[Netslices] Preliminary charter text for discussion

[Xavier de Foy <[e-mail]>]

Hi all, a group of COMS proponents prepared a preliminary charter text,
taking into account recommendations collected when discussing the BoF
request for IETF 100
<https://trac.tools.ietf.org/bof/trac/wiki/BofIETF100#OperationsandManagement>
.

The recommendations were for:
1. better account of the 4 key elements used in COMS: connectivity,
compute, storage resources + network & service functions;
2. better description of the functional blocks and their positions in COMS;
3. better FCAPS coverage;
4. better coverage of the management of the data plane.

Please share your comments on this list by Feb 1st. Other COMS proponents
are also invited to provide additional information to help with the
discussion.

Best Regards,
Xavier, on behalf of COMS proponents.


I. Context

The Common Operations and Management on Network Slices (COMS) WG
standardizes slice-level operations and management of the resources
associated with a network slice. These resources include both network
infrastructures and service functions. More specifically, network
infrastructures are normally comprised of physical/logical connections in
access, aggregation and backbone networks as well as computing and storage
elements. Meantime, service functions include network functions and network
function chains which are pre-defined using corresponding network
infrastructure elements. Such resources may be parts of different domains
enabled by different technologies.

A "Network Slice" is realized using a collection of technologies spanning
across data, control and management planes. Many of them rely on existing
IETF technologies including both concluded and in-progress works such as:
- Data plane: DetNet, TE-Tunnels, MPLS, Segment Routing VPNs, NVO3 etc.
- Controller and/or control plane: ACTN, PCE and RSVP-TE (requiring LDP,
BGP, OSPF awareness at level below) etc.
- Management plane: YANG, OAM etc.

The foundation of COMS is a technology-independent and resource-centric
management plane. In reality, the network slice provider may have diverse
technology choices in different domains due to geographical and commercial
reasons. Therefore, COMS makes no assumption on which technology is used
for specific domains. The goal of COMS is to define a common and
inter-operative management mechanism, which is essential for the concept of
network slicing being adopted in a system with heterogeneous network
infrastructures and services functions. Major characteristics include:
- Enabling composition of slices within a single or over multiple domains.
- Allowing the operation and management of a network slice in a uniform
manner, even when this network slice span multiple technology and/or
administrative domains.
- Enabling deployment of services over individual slices.

II. Scope

The WG will describe an overall architecture for network slicing. To manage
network slices in a technology-independent manner, the network slice
provider (NSP) will need to communicate with a network slice orchestrator
(NSO) over a COMS Service Delivery Interface (SDI). The COMS SDI can also
be used between network slice orchestrators, enabling hierarchical
management through the notion of network slice subnets. Network slices will
be leased to tenants, which will be able to use Customer Service Interface
(CSI) exposed by the NS provider to run management tasks (e.g., on-demand
measurement) within their slice instance under certain policies.

The WG will describe an information model representing a network slice,
accounting for the key elements used in network slices: connectivity,
compute, storage resources, network and service functions — this
information model includes the representation of managed objects and
corresponding management and operations, will guide the design of data
models on SDI and CSI and also will enable orchestrators interworking.

The WG will specify requirements, operations and management functionalities
on network slicing interfaces SDI and/or CSI including:
1 Network slice service profile, e.g. set by NSP over SDI, including
high-level parameters for network infrastructures and service functions,
together with their corresponding performance requirements.
2 Lifecycle management of network slice.
3 Other FCAPS functions. An important task of NSP is to aggregate faults,
performance, status information and performance guarantees for certain
services.
4 Slice composition or stitching in multi-domain environment.
5 Slice management by the tenant under the control of NSP, including
deploying network services over a slice.

The WG will specify requirements and functionalities of data plane entities
as needed to enable the management of network slices. For example, this may
include abstractions of policy control and enforcement, or gateway
functionalities. The WG will also study the mapping between the abstract
information model and managed entities, and will liaise with other IETF WGs
as needed. However, the WG will not attempt to replicate data plane
technologies including DetNet, TE-Tunnels, MPLS, Segment Routing VPNs, NVO3
etc.

III. Deliverables

WG deliverables are listed below and may be split in any number of
documents as determined by the WG:
- Problem statement and use cases for management of network slices.
- Architecture of network slices.
- Information model(s) and operations for network slices on topics
described above in the scope section.
- SDI and CSI interface specifications and relevant YANG models.
- Study the mappings of technology independent network equipment
configurations derived from the information model towards specific
technologies and coordination with relevant WGs as needed.

IV. Milestones

Dec 2018     Problem Statement, use cases and architecture
Dec 2018     Common information model and related YANG model
June 2019    Network slices composition and interworking
October 2019 FCAPS management functions and operations on network
             slices including abstractions of policy control and
             enforcement, or gateway functionalities.
March 2020   SDI and CSI interface specifications and relevant YANG models