doc: Remove some link targets that aren't used anywhere.

[mirror_ovs.git] / NEWS

Post-v2.7.0
---------------------
   - Tunnels:
     * Added support to set packet mark for tunnel endpoint using
       `egress_pkt_mark` OVSDB option.
   - EMC insertion probability is reduced to 1% and is configurable via
     the new 'other_config:emc-insert-inv-prob' option.
   - DPDK:
     * DPDK log messages redirected to OVS logging subsystem.
       Log level can be changed in a usual OVS way using
       'ovs-appctl vlog' commands for 'dpdk' module. Lower bound
       still can be configured via extra arguments for DPDK EAL.
   - New support for multiple VLANs (802.1ad or "QinQ"), including a new
     "dot1q-tunnel" port VLAN mode.
   - OVN:
     * Make the DHCPv4 router setting optional.
     * Gratuitous ARP for NAT addresses on a distributed logical router.
     * Allow ovn-controller SSL configuration to be obtained from vswitchd
       database.
   - Add the command 'ovs-appctl stp/show' (see ovs-vswitchd(8)).
   - OpenFlow:
     * Increased support for OpenFlow 1.6 (draft).
     * Bundles now support hashing by just nw_src or nw_dst.
     * The "learn" action now supports a "limit" option (see ovs-ofctl(8)).

v2.7.0 - 21 Feb 2017
---------------------
   - Utilities and daemons that support SSL now allow protocols and
     ciphers to be configured with --ssl-protocols and --ssl-ciphers.
   - OVN:
     * QoS is now implemented via egress shaping rather than ingress policing.
     * DSCP marking is now supported, via the new northbound QoS table.
     * IPAM now supports fixed MAC addresses.
     * Support for source IP address based routing.
     * ovn-trace:
       - New --ovs option to also print OpenFlow flows.
       - put_dhcp_opts and put_dhcp_optsv6 actions may now be traced.
     * Support for managing SSL and remote connection configuration in
       northbound and southbound databases.
     * TCP connections to northbound and southbound databases are no
       longer enabled by default and must be explicitly configured.
       See documentation for ovn-sbctl/ovn-nbctl "set-connection"
       command or the ovn-ctl "--db-sb-create-insecure-remote" and
       "--db-nb-create-insecure-remote" command-line options for
       information regarding remote connection configuration.
     * New appctl "inject-pkt" command in ovn-controller that allows
       packets to be injected into the connected OVS instance.
     * Distributed logical routers may now be connected directly to
       logical switches with localnet ports, by specifying a
       "redirect-chassis" on the distributed gateway port of the
       logical router.  NAT rules may be specified directly on the
       distributed logical router, and are handled either centrally on
       the "redirect-chassis", or in many cases are handled locally on
       the hypervisor where the corresponding logical port resides.
       Gratuitous ARP for NAT addresses on a distributed logical
       router is not yet supported, but will be added in a future
       version.
   - Fixed regression in table stats maintenance introduced in OVS
     2.3.0, wherein the number of OpenFlow table hits and misses was
     not accurate.
   - OpenFlow:
     * OFPT_PACKET_OUT messages are now supported in bundles.
     * A new "selection_method=dp_hash" type for OpenFlow select group
       bucket selection that uses the datapath computed 5-tuple hash
       without making datapath flows match the 5-tuple fields, which
       is useful for more efficient load balancing, for example.  This
       uses the Netronome extension to OpenFlow 1.5+ that allows
       control over the OpenFlow select groups selection method.  See
       "selection_method" and related options in ovs-ofctl(8) for
       details.
     * The "sample" action now supports "ingress" and "egress" options.
     * The "ct" action now supports the TFTP ALG where support is available.
     * New actions "clone" and "ct_clear".
   - ovs-ofctl:
     * 'bundle' command now supports packet-out messages.
     * New syntax for 'ovs-ofctl packet-out' command, which uses the
       same string parser as the 'bundle' command.  The old 'packet-out'
       syntax is deprecated and will be removed in a later OVS
       release.
     * New unixctl "ofctl/packet-out" command, which can be used to
       instruct a flow monitor to issue OpenFlow packet-out messages.
   - ovsdb-server:
     * Remote connections can now be made read-only (see ovsdb-server(1)).
   - Tunnels:
     * TLV mappings for protocols such as Geneve are now segregated on
       a per-OpenFlow bridge basis rather than globally. (The interface
       has not changed.)
     * Removed support for IPsec tunnels.
   - DPDK:
     * New option 'n_rxq_desc' and 'n_txq_desc' fields for DPDK interfaces
       which set the number of rx and tx descriptors to use for the given port.
     * Support for DPDK v16.11.
     * Support for rx checksum offload. Refer DPDK HOWTO for details.
     * Port Hotplug is now supported.
     * DPDK physical ports can now have arbitrary names. The PCI address of
       the device must be set using the 'dpdk-devargs' option. Compatibility
       with the old dpdk<portid> naming scheme is broken, and as such a
       device will not be available for use until a valid dpdk-devargs is
       specified.
     * Virtual DPDK Poll Mode Driver (vdev PMD) support.
     * Removed experimental tag.
   - Fedora packaging:
     * A package upgrade does not automatically restart OVS service.
   - ovs-vswitchd/ovs-vsctl:
     * Ports now have a "protected" flag. Protected ports can not forward
       frames to other protected ports. Unprotected ports can receive and
       forward frames to protected and other unprotected ports.
   - ovs-vsctl, ovn-nbctl, ovn-sbctl, vtep-ctl:
     * Database commands now accept integer ranges, e.g. "set port
       eth0 trunks=1-10" to enable trunking VLANs 1 to 10.

