| | 46 | In order to configure the OVS switch, we first login to the host that will be used as an !OpenFlow switch. |
| | 47 | |
| | 48 | Depending on which tool and OS you are using there is a slightly different process for logging in. If you don't know how to SSH to your reserved hosts learn [wiki:HowTo/LoginToNodes how to login.] |
| | 49 | |
| | 50 | === 2a. Configure the Software Switch (OVS Window) === |
| | 51 | |
| | 52 | Now that you are logged in, we need first to configure OVS. To save time in this tutorial, we have already started OVS and we have added an Ethernet bridge that will act as our software switch. Try the following to show the configured bridge: |
| | 53 | {{{ |
| | 54 | sudo ovs-vsctl list-br |
| | 55 | }}} |
| | 56 | You should see only one bridge `br0`. Now we need to add the interfaces to this bridge that will act as the ports of the software switch. |
| | 57 | |
| | 58 | {{{ |
| | 59 | #!html |
| | 60 | <table border="0"> |
| | 61 | <tr > |
| | 62 | <td width = "500"> |
| | 63 | <ol> |
| | 64 | <li>List all the interfaces of the node |
| | 65 | <ul> <li> <code>ifconfig</code> </ul><br/> |
| | 66 | Write down the interface names that correspond to the connections to your hosts. This information will be needed for one of the exercises. The correspondence is: |
| | 67 | <ul> |
| | 68 | <li> Interface with IP ''10.10.1.11'' to host1 - ethX</li> |
| | 69 | <li> Interface with IP ''10.10.1.12'' to host2 - ethY</li> |
| | 70 | <li> Interface with IP ''10.10.1.13'' to host3 - ethZ</li> |
| | 71 | </ul></li> |
| | 72 | </li> <br/> |
| | 73 | <li> Be careful <b> not to bring down eth0</b>. This is the control interface, if you bring that interface down you <b> won't be able to login</b> to your host. For all interfaces other than <code>eth0</code> and <code> l0</code>, remove the IP from the interfaces (your interface names may vary): <br/> |
| | 74 | <ul><li> <code> sudo ifconfig ethX 0 </code> </li></ul> |
| | 75 | <ul><li> <code> sudo ifconfig ethY 0 </code> </li></ul> |
| | 76 | <ul><li> <code> sudo ifconfig ethZ 0 </code> </li></ul> |
| | 77 | <li> Add all the data interfaces to your switch (bridge):Be careful <b> not to add interface eth0</b>. This is the control interface. The other three interfaces are your data interfaces. (Use the same interfaces as you used in the previous step.) |
| | 78 | <ul><li> <code> sudo ovs-vsctl add-port br0 ethX </code> </li></ul> |
| | 79 | <ul><li> <code> sudo ovs-vsctl add-port br0 ethY </code> </li></ul> |
| | 80 | <ul><li> <code> sudo ovs-vsctl add-port br0 ethZ </code> </li></ul> |
| | 81 | </li> |
| | 82 | </ol> |
| | 83 | </td> |
| | 84 | <td> |
| | 85 | <img border="0" src="http://groups.geni.net/geni/attachment/wiki/GENIExperimenter/Tutorials/OpenflowOVS/Graphics/ovs-interfaces.jpg?format=raw" alt="Login information for a VM" height="250" title="Login information for a VM" /> </a> |
| | 86 | </td> |
| | 87 | </tr> |
| | 88 | </table> |
| | 89 | }}} |
| | 90 | |
| | 91 | Congratulations! You have configured your software switch. To verify the three ports configured run: |
| | 92 | {{{ |
| | 93 | sudo ovs-vsctl list-ports br0 |
| | 94 | }}} |
| | 95 | |
| | 96 | === 2c. Point your switch to a controller === |
| | 97 | |
| | 98 | In the controller window, find the control interface IP of your controller, use ''ifconfig'' and note down the IP address of `eth0`. |
| | 99 | |
| | 100 | An !OpenFlow switch will not forward any packet unless instructed by a controller. Basically the forwarding table is empty, until an external controller inserts forwarding rules. The !OpenFlow controller communicates with the switch over the control network and it can be anywhere in the Internet as long as it is reachable by the OVS host. |
| | 101 | |
| | 102 | In order to point our software !OpenFlow switch to the controller, in the ''ovs'' window, run: |
| | 103 | {{{ |
| | 104 | sudo ovs-vsctl set-controller br0 tcp:<controller_ip>:6633 |
| | 105 | }}} |
| | 106 | |
| | 107 | ==== `standalone` vs `secure` mode ==== |
| | 108 | |
| | 109 | The !OpenFlow controller is responsible for setting up all flows on the switch, which means that when the controller is not running there should be no packet switching at all. Depending on the setup of your network, such a behavior might not be desired. It might be best that when the controller is down, the switch should default back to being a learning layer 2 switch. In other circumstances however this might be undesirable. In OVS this is a tunable parameter, called `fail-safe-mode` which can be set to the following parameters: |
| | 110 | * `standalone` [default]: in this case OVS will take responsibility for forwarding the packets if the controller fails |
| | 111 | * `secure`: in this case only the controller is responsible for forwarding packets, and if the controller is down all packets are dropped. |
| | 112 | |
| | 113 | In OVS when the parameter is not set it falls back to the `standalone` mode. For the purpose of this tutorial we will set the `fail-safe-mode` to `secure`, since we want to be the ones controlling the forwarding. Run: |
| | 114 | {{{ |
| | 115 | sudo ovs-vsctl set-fail-mode br0 secure |
| | 116 | }}} |
| | 117 | You can verify your OVS settings by issuing the following: |
| | 118 | |
| | 119 | {{{ |
| | 120 | sudo ovs-vsctl show |
| | 121 | }}} |
