may not be transmitted.
+Basic Configuration
+-------------------
+
+Q: How do I configure a port as an access port?
+
+A: Add "tag=VLAN" to your "ovs-vsctl add-port" command. For example,
+ the following commands configure br0 with eth0 as a trunk port (the
+ default) and tap0 as an access port for VLAN 9:
+
+ ovs-vsctl add-br br0
+ ovs-vsctl add-port br0 eth0
+ ovs-vsctl add-port br0 tap0 tag=9
+
+ If you want to configure an already added port as an access port,
+ use "ovs-vsctl set", e.g.:
+
+ ovs-vsctl set port tap0 tag=9
+
+Q: How do I configure a port as a SPAN port, that is, enable mirroring
+ of all traffic to that port?
+
+A: The following commands configure br0 with eth0 and tap0 as trunk
+ ports. All traffic coming in or going out on eth0 or tap0 is also
+ mirrored to tap1; any traffic arriving on tap1 is dropped:
+
+ ovs-vsctl add-br br0
+ ovs-vsctl add-port br0 eth0
+ ovs-vsctl add-port br0 tap0
+ ovs-vsctl add-port br0 tap1 \
+ -- --id=@p get port tap1 \
+ -- --id=@m create mirror name=m0 select-all=true output-port=@p \
+ -- set bridge br0 mirrors=@m
+
+ To later disable mirroring, run:
+
+ ovs-vsctl clear bridge br0 mirrors
+
+Q: How do I configure a VLAN as an RSPAN VLAN, that is, enable
+ mirroring of all traffic to that VLAN?
+
+A: The following commands configure br0 with eth0 as a trunk port and
+ tap0 as an access port for VLAN 10. All traffic coming in or going
+ out on tap0, as well as traffic coming in or going out on eth0 in
+ VLAN 10, is also mirrored to VLAN 15 on eth0. The original tag for
+ VLAN 10, in cases where one is present, is dropped as part of
+ mirroring:
+
+ ovs-vsctl add-br br0
+ ovs-vsctl add-port br0 eth0
+ ovs-vsctl add-port br0 tap0 tag=10
+ ovs-vsctl \
+ -- --id=@m create mirror name=m0 select-all=true select-vlan=10 \
+ output-vlan=15 \
+ -- set bridge br0 mirrors=@m
+
+ To later disable mirroring, run:
+
+ ovs-vsctl clear bridge br0 mirrors
+
+ Mirroring to a VLAN can disrupt a network that contains unmanaged
+ switches. See ovs-vswitchd.conf.db(5) for details. Mirroring to a
+ GRE tunnel has fewer caveats than mirroring to a VLAN and should
+ generally be preferred.
+
+Q: Can I mirror more than one input VLAN to an RSPAN VLAN?
+
+A: Yes, but mirroring to a VLAN strips the original VLAN tag in favor
+ of the specified output-vlan. This loss of information may make
+ the mirrored traffic too hard to interpret.
+
+ To mirror multiple VLANs, use the commands above, but specify a
+ comma-separated list of VLANs as the value for select-vlan. To
+ mirror every VLAN, use the commands above, but omit select-vlan and
+ its value entirely.
+
+ When a packet arrives on a VLAN that is used as a mirror output
+ VLAN, the mirror is disregarded. Instead, in standalone mode, OVS
+ floods the packet across all the ports for which the mirror output
+ VLAN is configured. (If an OpenFlow controller is in use, then it
+ can override this behavior through the flow table.) If OVS is used
+ as an intermediate switch, rather than an edge switch, this ensures
+ that the RSPAN traffic is distributed through the network.
+
+ Mirroring to a VLAN can disrupt a network that contains unmanaged
+ switches. See ovs-vswitchd.conf.db(5) for details. Mirroring to a
+ GRE tunnel has fewer caveats than mirroring to a VLAN and should
+ generally be preferred.
+
+Q: How do I configure mirroring of all traffic to a GRE tunnel?
