Part 2: Configure Openstack OVSBridge, Network (Neutron), Public and Private Network, Router in Openstack

The important part of networking in the OpenStack cloud is OVS. Open vSwitch is not a part of OpenStack project. However, OVS is used in most implementations of OpenStack clouds. It has also been integrated into many other virtual management systems including OpenQRM, OpenNebula, and oVirt. Open vSwitch can provide support for protocols such as OpenFlow, GRE, VLAN, VXLAN, NetFlow, sFlow, SPAN, RSPAN, and LACP. It can operate in distributed configurations with a central controller.

Open vSwitch by itself consists of several components:

• openswitch_mod.ko: The module plays the role of ASIC (application-specific integrated circuit) in hardware switches. This module is an engine of traffic processing.
• Daemon ovs-vswitchd : The daemon is in charge of management and logic for data transmitting.
• Daemon ovsdb-server : The daemon is used for the internal database. It also provides RPC (remote procedure call) interfaces to one or more Open vSwitch databases (OVSDBs).

To check the version of openvswitch installed

Step 1: Configure OVSBridge on the Controller

OpenStack Neutron Services and Their Placement

To do the below changes make sure openvswitch is installed on your setup

Navigate to the path of your interface configuration files

Copy the configuration of your eth0 as below (The name of the interface may vary depending upon the environment)

Make the highlighted changes in your ifcfg-br-ex

Next make the below changes in your ifcfg-eth0 file and remove all the unwanted entries

Restart your network services

Once done validate your new configuration, the IP Address must be now assigned to "br-ex" device instead on eth0

Validate the bridge connection

As you can see, three bridges exist:

• Integration bridge (br-int): There is a single integration bridge on each node. This bridge acts as a virtual switch where all virtual network cards from all virtual machines are connected. OVS Neutron agent automatically creates the integration bridge. The integration bridge "br-int", tage and untags VLAN traffic that originated from the instance and traffic destined for the instance
• External bridge (br-ex): This bridge is for interconnection with external networks. In o
• Tunnel bridge (br-tun): This bridge is a virtual switch like br-int . It connects the GRE and VXLAN tunnel endpoints. The tunneling bridge "br-tun" translates the traffic that was received by the integration bridge "br-int" into VXLAN tunnels.

Here is an example of the code from a config file for neutron-openvswitch-agent

Step 2: Create Internal Network

Now we are ready to create internal network which will be assigned to the instances

Login to your horizon dashboard

Navigate to Project -> Network -> Networks

Click on "Create Network"

Fill the provided details

Network Name   : internal_network
Admin State  : UP
Create Subnet : Checked

Click on Next

Subnet Name  : int_subnet
Network Address : 192.168.100.0/24
IP Version            : IPv4
Gateway IP : 192.168.100.254

Subnet Details

DHCP Enable   : Checked
DNS Servers  : 10.43.138.12

Click on "Create"

So our network is successfully created as you see below

Step 3: Create External Network

Now we need an external network which can be used as Floating IP to connect to the instance.

Login to your horizon dashboard

Navigate to Project -> Network -> Networks



Click on "Create Network"

Fill the provided details
Network Name  : external_network
Admin State  : UP
Create Subnet :  Checked

Click on Next
Subnet Name  : ext_subnet
Network Address : 192.168.122.0/24
IP Version  : IPv4
Gateway IP  : 192.168.122.1

Subnet Details

DHCP Enable  : Checked
DNS Servers  : 10.43.138.12

Click on "Create"

Now our network is created but currently it will work only as internal network unless we explicitly assign it as "external"

So Navigate to Admin -> Networks

Here you will see the list of available networks which we created as shown below

Next select the check box of the "external-network" and click on "Edit Network"

Next select the check box as shown below to make this as external network (public) and click on "Save Changes"

You can also validate this from your CLI

To get more details about the network we created

Now the internal network

Step 4: Create Routers

Whether using IPv4 or Ipv6, network traffic needs to move from host to host and network to network. Each host has a routing table, which tells it how to route traffic for particular networks. The routing table entries will list a destination network, which interface to send out the traffic out, and the IP address of any intermediate router that is required to relay the message to its final destination. The routing table entry which matches the destination of the network traffic is used to route it. If two entries match, the one with the longest prefix is used.

In order for instance to communicate with any external subnet, a router must be deployed. red Hat Openstack platform provides routing by using an SDN- based virtual router. Similar to physulcal routers, SDN-based virtual routers require one subnet per interface. Traffic received by the router use the router's default gateway as the next hop. The default gateway uses a virtual bridge to route the traffic to an external network. Each router has many interfaces that conncet to subnets and one gateway that connects to a network.

To create a router, in Horizon

Navigate to Project -> Network -> Routers

Click on "Create Router"

Provide the below details
Router name : test-router
Admin State : UP
External Network  : external_network (Select the public network which you created above at step 3)

And click on "Create Router"

Next click on the router name i.e. "test-router" for us
It will show you the router details under "Overview"
Navigate to "Interfaces" TAB and click on "Add Interface"

Next select the internal network which we created from the drop down menu for "Subnet"

You can leave the IP Address section blank as we have enabled DHCP so the IP Address will be automatically allocated to us.

Once done click on "Add Interface"

We are done with our Network Setup.