This is for

• Lakelse Release - Issue #2568 (completed)
• Moselle Release - Pull Request #2676

8. Hybrid Multi-Cloud: Data Centre to Edge

Table of Contents

• 8.1. Introduction
• 8.2. Hybrid Multi-Cloud Architecture
  • 8.2.1. Characteristics of a Federated Cloud
  • 8.2.2. Telco Cloud
  • 8.2.3. Telco Operator Platform Conceptual Architecture
• 8.3. Telco Edge Cloud
  • 8.3.1. Telco Edge Cloud: Deployment Environment Characteristics
  • 8.3.2. Telco Edge Cloud: Infrastructure Characteristics
  • 8.3.3. Telco Edge Cloud: Infrastructure Profiles
  • 8.3.4. Telco Edge Cloud: Platform Services Deployment
  • 8.3.5. Comparison of Deployment Topologies and Edge terms

8.1 Introduction

The Reference Model Chapter 3 focuses on cloud infrastructure abstractions. While these are generic abstractions they and the associated capabilities of the cloud infrastructure are specified for data centres, central office and colocation centres. The environmental conditions, facility and other constraints, and the variability of deployments on the edge are significantly different and, thus, require separate consideration.

It is unrealistic to expect that a private cloud can cost effectively meet the need of all loads, including peak loads and disaster recovery. It is for that reason that enterprises will implement a hybrid cloud. In a hybrid cloud deployment, at least two or more distinct cloud infrastructures are inter-connected together. In a multi-cloud the distinct cloud infrastructures of the hybrid cloud may be implemented using one or more technologies. The hybrid multi-cloud infrastructure has differences requiring different abstractions. These hybrid multi-clouds can be considered to be federated.

In the Reference Model Chapter 3, the cloud infrastructure is defined. The tenants are required to provide certain needed services (such as Load Balancer (LB), messaging). Thus, the VNF/CNFs incorporate different versions of the same services with the resultant issues related to an explosion of services, their integration and management complexities. To mitigate these issues, the Reference Model must specify the common services that every Telco cloud must support and thereby require workload developers to utilise these pre-specified services.

A generic Telco cloud is a hybrid multi-cloud or a Federated cloud that has deployments in large data centres, central offices or colocation facilities, and the edge. This chapter discusses the characteristics of Telco Edge and hybrid multi-cloud.

8.2 Hybrid Multi-Cloud Architecture

The GSMA whitepaper on "Operator Platform Concept Phase 1: Edge Cloud Computing" (January 2020) states, "Given the wide diversity of use cases that the operators will tasked to address, from healthcare to industrial IoT, it seems logical for operators to create a generic platform that can package the existing assets and capabilities (e.g., voice messaging, IP data services, billing, security, identity management, etc. ...) as well as the new ones that 5G makes available (e.g., Edge cloud, network slicing, etc.) in such a way as to create the necessary flexibility required by this new breed of enterprise customers."

Cloud computing has evolved and matured since 2010 when NIST published its definition of cloud computing, with its 5 essential characteristics, 3 service models and 4 deployment models.

The generic model for an enterprise cloud has to be "hybrid" with the special cases of purely private or public clouds as subsets of the generic hybrid cloud deployment model. In a hybrid cloud deployment, at least two or more distinct cloud infrastructures are inter-connected together.

Cloud deployments can be created using a variety of technologies (e.g., OpenStack, Kubernetes) and commercial technologies (e.g., VMware, AWS, Azure, etc.). A multi-cloud deployment can consist of the use of more than one technology.

A generic Telco cloud is a hybrid multi-cloud. A better designation would be a federation of clouds - a federated cloud:

• a collection of cooperating, interoperable autonomous component clouds
• the component clouds perform their local operations (internal requests) while also participating in the federation and responding to other component clouds (external requests)
  • the component clouds are autonomous in terms of, for example, execution autonomy; please note that in a centralised control plane scenario (please see the section "Centralised Control Plane" in the "Edge Computing: Next Steps in Architecture, Design and Testing" whitepaper [26]) the edge clouds do not have total autonomy and are subject to constraints (e.g., workload LCM)
  • execution autonomy is the ability of a component cloud to decide the order in which internal and external requests are performed
• the component clouds are loosely coupled where no changes are required to participate in a federation
  • also, a federation controller does not impose changes to the component cloud except for running some central component(s) of the federated system (for example, a broker agent – executes as a workload)
• the component clouds are likely to differ in, for example, infrastructure resources and their cloud platform software
• workloads may be distributed on single or multiple clouds, where the clouds may be collocated or geographically distributed
• component clouds only surface NBIs (Please note that VMware deployed in a private and a public cloud can be treated as a single cloud instance)

8.2.1 Characteristics of a Federated Cloud

In this section we will further explore the characteristics of the federated cloud architecture, and architecture building blocks that constitute the federated cloud. For example, Figure 8-1 shows a Telco Cloud that consists of 4 sub-clouds: Private on premise, Cloud Vendor provided on premise, Private outsourced (Commercial Cloud Provider such as a Hyperscaler Cloud Provider (HCP), and Public outsourced (see diagram below). Such an implementation of a Telco Cloud allows for mix'n'match of price points, flexibility in market positioning and time to market, capacity with the objective of attaining near "unlimited" capacity, scaling within a sub-cloud or through bursting across sub-clouds, access to "local" capacity near user base, and access to specialised services.

