How to manually configure an Open vSwitch STT tunnel between VMs running on Hyper-V and KVM hosts.

In this post we will explain how to configure manually a Open vSwitch STT tunnel between VMs running on Hyper-V and KVM hosts.

KVM OVS configuration

In this example, KVM1 provides a STT tunnel with local endpoint 14.14.14.1:

  • stt-1 connected to Hyper-V (14.14.14.2) through br-eth3
[email protected]:~$ sudo ovs-vsctl show
82585eef-349c-4573-8d77-91f9602bb535
    Bridge br-int
        fail_mode: secure
        Port br-int
            Interface br-int
                type: internal
        Port "vm1"
            Interface "vm1"
                type: internal
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
    Bridge "br-eth3"
        Port "eth3"
            Interface "eth3"
        Port "br-eth3"
            Interface "br-eth3"
                type: internal
    Bridge br-tun
        fail_mode: secure
        Port "stt-1"
            Interface "stt-1"
                type: stt
                options: {in_key=flow, local_ip="14.14.14.1", out_key=flow, remote_ip="14.14.14.2"}
        Port patch-int
            Interface patch-int
                type: patch
                options: {peer=patch-tun}
        Port br-tun
            Interface br-tun
                type: internal
[email protected]:~$ ifconfig eth3
eth3      Link encap:Ethernet  HWaddr 00:0c:29:25:db:8c  
          inet6 addr: fe80::20c:29ff:fe25:db8c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:40051 errors:0 dropped:0 overruns:0 frame:0
          TX packets:51087 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:6907123 (6.9 MB)  TX bytes:81805610 (81.8 MB)
[email protected]:~$ ifconfig br-eth3
br-eth3   Link encap:Ethernet  HWaddr 00:0c:29:25:db:8c  
          inet addr:14.14.14.1  Bcast:14.14.14.255  Mask:255.255.255.0
          inet6 addr: fe80::d413:1fff:fe62:cdd8/64 Scope:Link
          UP BROADCAST RUNNING  MTU:1500  Metric:1
          RX packets:1377 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1573 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:315330 (315.3 KB)  TX bytes:283030 (283.0 KB)
ubuntu@@ubuntu:~$ ifconfig vm1
vm1       Link encap:Ethernet  HWaddr 6a:d6:1b:77:2d:95  
          inet addr:10.0.0.1  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: fe80::68d6:1bff:fe77:2d95/64 Scope:Link
          UP BROADCAST RUNNING  MTU:1420  Metric:1
          RX packets:506 errors:0 dropped:0 overruns:0 frame:0
          TX packets:768 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:39788 (39.7 KB)  TX bytes:61932 (61.9 KB)

Please note the MTU value on vm1 is set to 1420.

Hyper-V OVS configuration

Let us assume that you have a Hyper-V Virtual Switch of type external bound to the interface port1 called vSwitch.

The following commands will: create an IP-able device called br-port1, add the physical NIC to the bridge called br-port1, enable the device named br-port1, set the IP 14.14.14.2 to br-port1, add a bridge br-int in which we shall add the VMs later on, and will create another bridge with the tunneling information on the port stt-1.

ovs-vsctl.exe add-br br-port1
ovs-vsctl.exe add-port br-port1 port1
Enable-NetAdapter br-port1
New-NetIpAddress -IpAddress 14.14.14.2 -PrefixLength 24 -InterfaceAlias br-port1
ovs-vsctl.exe add-br br-int
ovs-vsctl.exe add-port br-int patch-tun -- set interface patch-tun type=patch options:peer=patch-int
ovs-vsctl.exe add-br br-tun
ovs-vsctl.exe add-port br-tun patch-int -- set interface patch-int type=patch options:peer=patch-tun
ovs-vsctl.exe add-port br-tun stt-1 -- set interface stt-1 type=stt options:local_ip=14.14.14.2 options:remote_ip=14.14.14.1 options:in_key=flow options:out_key=flow

As you can see, all the commands are very familiar if you are used to OVS on Linux.

As introduced before, the main area where the Hyper-V implementation differs from its Linux counterpart is in how virtual machines are attached to a given OVS port. This is easily accomplished by using the Set-VMNetworkAdapterOVSPort PowerShell cmdlet provided with the installer (please refer to part1 for details on installing OVS).

Let us say that we have a Hyper-V virtual machine called “instance-00000003” and that we want to connect it to the Hyper-V OVS switch. All we have to do for each VM network adapter is to connect it to the Hyper-V Virtual Switch named vSwitch as you would normally do, assign it to a given OVS port and create the corresponding ports in OVS:

$vnic = Get-VMNetworkAdapter instance-00000003
Connect-VMNetworkAdapter -VMNetworkAdapter $vnic -SwitchName vSwitch
$vnic | Set-VMNetworkAdapterOVSPort -OVSPortName vm2
ovs-vsctl.exe add-port br-int vm2

Here is how the resulting OVS configuration looks like on Hyper-V:

PS C:\> ovs-vsctl.exe show
a81a54fc-0a3c-4152-9a0d-f3cbf4abc3ca
    Bridge br-int
        Port "vm2"
            Interface "vm2"
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
        Port br-int
            Interface br-int
                type: internal
    Bridge br-tun
        Port "stt-1"
            Interface "stt-1"
                type: stt
                options: {in_key=flow, local_ip="14.14.14.2", out_key=flow, remote_ip="14.14.14.1"}
        Port patch-int
            Interface patch-int
                type: patch
                options: {peer=patch-tun}
        Port br-tun
            Interface br-tun
                type: internal
    Bridge "br-port1"
        Port "port1"
            Interface "port1"
        Port "br-port1"
            Interface "br-port1"
                type: internal

Further control can be accomplished by applying flow rules.

OVS based networking is now fully functional between KVM and Hyper-V hosted virtual machines!

P.S.: Don’t forget to check out part 1 (OpenStack)part 2 (VXLAN) and part 3 (GRE) of this series if you missed them!

This post first appeared on the Cloudbase Solutions blog. Superuser is always interested in community content, email: [email protected].

Cover Photo // CC BY NC