Book Image

Learning OpenStack Networking - Third Edition

By : James Denton
Book Image

Learning OpenStack Networking - Third Edition

By: James Denton

Overview of this book

OpenStack Networking is a pluggable, scalable, and API-driven system to manage physical and virtual networking resources in an OpenStack-based cloud. Like other core OpenStack components, OpenStack Networking can be used by administrators and users to increase the value and maximize the use of existing datacenter resources. This third edition of Learning OpenStack Networking walks you through the installation of OpenStack and provides you with a foundation that can be used to build a scalable and production-ready OpenStack cloud. In the initial chapters, you will review the physical network requirements and architectures necessary for an OpenStack environment that provide core cloud functionality. Then, you’ll move through the installation of the new release of OpenStack using packages from the Ubuntu repository. An overview of Neutron networking foundational concepts, including networks, subnets, and ports will segue into advanced topics such as security groups, distributed virtual routers, virtual load balancers, and VLAN tagging within instances. By the end of this book, you will have built a network infrastructure for your cloud using OpenStack Neutron.
Table of Contents (16 chapters)

Exploring how instances retrieve their metadata

In Chapter 3, Installing Neutron, we briefly covered the process of instances accessing metadata over the network: either through a proxy in the router namespace or the DHCP namespace. The latter is described in the following section.

The DHCP namespace

Instances access metadata at http://169.254.169.254, followed by a URI that corresponds to the version of metadata, which is usually /latest. When an instance is connected to a network that does not utilize a Neutron router as the gateway, the instance must learn how to reach the metadata service. This can be accomplished in a few different ways, including the following:

  • Setting a route manually on the instance
  • Allowing DHCP...