Figure 8-1: Example Hybrid Multi-Cloud Component Cloud

8.2.2 Telco Cloud

The Figure 8-2 presents a visualisation of a Telco operator cloud (or simply, Telco cloud) with clouds and cloud components distributed across Regional Data Centres, Metro locations (such as Central Office or a Colocation site) and at the Edge, that are interconnected using a partial mesh network. Please note that at the Regional centre level the interconnections are likely to be a "fuller" mesh while being a sparser mesh at the Edges.

Figure 8-2: Telco Cloud: Data Centre to Edge

The Telco Operator may own and/or have partnerships and network connections to utilize multiple Clouds for network services, IT workloads, and external subscribers. The types of the component clouds include:

• On Premise Private
  • Open source; Operator or Vendor deployed and managed | OpenStack or Kubernetes based
  • Vendor developed; Operator or Vendor deployed and managed | Examples: Azure on Prem, VMware, Packet, Nokia, Ericsson, etc.
• On Premise Public: Commercial Cloud service hosted at Operator location but for both Operator and Public use | Example: AWS Wavelength
• Outsourced Private: hosting outsourced; hosting can be at a Commercial Cloud Service | Examples: Equinix, AWS, etc.
• (Outsourced) Public: Commercial Cloud Service | Examples: AWS, Azure, VMware, etc.
• Multiple different Clouds can be co-located in the same physical location and may share some of the physical infrastructure (for example, racks)

In general, a Telco Cloud consists of multiple interconnected very large data centres that serve trans-continental areas (Regions). A Telco Cloud Region may connect to multiple regions of another Telco Cloud via large capacity networks. A Telco Cloud also consists of interconnected local/metro sites (multiple possible scenarios). A local site cloud may connect to multiple Regions within that Telco Cloud or another Telco Cloud. A Telco Cloud also consists of a large number of interconnected edge nodes where these edge nodes maybe impermanent. A Telco Cloud's Edge node may connect to multiple local sites within that Telco Cloud or another Telco Cloud; an Edge node may rarely connect to a Telco Cloud Region.

Table 8-1 captures the essential information about the types of deployments, and responsible parties for cloud artefacts.

Table 8-1. Cloud Types and the Parties Responsible for Artefacts

8.2.3 Telco Operator Platform Conceptual Architecture

Figure 8-3 shows a conceptual Telco Operator Platform Architecture. The Cloud Infrastructure Resources Layer exposes virtualised (including containerised) resources on the physical infrastructure resources and also consists of various virtualisation and management software (see details later in this chapter). The Cloud Platform Components Layer makes available both elementary and composite objects for use by application and service developers, and for use by Services during runtime. The Cloud Services Layer exposes the Services and Applications that are available to the Users; some of the Services and Applications may be sourced from or execute on other cloud platforms. Please note that while the architecture is shown as a set of layers, this is not an isolation mechanism and, thus, for example, Users may access the Cloud Infrastructure Resources directly without interacting with a Broker.

Figure 8-3: Conceptual Architecture of a Telco Operator Platform

The Cloud Services and the Cloud Resources Brokers provide value-added services in addition to the fundamental capabilities like service and resource discovery. These Brokers are critical for a multi-cloud environment to function and utilise cloud specific plugins to perform the necessary activities. These Brokers can, for example, provision and manage environments with resources and services for Machine Learning (ML) services, Augmented/Virtual Reality, or specific industries.

8.2.4 Multi-Cloud Interactions Model

8.2.4.1 Introduction

NOTE: Published Lakelse (removed from working materials)

8.2.4.2 Stereo-Typical Scenarios

NOTE: Published Lakelse (removed from working materials)

8.2.4.2 Stereo-Typical Scenarios

NOTE: Published Lakelse (removed from working materials)

8.2.4.3 Requirements, Reference Architecture & Industry Standards Intersect

The Communcations Service Provider (CSP) is both a provider and consumer of Cloud based services. When the CSP is actings as:

• consumer, in which case the typical consideration is total cost of ownership as the consumption is to usually to support internal business operations: BSS/OSS systems;
• provider of cloud services, through operation of their own cloud or reselling of cloud services, in which case the typical consideration is margin (cost to offer services vs income received).

These two stances will drive differing approaches to how a CSP would look to manage how it interacts within a Multi-Cloud environment.

