Book Image

OpenStack Cloud Security

By : Fabio Alessandro Locati
Book Image

OpenStack Cloud Security

By: Fabio Alessandro Locati

Overview of this book

Table of Contents (14 chapters)
OpenStack Cloud Security
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

The Open Systems Interconnection model


In 1984, ISO/IEC 7498-1 was published, which defines the Open Systems Interconnection (OSI) model. The OSI model is a theoretical model to divide a communication between two machines in abstraction layers.

Note

Even if the OSI model is not used in the real world, it is critical, because it helps you to understand the networking communications and their implications clearly. Also, very often, those layers are referred to in networking, in phrases such as "we got a problem on layer 3".

The OSI model consists of the following seven layers:

  1. Physical

  2. Data link

  3. Network

  4. Transport

  5. Session

  6. Presentation

  7. Application

Layer 1 – the Physical layer

This is the lowest layer and it relates the physical part, as the name suggests. This layer cares about bit stream, so it will be electrical, light, or radio impulses.

The following are the standards that fall in this layer:

  • IEEE 802.11a/b/g/n/ac (WiFi)10BASE-T

  • 100BASE-TX

  • 1000BASE T

  • 10GBASE T

  • 40GBASE-T (Ethernet standards over RJ-45 twisted...