Host network configuration

Installation of OpenStack using an orchestration and configuration tool such as Ansible performs a lot of tasks that would otherwise have to be undertaken manually. However, we can only use an orchestration tool if the servers we are deploying to are configured in a consistent way and described to Ansible.

The following section will describe a typical server setup that uses two sets of active/passive bonded interfaces for use by OpenStack. Ensure that these are cabled appropriately.

We assume that the following physical network cards are installed in each of the servers; adjust them to suit your environment:

• p2p1 and p2p2

• p4p1 and p4p2

We assume that the host network is currently using p2p1. The host network is the basic network that each of the servers currently resides on, and it allows you to access each one over SSH. It is assumed that this network also has a default gateway configured, and allows internet access. There should be no other networks required at this point as the servers are currently unconfigured and are not running OpenStack services.

At the end of this section, we will have created the following bonded interfaces:

• bond0: This consists of the physical interfaces p2p1 and p4p1. The bond0 interface will be used for host, OpenStack management, and storage traffic.

• bond1: This consists of the physical interfaces p2p2 and p4p2. The bond1 interface will be used for Neutron networking within OpenStack.

We will have created the following VLAN tagged interfaces:

• bond0.236: This will be used for the container network

• bond0.244: This will be used for the storage network

• bond1.240: This will be used for the VXLAN tunnel network

And the following bridges:

• br-mgmt: This will use the bond0.236 VLAN interface, and will be configured with an IP address from the 172.29.236.0/24 range.

• br-storage: This will use the bond0.244 VLAN interface, and will be configured with an IP address from the 172.29.244.0/24 range.

• br-vxlan: This will use the bond1.240 VLAN interface, and will be configured with an IP address from the 172.29.240.0/24 range.

• br-vlan: This will use the untagged bond1 interface, and will not have an IP address configured.

Note

Tip: Ensure that your subnets are large enough to support your current requirements as well as future growth!

The following diagram shows the networks, interfaces, and bridges set up before we begin our installation of OpenStack:

Getting ready

We assume that each server has Ubuntu 16.04 installed.

Log in, as root, onto each server that will have OpenStack installed.

How to do it…

Configuration of the host's networking, on a Ubuntu system, is performed by editing the /etc/network/interfaces file.

1. First of all, ensure that we have the right network packages installed on each server. As we are using VLANs and Bridges, the following packages must be installed:

           apt update
           apt install vlan bridge-utils
   

2. Now edit the /etc/network/interfaces file on the first server using your preferred editor:

           vi /etc/network/interfaces
   

3. We will first configure the bonded interfaces. The first part of the file will describe this. Edit this file so that it looks like the following to begin with:

       # p2p1 + p4p1 = bond0 (used for host, container and storage)
       auto p2p1
       iface p2p1 inet manual
         bond-master bond0
         bond-primary p2p1
       auto p4p1
       iface p4p1 inet manual
         bond-master bond0
       # p2p2 + p4p2 = bond1 (used for Neutron and Storage Replication)
       auto p2p2
       iface p2p2 inet manual
         bond-master bond1
         bond-primary p2p2
       auto p4p2
       iface p4p2 inet manual
         bond-master bond1

4. Now we will configure the VLAN interfaces that are tagged against these bonds. Continue editing the file to add in the following tagged interfaces. Note that we are not assigning IP addresses to the OpenStack bonds just yet:

       # We're using bond0 on a native VLAN for the 'host' network.
       # This bonded interface is likely to replace the address you
       # are currently using to connect to this host.
       auto bond0
       iface bond0 inet static
         address 192.168.100.11
         netmask 255.255.255.0
         gateway 192.168.100.1
         dns-nameserver 192.168.100.1 # Update to suit/ensure you can resolve DNS
       auto bond0.236  # Container VLAN
       iface bond0.236  inet manual
       auto bond1.240  # VXLAN Tunnel VLAN
       iface bond1.240  inet manual
       auto bond0.244  # Storage (Instance to Storage) VLAN
       iface bond0.244  inet manual

   Note

   Tip: Use appropriate VLANs as required in your own environment. The VLAN tags used here are for reference only.

   Ensure that the correct VLAN tag is configured against the correct bonded interface. bond0 is for host-type traffic, bond1 is predominantly for Neutron-based traffic, except for storage nodes, where it is then used for storage replication.

5. We will now create the bridges, and place IP addresses on here as necessary (note that br-vlan does not have an IP address assigned). Continue editing the same file and add in the following lines:

   # Container bridge (br-mgmt)
   auto br-mgmt
   iface br-mgmt inet static
     address 172.29.236.11
     netmask 255.255.255.0
     bridge_ports bond0.236        
     bridge_stp off
   # Neutron's VXLAN bridge (br-vxlan)
   auto br-vxlan
   iface br-vxlan inet static
     address 172.29.240.11
     netmask 255.255.255.0
     bridge_ports bond1.240       
     bridge_stp off
   # Neutron's VLAN bridge (br-vlan)
   auto br-vlan
   iface br-vlan inet manual
     bridge_ports bond1
     bridge_stp off
   # Storage Bridge (br-storage)
   auto br-storage
   iface br-storage inet static
     address 172.29.244.11
     netmask 255.255.255.0
     bridge_ports bond0.244
     bridge_stp off

   Note

   These bridge names are referenced in the OpenStack-Ansible configuration file, so ensure you name them correctly.

   Be careful in ensuring that the correct bridge is assigned to the correct bonded interface.

6. Save and exit the file, then issue the following command:

   restart networking
   

7. As we are configuring our OpenStack environment to be as highly available as possible, it is suggested that you also reboot your server at this point to ensure the basic server, with redundant networking in place, comes back up as expected:

   reboot
   

8. Now repeat this for each server on your network.

9. Once all the servers are done, ensure that your servers can communicate with each other over these newly created interfaces and subnets. A test like the following might be convenient:

   apt install fping
   fping -a -g 172.29.236.0/24
   fping -a -g 172.29.240.0/24
   fping -a -g 172.29.244.0/24
   

Note

Tip: We also recommend that you perform a network cable unplugging exercise to ensure that the failover from one active interface to another is working as expected.

How it works…

We have configured the physical networking of our hosts to ensure a good known state and configuration for running OpenStack. Each of the interfaces configured here is specific to OpenStack—either directly managed by OpenStack (for example, br-vlan) or used for inter-service communication (for example, br-mgmt). In the former case, OpenStack utilizes the br-vlan bridge and configures tagged interfaces on bond1 directly.

Note that the convention used here, of VLAN tag ID using a portion of the subnet, is only to highlight a separation of VLANs to specific subnets (for example, bond0.236 is used by the 172.29.236.0/24 subnet). This VLAN tag ID is arbitrary, but must be set up in accordance with your specific networking requirements.

Finally, we performed a fairly rudimentary test of the network. This gives you the confidence that the network configuration that will be used throughout the life of your OpenStack cloud is fit for purpose and gives assurances in the event of a failure of a cable or network card.