It should build against almost any kernel, certainly against 2.6.18
and later.
+Q: Should userspace or kernel be upgraded first to minimize downtime?
+
+ In general, the Open vSwitch userspace should be used with the
+ kernel version included in the same release or with the version
+ from upstream Linux. However, when upgrading between two releases
+ of Open vSwitch it is best to migrate userspace first to reduce
+ the possbility of incompatibilities.
+
Q: What features are not available in the Open vSwitch kernel datapath
that ships as part of the upstream Linux kernel?
alternative, Open vSwitch supports mirroring to a GRE tunnel (see
above).
+Q: Why are there so many different ways to dump flows?
+
+A: Open vSwitch uses different kinds of flows for different purposes:
+
+ - OpenFlow flows are the most important kind of flow. OpenFlow
+ controllers use these flows to define a switch's policy.
+ OpenFlow flows support wildcards, priorities, and multiple
+ tables.
+
+ When in-band control is in use, Open vSwitch sets up a few
+ "hidden" flows, with priority higher than a controller or the
+ user can configure, that are not visible via OpenFlow. (See
+ the "Controller" section of the FAQ for more information
+ about hidden flows.)
+
+ - The Open vSwitch software switch implementation uses a second
+ kind of flow internally. These flows, called "exact-match"
+ or "datapath" or "kernel" flows, do not support wildcards or
+ priorities and comprise only a single table, which makes them
+ suitable for caching. OpenFlow flows and exact-match flows
+ also support different actions and number ports differently.
+
+ Exact-match flows are an implementation detail that is
+ subject to change in future versions of Open vSwitch. Even
+ with the current version of Open vSwitch, hardware switch
+ implementations do not necessarily use exact-match flows.
+
+ Each of the commands for dumping flows has a different purpose:
+
+ - "ovs-ofctl dump-flows <br>" dumps OpenFlow flows, excluding
+ hidden flows. This is the most commonly useful form of flow
+ dump. (Unlike the other commands, this should work with any
+ OpenFlow switch, not just Open vSwitch.)
+
+ - "ovs-appctl bridge/dump-flows <br>" dumps OpenFlow flows,
+ including hidden flows. This is occasionally useful for
+ troubleshooting suspected issues with in-band control.
+
+ - "ovs-dpctl dump-flows [dp]" dumps the exact-match flow table
+ entries for a Linux kernel-based datapath. In Open vSwitch
+ 1.10 and later, ovs-vswitchd later merges multiple switches
+ into a single datapath, so it will show all the flows on all
+ your kernel-based switches. This command can occasionally be
+ useful for debugging.
+
+ - "ovs-appctl dpif/dump-flows <br>", new in Open vSwitch 1.10,
+ dumps exact-match flows for only the specified bridge,
+ regardless of the type.
+
Configuration Problems
----------------------
point, so the same problems will show up with the Linux bridge or
any other way to do bridging.
+Q: I can't seem to add my PPP interface to an Open vSwitch bridge.
+
+A: PPP most commonly carries IP packets, but Open vSwitch works only
+ with Ethernet frames. The correct way to interface PPP to an
+ Ethernet network is usually to use routing instead of switching.
+
Q: Is there any documentation on the database tables and fields?
A: Yes. ovs-vswitchd.conf.db(5) is a comprehensive reference.
git://git.onelab.eu / sliver-openvswitch.git / blobdiff