples for draft-ietf-teas-ietf-network-slices

["Dongjie (Jimmy)" <[e-mail]>]

Hi Adrian,

Thanks for proposing text for the hierarchical and multi-domain E2E network slice cases. They look good to me in general, and I agree with adding them as examples to the slice framework draft. 

Here are a few clarification comments: 

1. The example in figure 10 talks about "bridging connectivity", which is a little confusing to me. My reading is that figure gives an example of using hierarchical network slices to provide the connectivity with required SLA/SLO to an upper layer network slice, then I'm not sure whether it needs to be called something special as "Bridge Connectivity". Or maybe I misunderstood something about this case?

2. In the description about the coordination of multiple intra-domain network slices, it is suggested to make some change to the following sentence to align with the network slice definition:

  Old: The coordination activity involves binding the SDPs, and hence the connectivity constructs, to achieve end-to-end connectivity.

  Proposed: The coordination activity involves binding the SDPs, and hence the connectivity constructs, to achieve end-to-end connectivity with the required SLA and SLO.

Best regards,
Jie

> -----Original Message-----
> From: Teas [mailto:[e-mail]] On Behalf Of Adrian Farrel
> Sent: Sunday, July 31, 2022 4:10 PM
> To: [e-mail]
> Subject: [Teas] Two more examples for draft-ietf-teas-ietf-network-slices
> 
> Hi,
> 
> During the meeting at IETF-114, Lou suggested that we might make some
> efforts to include a discussion of hierarchical and concatenated IETF Network
> Slices within the framework draft.
> 
> We already have some text that notes that these approaches fall within the
> architecture, so probably nothing new needed there. But the Appendix
> provides a place to give simple examples of various deployment options
> (without getting into the details of realisation).
> 
> So, here is some proposed text.
> 
> Let me know if it causes any of you a problem.
> 
> Cheers,
> Adrian
> 
> ====
> 
> A.5.  Hierarchical Composition of Network Slices
> 
>    As mentioned in Section 4.3, IETF Network Slices may be arranged
>    hierarchically.  There is nothing special of novel about such an
>    arrangement, and it models the hierarchical arrangement of services
>    of virtual networks in many other environments.
> 
>    As shown in Figure 9, an Operator's Controller (NSC) that is
>    requested to provide an IETF Network Slice for a customer may, in
>    turn, request an IETF Network Slice from another carrier.  The
>    Operator's NSC may manage and control the underlay IETF Network Slice
>    by modifying the requested connectivity constructs and changing the
>    SLAs.  The customer is entirely unaware of the hierarchy of slices,
>    and the underlay carrier is entirely unaware of how its slice is
>    being used.
> 
>    This "stacking" of IETF Network Slice constructs is no different to
>    the way virtual networks may be arranged.
> 
>                --------------
>               | Network      |
>               | Slice        |
>               | Orchestrator |
>                --------------
>                 | IETF Network Slice
>                 | Service Request
>                 |                    Customer view
>             ....|................................
>                -v----------------    Operator view
>               |Controller        |
>               |  ------------    |
>               | | IETF       |   |
>               | | Network    |---|---
>               | | Slice      |   |   |
>               | | Controller |   |   |
>               | | (NSC)      |   |   |
>               |  ------------    |   |
>                ------------------    |
>                                      | IETF Network Slice
>                                      | Service Request
>                                      |
>             .........................|.....................
>                            ----------v-------    Carrier view
>                           |Controller        |
>                           |  ------------    |
>                           | | IETF       |   |
>                           | | Network    |   |--> Virtual Network
>                           | | Slice      |   |
>                           | | Controller |   |
>                           | | (NSC)      |   |
>                           |  ------------    |
>                       ....|  | Network       |............
>                           |  | Configuration |   Underlay Network
>                           |  v               |
>                           |  ------------    |
>                           | | Network    |   |
>                           | | Controller |   |
>                           | | (NC)       |   |
>                           |  ------------    |
>                            ------------------
>                             | Device Configuration
>                             v
> 
>      Figure 9: Example Hierarchical Arrangement of IETF Network Slices
> 
>    In this case, the network hierarchy may also be provided to bridge
>    connectivity between networks as shown in Figure 10.  Here, the an
>    IETF Network Slice may be requested of the lower layer network to
>    provide the desired connectivity constructs to supplement the
>    connectivity in the higher layer network where this connectivity may
>    be presented as a virtual link.
> 
>                   CE1                                       CE2
>                    |                                         |
