A: The kernel module in upstream Linux 3.3 and later does not include
tunnel virtual ports, that is, interfaces with type "gre",
- "ipsec_gre", "gre64", "ipsec_gre64", "vxlan", or "capwap". It is
+ "ipsec_gre", "gre64", "ipsec_gre64", or "vxlan". It is
possible to create tunnels in Linux and attach them to Open vSwitch
as system devices. However, they cannot be dynamically created
through the OVSDB protocol or set the tunnel ids as a flow action.
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.
can refer to the answer there for more information.
+VXLANs
+-----
+
+Q: What's a VXLAN?
+
+A: VXLAN stands for Virtual eXtensible Local Area Network, and is a means
+ to solve the scaling challenges of VLAN networks in a multi-tenant
+ environment. VXLAN is an overlay network which transports an L2 network
+ over an existing L3 network. For more information on VXLAN, please see
+ the IETF draft available here:
+
+ http://tools.ietf.org/html/draft-mahalingam-dutt-dcops-vxlan-03
+
+Q: How much of the VXLAN protocol does Open vSwitch currently support?
+
+A: Open vSwitch currently supports the framing format for packets on the
+ wire. There is currently no support for the multicast aspects of VXLAN.
+ To get around the lack of multicast support, it is possible to
+ pre-provision MAC to IP address mappings either manually or from a
+ controller.
+
+Q: What destination UDP port does the VXLAN implementation in Open vSwitch
+ use?
+
+A: By default, Open vSwitch will use the assigned IANA port for VXLAN, which
+ is 4789. However, it is possible to configure the destination UDP port
+ manually on a per-VXLAN tunnel basis. An example of this configuration is
+ provided below.
+
+ ovs-vsctl add-br br0
+ ovs-vsctl add-port br0 vxlan1 -- set interface vxlan1
+ type=vxlan options:remote_ip=192.168.1.2 options:key=flow
+ options:dst_port=8472
+
+
Controllers
-----------
projects / cascardo / ovs.git / blobdiff