+
+A: The following commands configure br0 with eth0 and tap0 as trunk
+ ports. All traffic coming in or going out on eth0 or tap0 is also
+ mirrored to gre0, a GRE tunnel to the remote host 192.168.1.10; any
+ traffic arriving on gre0 is dropped:
+
+ ovs-vsctl add-br br0
+ ovs-vsctl add-port br0 eth0
+ ovs-vsctl add-port br0 tap0
+ ovs-vsctl add-port br0 gre0 \
+ -- set interface gre0 type=gre options:remote_ip=192.168.1.10 \
+ -- --id=@p get port gre0 \
+ -- --id=@m create mirror name=m0 select-all=true output-port=@p \
+ -- set bridge br0 mirrors=@m
+
+ To later disable mirroring and destroy the GRE tunnel:
+
+ ovs-vsctl clear bridge br0 mirrors
+ ovs-vcstl del-port br0 gre0
+
+Q: Does Open vSwitch support ERSPAN?
+
+A: No. ERSPAN is an undocumented proprietary protocol. As an
+ alternative, Open vSwitch supports mirroring to a GRE tunnel (see
+ above).
+
+
Configuration Problems
----------------------
VLANs
-----
+Q: What's a VLAN?
+
+A: At the simplest level, a VLAN (short for "virtual LAN") is a way to
+ partition a single switch into multiple switches. Suppose, for
+ example, that you have two groups of machines, group A and group B.
+ You want the machines in group A to be able to talk to each other,
+ and you want the machine in group B to be able to talk to each
+ other, but you don't want the machines in group A to be able to
+ talk to the machines in group B. You can do this with two
+ switches, by plugging the machines in group A into one switch and
+ the machines in group B into the other switch.
+
+ If you only have one switch, then you can use VLANs to do the same
+ thing, by configuring the ports for machines in group A as VLAN
+ "access ports" for one VLAN and the ports for group B as "access
+ ports" for a different VLAN. The switch will only forward packets
+ between ports that are assigned to the same VLAN, so this
+ effectively subdivides your single switch into two independent
+ switches, one for each group of machines.
+
+ So far we haven't said anything about VLAN headers. With access
+ ports, like we've described so far, no VLAN header is present in
+ the Ethernet frame. This means that the machines (or switches)
+ connected to access ports need not be aware that VLANs are
+ involved, just like in the case where we use two different physical
+ switches.
+
+ Now suppose that you have a whole bunch of switches in your
+ network, instead of just one, and that some machines in group A are
+ connected directly to both switches 1 and 2. To allow these
+ machines to talk to each other, you could add an access port for
+ group A's VLAN to switch 1 and another to switch 2, and then
+ connect an Ethernet cable between those ports. That works fine,
+ but it doesn't scale well as the number of switches and the number
+ of VLANs increases, because you use up a lot of valuable switch
+ ports just connecting together your VLANs.
+
+ This is where VLAN headers come in. Instead of using one cable and
+ two ports per VLAN to connect a pair of switches, we configure a
+ port on each switch as a VLAN "trunk port". Packets sent and
+ received on a trunk port carry a VLAN header that says what VLAN
+ the packet belongs to, so that only two ports total are required to
+ connect the switches, regardless of the number of VLANs in use.
+ Normally, only switches (either physical or virtual) are connected
+ to a trunk port, not individual hosts, because individual hosts
+ don't expect to see a VLAN header in the traffic that they receive.
+
+ None of the above discussion says anything about particular VLAN
+ numbers. This is because VLAN numbers are completely arbitrary.
+ One must only ensure that a given VLAN is numbered consistently
+ throughout a network and that different VLANs are given different
+ numbers. (That said, VLAN 0 is usually synonymous with a packet
+ that has no VLAN header, and VLAN 4095 is reserved.)
+
Q: VLANs don't work.
A: Many drivers in Linux kernels before version 3.3 had VLAN-related
normally an intermittent condition (unless ovs-vswitchd is not
running).
+Q: I added some flows with my controller or with ovs-ofctl, but when I
+ run "ovs-dpctl dump-flows" I don't see them.
+
+A: ovs-dpctl queries a kernel datapath, not an OpenFlow switch. It
+ won't display the information that you want. You want to use
+ "ovs-ofctl dump-flows" instead.
+
Contact
-------
git://git.onelab.eu / sliver-openvswitch.git / blobdiff