Information technology (IT) applications are rapidly moving from dedicated infrastructure to a dynamic cloud-based infrastructure. This move to cloud started with server virtualization, where a hardware server ran as a virtual machine on a hypervisor. The adoption of cloud-based applications has accelerated due to factors such as globalization and outsourcing, where diverse teams need to collaborate in real time.
Server hardware connects to network switches using Ethernet and IP to establish network connectivity. However, as servers move from physical to virtual, the network boundary also moves from the physical network to the virtual network. Traditionally, applications, servers, and networking were tightly integrated. But modern enterprises and IT infrastructure demand flexibility in order to support complex applications.
The flexibility of cloud infrastructure requires networking to be dynamic and scalable. Software-Defined Networking (SDN) and Network Function Virtualization (NFV) play a critical role in data centers in order to deliver the flexibility and agility demanded by cloud-based applications. By providing practical management tools and abstractions that hide the underlying physical network's complexity, SDN allows operators to build complex networking capabilities on demand.
OpenStack is an open source cloud platform that helps build public and private cloud at scale. Within OpenStack, the name for the OpenStack Networking project is Neutron. The functionality of Neutron can be classified as core and service.
This chapter aims to provide a short introduction to OpenStack Networking. We will cover the following topics in this chapter:
Understanding traffic flows between virtual and physical networks
Neutron entities that support Layer 2 (L2) networking
Layer 3 (L3) or routing between OpenStack networks
Securing OpenStack network traffic
Advanced networking services in OpenStack
OpenStack and SDN
The terms Neutron and OpenStack Networking are used interchangeably throughout this book.