Merge commit 'origin/citrix'

[sliver-openvswitch.git] / vswitchd / ovs-vswitchd.conf.5.in

diff --git a/vswitchd/ovs-vswitchd.conf.5.in b/vswitchd/ovs-vswitchd.conf.5.in
index 0dbf94d..431e20b 100644 (file)
--- a/vswitchd/ovs-vswitchd.conf.5.in
+++ b/vswitchd/ovs-vswitchd.conf.5.in
@@ -266,6 +266,22 @@ a trunk port, the frame's VLAN tag will be set to \fIvid\fR, replacing
 any existing tag; when it is sent out an implicit VLAN port, the frame
 will not be tagged.  This type of mirroring may be referred to as
 RSPAN.
+.IP
+Please note that mirroring to a VLAN can disrupt a network that
+contains unmanaged switches.  Consider an unmanaged physical switch
+with two ports: port 1, connected to an end host, and port 2,
+connected to an Open vSwitch configured to mirror received packets
+into VLAN 123 on port 2.  Suppose that the end host sends a packet on
+port 1 that the physical switch forwards to port 2.  The Open vSwitch
+forwards this packet to its destination and then reflects it back on
+port 2 in VLAN 123.  This reflected packet causes the unmanaged
+physical switch to replace the MAC learning table entry, which
+correctly pointed to port 1, with one that incorrectly points to port
+2.  Afterward, the physical switch will direct packets destined for
+the end host to the Open vSwitch on port 2, instead of to the end host
+on port 1, disrupting connectivity.  If mirroring to a VLAN is desired
+in this scenario, then the physical switch must be replaced by one
+that learns Ethernet addresses on a per-VLAN basis.
 .ST "Example"
 The following \fBovs\-vswitchd\fR configuration copies all frames received
 on \fBeth1\fR or \fBeth2\fR to \fBeth3\fR.
@@ -507,7 +523,8 @@ the connection to the controller stays down long enough, no packets
 can pass through the switch at all.
 .IP
 The first of these that is set takes effect.
-If the value is \fBstandalone\fR, \fBovs\-vswitchd\fR will take over
+If the value is \fBstandalone\fR, or if neither of these settings
+is set, \fBovs\-vswitchd\fR will take over
 responsibility for setting up
 flows when no message has been received from the controller for three
 times the inactivity probe interval (see above).  In this mode,
@@ -516,9 +533,8 @@ MAC-learning switch.  \fBovs\-vswitchd\fR will continue to retry connecting
 to the controller in the background and, when the connection succeeds,
 it discontinues its standalone behavior.
 .IP
-If this option is set to \fBsecure\fR, or if neither of these settings
-is set, \fBovs\-vswitchd\fR will not set up flows on its own when the
-controller connection fails.
+If this option is set to \fBsecure\fR, \fBovs\-vswitchd\fR will not
+set up flows on its own when the controller connection fails.
 .IP "\fBbridge.\fIname\fB.controller.max-backoff=\fIsecs\fR"
 Sets the maximum time between attempts to connect to the controller to
 \fIsecs\fR, which must be at least 1.  The actual interval between