shared by all bridges of that type. The "ovs-appctl dpif/*"
commands provide similar functionality that is scoped by the bridge.
+Q: I created a GRE port using ovs-vsctl so why can't I send traffic or
+ see the port in the datapath?
+
+A: On Linux kernels before 3.11, the OVS GRE module and Linux GRE module
+ cannot be loaded at the same time. It is likely that on your system the
+ Linux GRE module is already loaded and blocking OVS (to confirm, check
+ dmesg for errors regarding GRE registration). To fix this, unload all
+ GRE modules that appear in lsmod as well as the OVS kernel module. You
+ can then reload the OVS module following the directions in INSTALL,
+ which will ensure that dependencies are satisfied.
+
Quality of Service (QoS)
------------------------
When support for a given OpenFlow version is solidly implemented,
Open vSwitch will enable that version by default.
+Q: Does Open vSwitch support MPLS?
+
+A: Before version 1.11, Open vSwitch did not support MPLS. That is,
+ these versions can match on MPLS Ethernet types, but they cannot
+ match, push, or pop MPLS labels, nor can they look past MPLS labels
+ into the encapsulated packet.
+
+ Open vSwitch versions 1.11, 2.0, and 2.1 have very minimal support
+ for MPLS. With the userspace datapath only, these versions can
+ match, push, or pop a single MPLS label, but they still cannot look
+ past MPLS labels (even after popping them) into the encapsulated
+ packet. Kernel datapath support is unchanged from earlier
+ versions.
+
+ Open vSwitch version 2.2 will be able to match, push, or pop up to
+ 3 MPLS labels. Looking past MPLS labels into the encapsulated
+ packet will still be unsupported. Both userspace and kernel
+ datapaths will be supported, but MPLS processing always happens in
+ userspace either way, so kernel datapath performance will be
+ disappointing.
+
Q: I'm getting "error type 45250 code 0". What's that?
A: This is a Open vSwitch extension to OpenFlow error codes. Open