v2.6.0 - 27 Sep 2016
---------------------
   - First supported release of OVN.  See ovn-architecture(7) for more
     details.
   - ovsdb-server:
     * New "monitor_cond" "monitor_cond_update" and "update2" extensions to
       RFC 7047.
   - OpenFlow:
     * OpenFlow 1.3+ bundles now expire after 10 seconds since the
       last time the bundle was either opened, modified, or closed.
     * OpenFlow 1.3 Extension 230, adding OpenFlow Bundles support, is
       now implemented.
     * OpenFlow 1.3+ bundles are now supported for group mods as well as
       flow mods and port mods.  Both 'atomic' and 'ordered' bundle
       flags are supported for group mods as well as flow mods.
     * Internal OpenFlow rule representation for load and set-field
       actions is now much more memory efficient.  For a complex flow
       table this can reduce rule memory consumption by 40%.
     * Bundles are now much more memory efficient than in OVS 2.5.
       Together with memory efficiency improvements in OpenFlow rule
       representation, the peak OVS resident memory use during a
       bundle commit for large complex set of flow mods can be only
       25% of that in OVS 2.5 (4x lower).
     * OpenFlow 1.1+ OFPT_QUEUE_GET_CONFIG_REQUEST now supports OFPP_ANY.
     * OpenFlow 1.4+ OFPMP_QUEUE_DESC is now supported.
     * OpenFlow 1.4+ OFPT_TABLE_STATUS is now supported.
     * New property-based packet-in message format NXT_PACKET_IN2 with support
       for arbitrary user-provided data and for serializing flow table
       traversal into a continuation for later resumption.
     * New extension message NXT_SET_ASYNC_CONFIG2 to allow OpenFlow 1.4-like
       control over asynchronous messages in earlier versions of OpenFlow.
     * New OpenFlow extension NXM_NX_MPLS_TTL to provide access to MPLS TTL.
     * New output option, output(port=N,max_len=M), to allow truncating a
       packet to size M bytes when outputting to port N.
     * New command OFPGC_ADD_OR_MOD for OFPT_GROUP_MOD message that adds a
       new group or modifies an existing groups
     * The optional OpenFlow packet buffering feature is deprecated in
       this release, and will be removed in the next OVS release
       (2.7).  After the change OVS always sends the 'buffer_id' as
       0xffffffff in packet-in messages and will send an error
       response if any other value of this field is included in
       packet-out and flow mod sent by a controller.  Controllers are
       already expected to work properly in cases where the switch can
       not buffer packets, so this change should not affect existing
       users.
     * New OpenFlow extension NXT_CT_FLUSH_ZONE to flush conntrack zones.
   - Improved OpenFlow version compatibility for actions:
     * New OpenFlow extension to support the "group" action in OpenFlow 1.0.
     * OpenFlow 1.0 "enqueue" action now properly translated to OpenFlow 1.1+.
     * OpenFlow 1.1 "mod_nw_ecn" and OpenFlow 1.1+ "mod_nw_ttl" actions now
       properly translated to OpenFlow 1.0.
   - ovs-ofctl:
     * queue-get-config command now allows a queue ID to be specified.
     * '--bundle' option can now be used with OpenFlow 1.3 and with group mods.
     * New "bundle" command allows executing a mixture of flow and group mods
       as a single atomic transaction.
     * New option "--color" to produce colorized output for some commands.
     * New option '--may-create' to use OFPGC_ADD_OR_MOD in mod-group command.
   - IPFIX:
     * New "sampling_port" option for "sample" action to allow sampling
       ingress and egress tunnel metadata with IPFIX.
