{"id":130,"date":"2013-09-20T20:01:07","date_gmt":"2013-09-20T18:01:07","guid":{"rendered":"http:\/\/www.opencloudblog.com\/?p=130"},"modified":"2013-09-23T20:14:34","modified_gmt":"2013-09-23T18:14:34","slug":"openvswitch-port-usage-on-linux","status":"publish","type":"post","link":"https:\/\/www.opencloudblog.com\/?p=130","title":{"rendered":"Openvswitch – Port Usage on Linux"},"content":{"rendered":"

In this post I show the basic commands for the openvswitch.\u00a0You should have at least openvswitch 1.9 installed. This is the case, if you are running Ubuntu 13.04.<\/p>\n

Preparation<\/h1>\n

In this blog, I show more than the basic commands. We use Linux network namespaces to show also the usage on the ip layer. The first step is to create two linux network namespaces (you must be root):<\/p>\n

# create two network namespaces\r\nip netns add ns1\r\nip netns add ns2\r\n\r\n# bring up the loopback interfaces of the namespaces\r\nip netns exec ns1 ip link set dev lo up\r\nip netns exec ns2 ip link set dev lo up<\/pre>\n
Next, \u00a0we need three console sessions. One for each network namespace (use ip netns exec ns <x> bash to get into the namespace) and one for the non namespace config. I recommend, that you change the prompt for each session – it \u00a0helps a lot, that you always knows, where you are.<\/p>\n
#\r\n# MAIN bash \r\n#\r\nexport PS1=\"Main>\"\r\n#\r\n# Console for Network Namespace ns1\r\n#\r\nip netns exec ns1 bash\r\nexport PS1=\"NS 1>\"\r\n#\r\n# Console in Network Namespace ns2\r\n#\r\nip netns exec ns2 bash\r\nexport PS1=\"NS 2>\"<\/pre>\n
\u00a0Create a Switch (bridge)<\/h1>\n
The next step is to create a new virtual switch (or bridge). Use the following command in the Main console:<\/p>\n
# create a new virtual switch\r\novs-vsctl add-br testsw1\r\n\r\n# check using\r\novs-vsctl show\r\n\r\n# the output will look like\r\n9ddae96d-0cc4-4c17-98c2-7ffe3f4f6226             <==== this is the UUID of the running openvswitch\r\n    Bridge testsw1                               <==== this is a running virtual switch instance\r\n        Port testsw1                             \r\n            Interface testsw1                    <==== By default, each virtual switch gets an internal interface      \r\n                type: internal                         internal interface == this is a interface seen by Linux\r\n    ovs_version: \"1.9.0\"                         <==== the version of the openvswitch software running<\/pre>\n
By default, each virtual switch (=bridge), which has been created, gets one „internal port“<\/em> assigned. These internal ports are seen by the Linux OS. Type „ip link“ in the Main console and you get:<\/p>\n
19: testsw1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT \r\n    link\/ether ae:fd:bb:27:2b:43 brd ff:ff:ff:ff:ff:ff<\/pre>\n
You can use this interface in the same way as all other Linux interfaces. Assign IP addresses to it or put IP access lists on it (iptables). We will ignore this interface.<\/p>\n
An openvswitch bridge is not only a simple bridge, it’s a full blown software switch with<\/p>\n