Quantum in Too Much Detail
I originally posted this article on the RDO website.
This document describes the architecture that results from a particular OpenStack configuration, specifically:
- Quantum networking using GRE tunnels;
- A dedicated network controller;
- A single instance running on a compute host
Much of the document will be relevant to other configurations, but details will vary based on your choice of layer 2 connectivity, number of running instances, and so forth.
The examples in this document were generated on a system with Quantum
networking but will generally match what you see under Neutron as
well, if you replace
neutron in names. The OVS flow
rules under Neutron are somewhat more complex and I will cover those
in another post.
Moving to GitHub
This blog has been hosted on scriptogram for the past year or so. Unfortunately, while I like the publish-via-Dropbox mechanism, there have been enough problems recently that I've finally switched over to using GitHub Pages for hosting. I've been thinking about doing this for a while, but the things that finally pushed me to make the change were:
- Sync problems that would prevent new posts from appearing (and that at least once caused posts to disappear).
- Lack of any response to bug reports by the site maintainers.
A benefit of the publish-via-Dropbox mechanism is, of course, that I already had all the data and didn't need to go through any sort of export process.read more
A random collection of OpenStack Tools
Why does the Neutron documentation recommend three interfaces?
The documentation for configuring Neutron recommends that a network controller has three physical interfaces:
Before you start, set up a machine to be a dedicated network node. Dedicated network nodes should have the following NICs: the management NIC (called MGMT_INTERFACE), the data NIC (called DATA_INTERFACE), and the external NIC (called EXTERNAL_INTERFACE).
People occasionally ask, "why three interfaces? What if I only have two?", so I wanted to provide an extended answer that might help people understand what the interfaces are for and what trade-offs are involved in using fewer interfaces.read more
Automatic hostname entries for libvirt domains
Have you ever wished that you could use
libvirt domain names as
hostnames? So that you could do something like this:
$ virt-install -n anewhost ... $ ssh clouduser@anewhost
Since this is something that would certainly make my life convenient, I put together a small script called virt-hosts that makes this possible …read more