As a consumer of cloud to support internal Business operations and BSS/OSS focus is on meeting the applications needs of organisation which historically came with need to operate support the infrastructure needs of these. This resulted in split of CIO organisation into Delivery and Operations groups. At the same time that CIO application workloads have been moving to SaaS Cloud Providers, CTO Network Systems have been moving from running on dedicated infrastructure to being virtualised and IMS, 3GPP (4G & 5G) functions, IP Routers and Firewalls are being provided as VNFs and CNFs.

As outline in section "8.2.2 Telco Cloud" the result is that the future CSP "network" is a set of distributed NFVi's (Cloud Infrastructure) which will be connected to Cloud Providers and hence the "Hybrid Multi-Cloud" and the need for CSP to be able to support this is both inevitable and essential.

So as a consumer and provider of Cloud Services the CSP will continue to need to build and manage it own Cloud Infrastructure as well as provide network orchestration solution to management interconnectivity across its own and other Cloud Providers. The interactions for this are outlined in the "Multi-Cloud Interactions Model", however to realise this the CSP will need to adopt and sponsor a set of standards that are nessasary to support the interactions.

The follow summary table aims to identify what standards and/or technologies that are seen are applicable.

The criteria for inclusion are

1. Provide capabilities that are necessary to achieve hybrid multi-cloud vision and the multi-cloud interactions
2. Are already mature Open Standards that have either been adopted or nurtured by recognised bodies with the telecommunications industry (e.g. ITU, ETSI, TMForum, GSMA, 3GPP, ISO and national Standards Organiations , (ANSI etc,) NIST)
3. There are reference implementations or an active open source project/s or consortia providing implementations (CNCF. Open Infra)
4. It is possible to source delivery and support services from multiple vendors
5. It is possible for CSP to actively contribute to and request capabilities / coverage of the standard / technology
6. It is not sole proprietary property of a vendor / company
7. Is not focused on "Transactions / Conversations" User / Data Plane standards (typically IETF, IEEE, MEF / Carrier Ethernet etc)

NOTE: Where are the gaps and where is there need to focus and raise priority ?

8.3 Telco Edge Cloud

This section presents the characteristics and capabilities of different Edge cloud deployment locations, infrastructure, footprint, etc. Please note that in the literature many terms are used and, thus, this section includes a table that tries to map these different terms.

8.3.1. Telco Edge Cloud: Deployment Environment Characteristics

Telco Edge Cloud (TEC) deployment locations can be environmentally friendly such as indoors (offices, buildings, etc.) or environmentally challenged such as outdoors (near network radios, curb side, etc.) or environmentally harsh environments (factories, noise, chemical, heat and electromagnetic exposure, etc). Some of the more salient characteristics are captured in Table 8-2.

Table 8-2. TEC Deployment Location Characteristics & Capabilities

8.3.2 Telco Edge Cloud: Infrastructure Characteristics

Commodity hardware is only suited for environmentally friendly environments. Commodity hardware have standardised designs and form factors. Cloud deployments in data centres typically use such commodity hardware with standardised configurations resulting in operational benefits for procurement, installation and ongoing operations.

In addition to the type of infrastructure hosted in data centre clouds, facilities with smaller sized infrastructure deployments, such as central offices or co-location facilities, may also host non-standard hardware designs including specialised components. The introduction of specialised hardware and custom configurations increases the cloud operations and management complexity.

At the edge, the infrastructure may further include ruggedised hardware for harsh environments and hardware with different form factors.

8.3.3 Telco Edge Cloud: Infrastructure Profiles

The Cloud Infrastructure Profiles section specifies two infrastructure profiles:

The Basic cloud infrastructure profile is intended for use by both IT and Network Function workloads that have low to medium network throughput requirements.

The High Performance cloud infrastructure profile is intended for use by applications that have high network throughput requirements (up to 50Gbps).

The High Performance profile can specify extensions for hardware offloading; please see Hardware Acceleration Abstraction. The Reference Model High Performance profile includes an initial set of High Performance profile extensions.

Based on the infrastructure deployed at the edge, Table 8-3 specifies the Infrastructure Profile features and requirements that would need to be relaxed.

Table 8-3. TEC Exceptions to Infrastructure Profile features and requirements

^* immaterial if the number of CPU sockets (infra.hw.cpu.cfg.001) is 1

Please note that none of the listed parameters form part of a typical OpenStack flavour except that the vCPU and memory requirements of a flavour cannot exceed the available hardware capacity.

8.3.4 Telco Edge Cloud: Platform Services Deployment

This section characterises the hardware capabilities for different edge deployments and the Platform services that run on the infrastructure. Please note, that the Platform services are containerised to save resources, and benefit from intrinsic availability and auto-scaling capabilities.

Table 8-4. Characteristics of Infrastructure nodes

Depending on the facility capabilities, deployments at the edge may be similar to one of the following:

• Small footprint edge device
• Single server: deploy multiple (one or more) workloads
• Single server: single Controller and multiple (one or more) workloads
• HA at edge (at least 2 edge servers): Multiple Controller and multiple workloads

8.3.5 Comparison of Deployment Topologies and Edge terms

Table 8-5. Comparison of Deployment Topologies