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Networking fundamentals

asked 2017-05-03 23:04:40 -0500

sanjana gravatar image

updated 2017-05-04 22:43:48 -0500

Basically there are 3 types of network managers in OpenStack, 1. Flat 2. Flat DHCP 3. VLAN

Where does VxLan and GRE come into picture in case of networking openstack.

In my setup, i have installed openstack on 2 nodes running ubuntu 16.04. I have used linux bridge for the installation. While setting up the external network in Horizon i have selected provider network type flat. During the install i followed steps for self service network. So i assumed i should be able to create external network in horizon using vxlan. BUt VMs had access issue. The output of external network :image description

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answered 2017-05-03 23:49:01 -0500

dbaxps gravatar image
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Thanks for the link. I have a question pertaining to that link. incase of vxlan, is there any additional setting that has to be done? I have only followed the newton installation guide with self service network.external network when created with vxlan or vlan setting doesnt allow vms to ping host

sanjana gravatar imagesanjana ( 2017-05-04 00:19:33 -0500 )edit

Is it possible to achieve the same with linux bridge?

sanjana gravatar imagesanjana ( 2017-05-04 01:03:10 -0500 )edit

I worked only with OVS 2.5/2.6 (RDO Openstack)

dbaxps gravatar imagedbaxps ( 2017-05-04 10:54:38 -0500 )edit

answered 2017-05-03 23:42:46 -0500

First, please try to read the Networking Guide on Here is an overview for busy people:

The Network Managers you mention seem to come from the old Nova-Network service, which was replaced by Neutron roundabout 2013. At Ocata, Nova-Network is obsolete.

Neutron is a framework for implementing virtual networking. The actual implementation is done by so-called plugins, which is a hint that there are many possible ways of setting up your network. The most important plugin implements the core resources network, subnet and port and is therefore called the core plugin. Most often, ML2 is used as the core plugin.

ML2 uses so-called type drivers and mechanism drivers to implement virtual networking. Type drivers implement protocols like VLAN or VXLAN. Mechanism drivers implement the wiring of virtual machines to the network; the most popular mechanisms are LinuxBridge and Openvswitch.

There are two categories of virtual networks: Provider networks directly correspond to physical networks in the datacenter. Usually, provider networks use types Flat or VLAN; I don't know if other types are possible. Tenant networks are entirely virtual and can be implemented with network types VLAN, GRE, VXLAN and the less known Geneve. Provider networks can only be set up by the admin, whereas tenant networks can be created and manipulated by users.

A typical config is a single provider network that is also used to connect the cloud to the internet. Such a provider network is named external. A router then connects tenant networks to the external network.

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I followed the openstack newton instal guide and selected the self-service networks. The type driver there is vxlan. However in Horizon when i create an external network of type vxlan and connect it to my internal network, the instances on my internal network cannot ping to my compute and controller

sanjana gravatar imagesanjana ( 2017-05-04 00:16:20 -0500 )edit

The same setting, works if my external network is configured to be a flat network. I am not sure if its wrong or my setup is incorrect.

sanjana gravatar imagesanjana ( 2017-05-04 00:17:22 -0500 )edit

The install guide does indeed configure VXLAN for the self-service network. However, not for provider networks; I don't think that would work.

How do you create an external network of type vxlan?

Bernd Bausch gravatar imageBernd Bausch ( 2017-05-04 01:47:44 -0500 )edit

I go to admin tab and select networks. If i create a network using provider type "vxlan" if face ssh and access issues

sanjana gravatar imagesanjana ( 2017-05-04 03:25:33 -0500 )edit

I have never heard of a provider network with type VXLAN. I would like to see your network details; run openstack network show on the external network and post the output.

Bernd Bausch gravatar imageBernd Bausch ( 2017-05-04 07:26:32 -0500 )edit

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Asked: 2017-05-03 23:04:40 -0500

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Last updated: May 04 '17