     * New ovs-ofctl commands "dump-ipfix-bridge" and "dump-ipfix-flow" to
       dump bridge IPFIX statistics and flow based IPFIX statistics.
     * New setting other-config:virtual_obs_id to add an arbitrary string
       to IPFIX records.
   - Linux:
     * OVS Linux datapath now implements Conntrack NAT action with all
       supported Linux kernels.
     * Support for truncate action.
     * New QoS type "linux-noop" that prevents Open vSwitch from trying to
       manage QoS for a given port (useful when other software manages QoS).
   - DPDK:
     * New option "n_rxq" for PMD interfaces.
       Old 'other_config:n-dpdk-rxqs' is no longer supported.
       Not supported by vHost interfaces. For them number of rx and tx queues
       is applied from connected virtio device.
     * New 'other_config:pmd-rxq-affinity' field for PMD interfaces, that
       allows to pin port's rx queues to desired cores.
     * New appctl command 'dpif-netdev/pmd-rxq-show' to check the port/rxq
       assignment.
     * Type of log messages from PMD threads changed from INFO to DBG.
     * QoS functionality with sample egress-policer implementation.
     * The mechanism for configuring DPDK has changed to use database
     * Sensible defaults have been introduced for many of the required
       configuration options
     * DB entries have been added for many of the DPDK EAL command line
       arguments. Additional arguments can be passed via the dpdk-extra
       entry.
     * Add ingress policing functionality.
     * PMD threads servicing vHost User ports can now come from the NUMA
       node that device memory is located on if CONFIG_RTE_LIBRTE_VHOST_NUMA
       is enabled in DPDK.
     * Basic connection tracking for the userspace datapath (no ALG,
       fragmentation or NAT support yet)
     * Support for DPDK 16.07
     * Optional support for DPDK pdump enabled.
     * Jumbo frame support
     * Remove dpdkvhostcuse port type.
     * OVS client mode for vHost and vHost reconnect (Requires QEMU 2.7)
     * 'dpdkvhostuserclient' port type.
   - Increase number of registers to 16.
   - ovs-benchmark: This utility has been removed due to lack of use and
     bitrot.
   - ovs-appctl:
     * New "vlog/close" command.
   - ovs-ctl:
     * Added the ability to selectively start the forwarding and database
       functions (ovs-vswitchd and ovsdb-server, respectively).
   - ovsdb-server:
     * Remove max number of sessions limit, to enable connection scaling
       testing.
   - python:
     * Added support for Python 3.4+ in addition to existing support
       for 2.7+.
   - SELinux:
     * Introduced SELinux policy package.
   - Datapath Linux kernel compatibility.
     * Dropped support for kernel older than 3.10.
     * Removed VLAN splinters feature.
     * Datapath supports kernel upto 4.7.
   - Tunnels:
     * Flow based tunnel match and action can be used for IPv6 address using
       tun_ipv6_src, tun_ipv6_dst fields.
     * Added support for IPv6 tunnels, for details checkout FAQ.
     * Deprecated support for IPsec tunnels ports.
   - A wrapper script, 'ovs-tcpdump', to easily port-mirror an OVS port and
     watch with tcpdump
   - Introduce --no-self-confinement flag that allows daemons to work with
     sockets outside their run directory.
   - ovs-pki: Changed message digest algorithm from SHA-1 to SHA-512 because
     SHA-1 is no longer secure and some operating systems have started to
     disable it in OpenSSL.
   - Add 'mtu_request' column to the Interface table. It can be used to
     configure the MTU of the ports.

