Preparing Centos Preparing Centos Server For Neutron
This article describes how prepare a CentOS physical server to be added as a host to Platform9 Managed OpenStack (PMO) cloud.
Note
For a description of PMO networking concepts, refer to the Networking Basic Concepts tutorial Networking. Refer to PMO prerequisites for Linux/KVM for systems requirements and supported CentOS Operating System versions.
Supported Operating System Version
Platform9 Managed OpenStack supports CentOS 7+ (64-bit).
Step 1 - Install CentOS Operating System
Make sure that your server is configured appropriately with access to storage and physical networking. Download and install CentOS on your physical server. You can download CentOS distributions from here: http://wiki.centos.org/Download
Note
We recommend installing the minimal CentOS operating system. Platform9 agents are prepared to pull in any required package dependencies and get them installed on your server to prepare it to be part of OpenStack. This includes any libvirt/KVM package dependencies.
It’s usually a good practice to get your system up to date with regard to the latest patches and updates.
sudo yum -y updateStep 2 - Ensure Virtualization is Enabled
Ensure that virtualization is enabled for your server by checking your server’s BIOS settings. If disabled, enable virtualization for the server to be able to act as a hypervisor within Platform9 Managed OpenStack.
Step 3 - Ensure the System Clock is Synchronized
Your host will fail to authenticate with Platform 9 services if its date / time settings are incorrect. Type date to verify that the current date and time are correct. If they aren’t, then one possible fix is to enable the network time protocol daemon service:
The following image (Figure 1) represents three hypervisors connected in a Managed OpenStack Neutron network.
Note
There are no separate network nodes in a Distributed Virtual Routing (DVR) network.
Step 4 - Set SELinux to permissive
This is required for Open vSwitch (OVS) to be able to manage networking.
Run the following commands to set SELinux to permissive.
Step 5 - Disable Firewalld and NetworkManager
This is required for KVM and OVS to be able to create iptables rules directly without firewalld getting in the way.
Run the following commands to disable firewalld and NetworkManager.
Step 6 - Enable Network
Run the following command to enable network.
Step 7 - Load the modules needed for Neutron
Run the following commands to load the modules needed for Neutron.
Step 8 - Add sysctl options
Run the following commands to add sysctl options.
Step 9 - Add the Platform9 YUM Repo
Run the following command to install the Platform9 YUM repository.
For Platform9 releases upto and including 4.4:
Step 10 - Install Open vSwitch
Run the following command to get a list of available Open vSwitch versions.
If you wish to install an available older version, run the following command.
Alternatively, if you wish to install the latest version, run the following command.
Step 11 - Enable and start Open vSwitch
Run the following commands to enable and start Open vSwitch.
Step 12 - Install QEMU KVM EV
Run the following commands to install QEMU KVM EV
Step 13 - Install Router Advertisement Daemon
Run the following command to install radvd
Step 14 - Configure physical interfaces
Info
Figure 1 in the article represents a sample Neutron network configuration. Steps 10 through 14 are based on the configuration shown in Figure 1 from the article. Steps 10 through 14 describe the configuration of physical interfaces into a Linux bond, addition of VLAN interfaces for management, VXLAN/GRE network traffic and storage. You may or may not require one or more of these steps. The steps to follow would be based on your Neutron network configuration. For instance, if you do not plan on using VXLAN/GRE, you can skip the step to set up VXLAN/GRE tunneling interface.
We assume the interface names to be eth0 and eth1.
Substitute eth0 and eth1 with the appropriate interface names per your setup, when you run the commands given for this step.
Similarly, we are assuming an MTU of 9000 - VXLAN requires an MTU of at least 1600.
Make sure all physical switches are configured to handle the MTU of 1600 or you might have problems.
Run the following commands to configure physical interfaces.
/etc/sysconfig/network-scripts/ifcfg-eth0
/etc/sysconfig/network-scripts/ifcfg-eth1
Step 15 - Set up the Bond interface
Note
We are assuming bonding type=4 (LACP) refer to CentOS Bonding Types to learn more.
