The Cisco GCI uses the NIST definition of cloud
computing in defining cloud data centers and defines
five essential characteristics of a cloud data center:
• On-demand self-service
• Broad network access
• Resource pooling
• Rapid elasticity
• Measured service
Broadly speaking, cloud data centers support three
service models: software as a service (SaaS), platform
as a service (PaaS), and infrastructure as a service (IaaS).
Cloud data centers also support four deployment models:
private cloud, community cloud, public cloud and hybrid
cloud. Figure 6 provides a graphical depiction of a hybrid
cloud model, which is increasingly relevant for the
enterprise market.8
60%
50%
40%
30%
20%
10%
October/November/December 2020 I 51
• Worldwide cloud traffic will more than triple.
• Hyperscale data centers will represent 53
percent of all installed data center servers
(Figure 5) and will grow in number to 628,
up from 338 at the end of 2016.
Networking in the Cloud
The term “cloud” can cover many definitions and
meanings. The National Institute of Standards and
Technology (NIST) developed “The NIST Definition
of Cloud Computing,”7 in 2011, explaining that “cloud
computing is a model for enabling ubiquitous, convenient,
on-demand network access to a shared pool
of configurable computing resources (e.g., networks,
servers, storage, applications, and services) that can
be rapidly provisioned and released with minimal
management effort or service provider interaction.”
Hyperscale Data Centers
13% CGAR 2016-2021
700
600
500
400
300
200
100
0
0%
% Share
of Data
Center
Servers
(Installed
Base)
27%
338
2016
32%
386
2017
38%
448
2018
44%
509
2019
48%
570
2020
53%
628
2021
FIGURE 5: Global hyperscale data center growth. Source: Cisco Global Cloud Index, 2016-2021.
Private
Cloud
Google
Azure
AWS
Hybrid Cloud
Enterprise Data Center Public Clouds
Multi Cloud
FIGURE 6: Model of a hybrid cloud.