Review/Perspective: Cloud Deployment Models

7.1.a Compare and contrast Cloud deployment models

  • 7.1.a [i] Infrastructure, platform, and software services [XaaS]
  • 7.1.a [ii] Performance and reliability
  • 7.1.a [iii] Security and privacy
  • 7.1.a [iv] Scalability and interoperability


XaaS consists of the following:

Software as a service (SaaS) – application services are delivered over a network on a subscription and on-demand basis.

Platform as a Service (PaaS) – run-time environments and software dev frameworks delivered over the network on a pay as you go basis.  Typically presented as APIs to customers.

Infrastructure as a Service (IaaS) – compute, network, and storage are delivered over the network on a pay as you go basis.

Performance and reliability:

Cloud deployments require high availability to maintain network services to customers. This requires careful consideration of Fault tolerance, in that network design engineers have to account for this when coming up with redundancy plans for datacenter environments.

Automation reduces TCO and makes it easier for engineers to do things, such as creating VLANs, testing MPLS traffic engineering, or creating backups.  The tradeoff involves maintenance of the software in the form of in house development of the automation services that are running.  This benefit of automation becomes more prevalent in larger network deployments as the costs of maintaining the automation are typically less than the cost of a large IT staff.

Automation should be deployed where it makes sence, and where it can be maintained with a reasonable amount of effort. This is how performance and reliability are maximized.  Accessibility also needs to be considered to ensure sufficient bandwidth is available to reach the cloud environment.

Security and Privacy

Security related to cloud deployments many consider public cloud security to be more secure than private cloud security where digital security is strong and all communications are secured over the public internet, the counter argument to this is that physical security can be questionable.  Geographic diversity in the event of natural disasters is something to consider in addition to the specific region where cloud data is actually stored.  Some regions of the world known to have unfriendly relations towards the home country is something to think about.  These uncertainties can be accounted for by using availability zones, where cloud providers will ensure data is confined within a specific geographic region.

Scalability and Interoperability

Achieving cloud scalability relies on a few components supporting cloud architecture such as network fabric, application design, and virtualization/segmentation design.

  • Public cloud
    • Scalability – Appears to be infinite which allows customers to provision new services fast
    • Interoperability – developers choose which cloud provider APIs to use, these are typically offered as part of the cloud offering.
  • Private Cloud
    • Scalability – High capital and operating expenses to expand which limits scale
    • Interoperability – Works with underlying platform (ie openstack application should be deployable to another openstack instance.)
  • Virtual Private Cloud
    • Scalability – Scales well with public cloud resources
    • Interoperability – Combination of public/private depending on where resources are located.  Migration between the two could limit interoperability depending on where APIs are located
  • Inter-Cloud
    • Scalability – Highest scalability massively distributed architecture
    • Interoperability – up to dev to use cloud provider apis, assumes consistent api presentation between different cloud AS’s

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