Run the following commands to set up the bond interface.
/etc/sysconfig/network-scripts/ifcfg-bond0
Step 16 - Setup the Management interface
Note
We are assuming VLAN 101 for the Management network. Replace it with the correct VLAN ID per your setup. We are assuming subnet 192.0.2.0/24 for Management. Replace it with the correct subnet per your setup.
/etc/sysconfig/network-scripts/ifcfg-bond0.101
Step 17 - Setup the VXLAN/GRE tunneling interface (Optional)
Note
We are assuming VLAN 102 for VXLAN/GRE tunneling. Please use the correct VLAN per your setup. We are assuming subnet 198.51.100.0/24 for VXLAN/GRE tunneling. Please use the correct subnet per your setup.
Run the following commands to VXLAN/GRE tunneling interface.
/etc/sysconfig/network-scripts/ifcfg-bond0.102
Step 18 - Setup the Storage interface (Optional)
Note
We are assuming VLAN 103 for the storage network. Replace it with the VLAN per your setup. We are assuming subnet 203.0.113.0/24 for the storage network. Replace it with the subnet per your setup.
Run the following commands to set up the storage interface.
/etc/sysconfig/network-scripts/ifcfg-bond0.103
Step 19 - Restart Networking
Warning
Make sure you have console access to your host. You will be disconnected if the configuration is incorrect.
Run the following command to restart the network service.
Step 20 - Create OVS Bridges
The number of OVS bridges you need will determine on how many physical networks your hosts connect to, and what types of networks you will be creating.
Let us look at some basic networking terminology before creating the bridges.
An access port represents a single flat physical network or VLAN, and will carry untagged traffic.
A trunk port logically groups together multiple VLANs. An 802.1Q QTag header will be inserted into the Ethernet frame for all VLAN traffic. All untagged traffic is implicitly assigned a default, native VLAN per your data center’s switch configuration.
Each physical network corresponds to a trunk or access port (an individual NIC, or a pair of NICs bonded together) on the host. An Open vSwitch bridge must be created for each physical network.
When configuring Platform9 OpenStack’s Networking Config, each physical network is given a Label as a name, and that label mapped to a particular OVS bridge on the host during host authorization.
Let us look at two different examples of common host networking setups.
Example 1: Non-DVR setup with one external flat network, and trunk port for VLAN traffic
The following figure (Figure 2) represents a non-DVR network setup with an external flat network, and a trunk port for VLAN traffic.
In the above figure 2, the network has a trunk port consisting of eth0 and eth1 in a bond that will carry our VLAN based networks(tenant, provider), as well as a dedicated port (eth2) that connects to a separate external network. This is a legacy, non-DVR setup where external connectivity and L3 capability is only on network nodes. Nodes that are hypervisors only carry the tenant network traffic, and need just 1 OVS bridge.
Run the following commands to add OVS bridges on the hypervisors. The steps below assume eth0/eth1 have already been configured in a Linux bond called bond0. Please refer to steps 10-15 to set up your physical interfaces.
On our network node, we have a separate NIC that connects to a different physical network. For this, we need a separate OVS bridge.
Run the following commands to add an OVS bridge.
Example 2: DVR setup with a pair of NICs in a bond
The following figure (Figure 3) represents a DVR network setup with a pair of NICs in a bond.
In the DVR setup seen in figure 3 above, every host has external L3 connectivity. Here, we only have a pair of NICs in a bond. Therefore this OVS Bridge can only support one Flat (untagged) network, and as many VLAN-tagged networks as your networking infrastructure allows. There are multiple external networks that are VLAN-based, in addition to our tenant networks.
Run the following commands to add an OVS bridge on all hosts.
Note
The steps below assume eth0/eth1 have already been configured in a Linux bond called “bond0”. Refer to steps 10-14 to set up your physical interfaces.
At this point your CentOS server is ready to be added as a hypervisor to Platform9 Managed OpenStack (PMO).
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