>                    |                                         |
> 
> _|_________________________________________|_
>                  ( :                                         : )
>                 (  :..............             ..............:  )
> 
> (_______________:_____________:_______________)
>                                __|_____________|__
>                               (  :             :  )
>                              (   :.............:   )
>                               (___________________)
> 
>         Figure 10: Example Hierarchical Arrangement of IETF Network
>                        Slices to Bridge Connectivity
> 
> A.6.  Horizontal Composition of Network Slices
> 
>    It may be that end-to-end connectivity is achieved using a set of
>    cooperating networks as described in Section 4.3.  For example, there
>    may be multiple inter-connected networks that provide the required
>    connectivity as shown in Figure 11.  The networks may utilize
>    different technologies and may be under separate administrative
>    control.
> 
>                   CE1                                       CE2
>                    |                                         |
>                   SDP1                                      SDP2
>                    |                                         |
>                   _|____       ______       ______       ____|_
>                  (      )     (      )     (      )     (      )
>                 (        )---(        )---(        )---(        )
>                  (______)     (______)     (______)     (______)
> 
>         Figure 11: Example Customer View of Inter-connected Networks
>                       Provide End-to-End Connectivity
> 
>    In this scenario, the customer (represented by CE1 and CE2) may
>    request an IETF Network Slice service connecting the CEs.  The
>    customer considers the SDPs at the edge (shown as SDP1 and SDP2 in
>    Figure 11) and might not be aware of how the end-to-end connectivity
>    is composed.
> 
>    However, because the various networks may be of different
>    technologies and under separate administrative control, the networks
>    are sliced individually and coordination is necessary to deliver the
>    desired connectivity.  The network to network interfaces (NNIs) are
>    present as SDPs for the IETF Network Slices in each network so that
>    each network is individually sliced.  In the example in Figure 11,
>    this is illustrated as network 1 (N/w1) being sliced between SDP1 and
>    SDPX, N/w2 being sliced between SDPY and SDPU, etc.  The coordination
>    activity involves binding the SDPs, and hence the connectivity
>    constructs, to achieve end-to-end connectivity.  In this way, simple
>    and complex end-to-end connectivity can be achieved with a variety of
>    connectivity constructs in the IETF Network Slices of different
>    networks "stitched" together.
> 
>               CE1
> CE2
>                |                                                  |
>               SDP1
> SDP2
>                |                                                  |
>               _|____          ______          ______
> ____|_
>              (      ) SDPX   (      ) SDPU   (      ) SDPS   (      )
>             (  N/w1  )------(  N/w2  )------(  N/w3  )------(  N/w4  )
>              (______)   SDPY (______)   SDPV (______)   SDPT
> (______)
> 
> 
>       Figure 12: Example Delivery of An End-to-End IETF Network Slice
>                        with Inter- connected Networks
> 
>    The controller/coordinator relationship is shown in Figure 13.
> 
>           --------------
>          | Network      |
>          | Slice        |
>          | Orchestrator |
>           --------------
>            | IETF Network Slice
>            | Service Request
>            |                    Customer view
>        ....|................................
>           -v----------------    Coordinator view
>          |Coordinator       |
>          |                  |
>           ------------------
>            |             |_________________
>            |                               |
>            |                               |
>        ....|.......................    ....|.....................
>           -v--------------                -v--------------
>          |Controller1     | Operator1    |Controller2     | Operator2
>          |  ------------  |              |  ------------  |
>          | | IETF       | |              | | IETF       | |
>          | | Network    | |              | | Network    | |
>          | | Slice      | |              | | Slice      | |
>          | | Controller | |              | | Controller | |
>          | | (NSC)      | |              | | (NSC)      | |
>          |  ------------  |              |  ------------  |
>      ....|  | Network     |............  |  | Network     |............
>          |  | Config      | Underlay1    |  | Config      | Underlay2
>          |  v             |              |  v             |
>          |  ------------  |              |  ------------  |
>          | | Network    | |              | | Network    | |
>          | | Controller | |              | | Controller | |
>          | | (NC)       | |              | | (NC)       | |
>          |  ------------  |              |  ------------  |
>           ----------------                ----------------
>            | Device Configuration
>            v
> 
>      Figure 13: Example Relationship of IETF Network Slice Coordination
> 
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