Implement new "VLAN splinters" feature.

[openvswitch] / vswitchd / vswitch.xml

diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index 8eba5cbf6be7a6c9e3b3b370252373e53963ab49..a467be4e327ccfceedba37c21b037ee38f9f67ce 100644 (file)
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -1768,6 +1768,73 @@
       </column>
     </group>
 
+    <group title="VLAN Splinters">
+      <p>
+       The ``VLAN splinters'' feature increases Open vSwitch compatibility
+       with buggy network drivers in old versions of Linux that do not
+       properly support VLANs when VLAN devices are not used, at some cost
+       in memory and performance.
+      </p>
+
+      <p>
+       When VLAN splinters are enabled on a particular interface, Open vSwitch
+       creates a VLAN device for each in-use VLAN.  For sending traffic tagged
+       with a VLAN on the interface, it substitutes the VLAN device.  Traffic
+       received on the VLAN device is treated as if it had been received on
+        the interface on the particular VLAN.
+      </p>
+
+      <p>
+        VLAN splinters consider a VLAN to be in use if:
+      </p>
+
+      <ul>
+        <li>
+          The VLAN is listed within the <ref table="Port" column="trunks"/>
+          column of the <ref table="Port"/> record of an interface on which
+          VLAN splinters are enabled.
+
+          An empty <ref table="Port" column="trunks"/> does not influence the
+          in-use VLANs: creating 4,096 VLAN devices is impractical because it
+          will exceed the current 1,024 port per datapath limit.
+        </li>
+
+        <li>
+          An OpenFlow flow within any bridge matches the VLAN.
+        </li>
+      </ul>
+
+      <p>
+        The same set of in-use VLANs applies to every interface on which VLAN
+        splinters are enabled.  That is, the set is not chosen separately for
+        each interface but selected once as the union of all in-use VLANs based
+        on the rules above.
+      </p>
+
+      <p>
+        It does not make sense to enable VLAN splinters on an interface for an
+        access port, or on an interface that is not a physical port.
+      </p>
+
+      <p>
+       VLAN splinters are deprecated.  When broken device drivers are no
+       longer in widespread use, we will delete this feature.
+      </p>
+
+      <column name="other_config" key="enable-vlan-splinters"
+              type='{"type": "boolean"}'>
+        <p>
+          Set to <code>true</code> to enable VLAN splinters on this interface.
+          Defaults to <code>false</code>.
+        </p>
+
+        <p>
+          VLAN splinters increase kernel and userspace memory overhead, so do
+          not use them unless they are needed.
+        </p>
+      </column>
+    </group>
+
     <group title="Common Columns">
       The overall purpose of these columns is described under <code>Common
       Columns</code> at the beginning of this document.