X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=FAQ;h=1a2c4f88e53e35a1cb45d2ea5bc6f175aca6edb8;hb=305b76debf72120672a8ba81d3356b6dccb1da9a;hp=a5c0cb9115c375e148691c0e45cca0b8b8afcdfc;hpb=a01b5c516d293765cfe564f5d340a6ccca9e0a29;p=sliver-openvswitch.git diff --git a/FAQ b/FAQ index a5c0cb911..1a2c4f88e 100644 --- a/FAQ +++ b/FAQ @@ -145,7 +145,7 @@ A: The following table lists the Linux kernel versions against which the 1.6.x 2.6.18 to 3.2 1.7.x 2.6.18 to 3.3 1.8.x 2.6.18 to 3.4 - 1.9.x 2.6.18 to 3.7 + 1.9.x 2.6.18 to 3.8 Open vSwitch userspace should also work with the Linux kernel module built into Linux 3.3 and later. @@ -154,32 +154,37 @@ A: The following table lists the Linux kernel versions against which the 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? A: The kernel module in upstream Linux 3.3 and later does not include - the following features: - - - Tunnel virtual ports, that is, interfaces with type "gre", - "ipsec_gre", "capwap". 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. - - Work is in progress in adding these features to the upstream - Linux version of the Open vSwitch kernel module. For now, if - you need these features, use the kernel module from the Open - vSwitch distribution instead of the upstream Linux kernel - module. - - - Patch virtual ports, that is, interfaces with type "patch". - You can use Linux "veth" devices as a substitute. - - We don't have any plans to add patch ports upstream. + tunnel virtual ports, that is, interfaces with type "gre", + "ipsec_gre", "gre64", "ipsec_gre64", "vxlan", or "capwap". 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. + + Work is in progress in adding tunnel virtual ports to the upstream + Linux version of the Open vSwitch kernel module. For now, if you + need these features, use the kernel module from the Open vSwitch + distribution instead of the upstream Linux kernel module. + + The upstream kernel module does not include patch ports, but this + only matters for Open vSwitch 1.9 and earlier, because Open vSwitch + 1.10 and later implement patch ports without using this kernel + feature. Q: What features are not available when using the userspace datapath? -A: Tunnel and patch virtual ports are not supported, as described in the +A: Tunnel virtual ports are not supported, as described in the previous answer. It is also not possible to use queue-related actions. On Linux kernels before 2.6.39, maximum-sized VLAN packets may not be transmitted. @@ -455,6 +460,110 @@ A: In version 1.9.0, OVS switched to using a single datapath that is commands provide similar functionality that is scoped by the bridge. +Quality of Service (QoS) +------------------------ + +Q: How do I configure Quality of Service (QoS)? + +A: Suppose that you want to set up bridge br0 connected to physical + Ethernet port eth0 (a 1 Gbps device) and virtual machine interfaces + vif1.0 and vif2.0, and that you want to limit traffic from vif1.0 + to eth0 to 10 Mbps and from vif2.0 to eth0 to 20 Mbps. Then, you + could configure the bridge this way: + + ovs-vsctl -- \ + add-br br0 -- \ + add-port br0 eth0 -- \ + add-port br0 vif1.0 -- set interface vif1.0 ofport_request=5 -- \ + add-port br0 vif2.0 -- set interface vif2.0 ofport_request=6 -- \ + set port eth0 qos=@newqos -- \ + --id=@newqos create qos type=linux-htb \ + other-config:max-rate=1000000000 \ + queues:123=@vif10queue \ + queues:234=@vif20queue -- \ + --id=@vif10queue create queue other-config:max-rate=10000000 -- \ + --id=@vif20queue create queue other-config:max-rate=20000000 + + At this point, bridge br0 is configured with the ports and eth0 is + configured with the queues that you need for QoS, but nothing is + actually directing packets from vif1.0 or vif2.0 to the queues that + we have set up for them. That means that all of the packets to + eth0 are going to the "default queue", which is not what we want. + + We use OpenFlow to direct packets from vif1.0 and vif2.0 to the + queues reserved for them: + + ovs-ofctl add-flow br0 in_port=5,actions=set_queue:123,normal + ovs-ofctl add-flow br0 in_port=6,actions=set_queue:234,normal + + Each of the above flows matches on the input port, sets up the + appropriate queue (123 for vif1.0, 234 for vif2.0), and then + executes the "normal" action, which performs the same switching + that Open vSwitch would have done without any OpenFlow flows being + present. (We know that vif1.0 and vif2.0 have OpenFlow port + numbers 5 and 6, respectively, because we set their ofport_request + columns above. If we had not done that, then we would have needed + to find out their port numbers before setting up these flows.) + + Now traffic going from vif1.0 or vif2.0 to eth0 should be + rate-limited. + + By the way, if you delete the bridge created by the above commands, + with: + + ovs-vsctl del-br br0 + + then that will leave one unreferenced QoS record and two + unreferenced Queue records in the Open vSwich database. One way to + clear them out, assuming you don't have other QoS or Queue records + that you want to keep, is: + + ovs-vsctl -- --all destroy QoS -- --all destroy Queue + +Q: I configured Quality of Service (QoS) in my OpenFlow network by + adding records to the QoS and Queue table, but the results aren't + what I expect. + +A: Did you install OpenFlow flows that use your queues? This is the + primary way to tell Open vSwitch which queues you want to use. If + you don't do this, then the default queue will be used, which will + probably not have the effect you want. + + Refer to the previous question for an example. + +Q: I configured QoS, correctly, but my measurements show that it isn't + working as well as I expect. + +A: With the Linux kernel, the Open vSwitch implementation of QoS has + two aspects: + + - Open vSwitch configures a subset of Linux kernel QoS + features, according to what is in OVSDB. It is possible that + this code has bugs. If you believe that this is so, then you + can configure the Linux traffic control (QoS) stack directly + with the "tc" program. If you get better results that way, + you can send a detailed bug report to bugs@openvswitch.org. + + It is certain that Open vSwitch cannot configure every Linux + kernel QoS feature. If you need some feature that OVS cannot + configure, then you can also use "tc" directly (or add that + feature to OVS). + + - The Open vSwitch implementation of OpenFlow allows flows to + be directed to particular queues. This is pretty simple and + unlikely to have serious bugs at this point. + + However, most problems with QoS on Linux are not bugs in Open + vSwitch at all. They tend to be either configuration errors + (please see the earlier questions in this section) or issues with + the traffic control (QoS) stack in Linux. The Open vSwitch + developers are not experts on Linux traffic control. We suggest + that, if you believe you are encountering a problem with Linux + traffic control, that you consult the tc manpages (e.g. tc(8), + tc-htb(8), tc-hfsc(8)), web resources (e.g. http://lartc.org/), or + mailing lists (e.g. http://vger.kernel.org/vger-lists.html#netdev). + + VLANs ----- @@ -661,12 +770,24 @@ Controllers Q: What versions of OpenFlow does Open vSwitch support? -A: Open vSwitch supports OpenFlow 1.0. It also includes a number of - extensions that bring many of the features from later versions of - OpenFlow. Work is underway to provide support for later versions and - can be tracked here: +A: Open vSwitch 1.9 and earlier support only OpenFlow 1.0 (plus + extensions that bring in many of the features from later versions + of OpenFlow). + + Open vSwitch versions 1.10 and later will have experimental support + for OpenFlow 1.2 and 1.3. On these versions of Open vSwitch, the + following command enables OpenFlow 1.0, 1.2, and 1.3 on bridge br0: + + ovs-vsctl set bridge br0 protocols=openflow10,openflow12,openflow13 + + Support for OpenFlow 1.1 is incomplete enough that it cannot yet be + enabled, even experimentally. - http://openvswitch.org/development/openflow-1-x-plan/ + Support for OpenFlow 1.2 and 1.3 is still incomplete. Work to be + done is tracked in OPENFLOW-1.1+ in the Open vSwitch source tree + (also via http://openvswitch.org/development/openflow-1-x-plan/). + When support for a given OpenFlow version is solidly implemented, + Open vSwitch will enable that version by default. Q: I'm getting "error type 45250 code 0". What's that?