Known issues:
   - Using openvswitch module in conjunction with upstream Linux tunnels:
     * When using the openvswitch module distributed with OVS against kernel
       versions 4.4 to 4.6, the openvswitch module cannot be loaded or used at
       the same time as "ip_gre".
   - Conntrack FTP ALGs: When using the openvswitch module distributed with
     OVS, particular Linux distribution kernels versions may provide diminished
     functionality. This typically affects active FTP data connections when
     using "actions=ct(alg=ftp),..." in flow tables. Specifically:
     * Centos 7.1 kernels (3.10.0-2xx) kernels are unable to correctly set
       up expectations for FTP data connections in multiple zones,
       eg "actions=ct(zone=1,alg=ftp),ct(zone=2,alg=ftp),...". Executing the
       "ct" action for subsequent data connections may fail to determine that
       the data connection is "related" to an existing connection.
     * Centos 7.2 kernels (3.10.0-3xx) kernels may not establish FTP ALG state
       correctly for NATed connections. As a result, flows that perform NAT,
       eg "actions=ct(nat,ftp=alg,table=1),..." may fail to NAT the packet,
       and will populate the "ct_state=inv" bit in the flow.


v2.5.0 - 26 Feb 2016
---------------------
   - Dropped support for Python older than version 2.7.  As a consequence,
     using Open vSwitch 2.5 or later on XenServer 6.5 or earlier (which
     have Python 2.4) requires first installing Python 2.7.
   - OpenFlow:
     * Group chaining (where one OpenFlow group triggers another) is
       now supported.
     * OpenFlow 1.4+ "importance" is now considered for flow eviction.
     * OpenFlow 1.4+ OFPTC_EVICTION is now implemented.
     * OpenFlow 1.4+ OFPTC_VACANCY_EVENTS is now implemented.
     * OpenFlow 1.4+ OFPMP_TABLE_DESC is now implemented.
     * Allow modifying the ICMPv4/ICMPv6 type and code fields.
     * OpenFlow 1.4+ OFPT_SET_ASYNC_CONFIG and OFPT_GET_ASYNC_CONFIG are
       now implemented.
   - ovs-ofctl:
     * New "out_group" keyword for OpenFlow 1.1+ matching on output group.
   - Tunnels:
     * Geneve tunnels can now match and set options and the OAM bit.
     * The nonstandard GRE64 tunnel extension has been dropped.
   - Support Multicast Listener Discovery (MLDv1 and MLDv2).
   - Add 'symmetric_l3l4' and 'symmetric_l3l4+udp' hash functions.
   - sFlow agent now reports tunnel and MPLS structures.
   - New 'check-system-userspace', 'check-kmod' and 'check-kernel' Makefile
     targets to run a new system testsuite.  These tests can be run inside
     a Vagrant box.  See INSTALL.md for details
   - Mark --syslog-target argument as deprecated.  It will be removed in
     the next OVS release.
   - Added --user option to all daemons
   - Add support for connection tracking through the new "ct" action
     and "ct_state"/"ct_zone"/"ct_mark"/"ct_label" match fields.  Only
     available on Linux kernels with the connection tracking module loaded.
   - Add experimental version of OVN.  OVN, the Open Virtual Network, is a
     system to support virtual network abstraction.  OVN complements the
     existing capabilities of OVS to add native support for virtual network
     abstractions, such as virtual L2 and L3 overlays and security groups.
   - RHEL packaging:
     * DPDK ports may now be created via network scripts (see README.RHEL).
   - DPDK:
     * Requires DPDK 2.2
     * Added multiqueue support to vhost-user
     * Note: QEMU 2.5+ required for multiqueue support

v2.4.0 - 20 Aug 2015
---------------------
   - Flow table modifications are now atomic, meaning that each packet
     now sees a coherent version of the OpenFlow pipeline.  For
     example, if a controller removes all flows with a single OpenFlow
     "flow_mod", no packet sees an intermediate version of the OpenFlow
     pipeline where only some of the flows have been deleted.
   - Added support for SFQ, FQ_CoDel and CoDel qdiscs.
   - Add bash command-line completion support for ovs-vsctl Please check
     utilities/ovs-command-compgen.INSTALL.md for how to use.
   - The MAC learning feature now includes per-port fairness to mitigate
     MAC flooding attacks.
   - New support for a "conjunctive match" OpenFlow extension, which
     allows constructing OpenFlow matches of the form "field1 in
     {a,b,c...} AND field2 in {d,e,f...}" and generalizations.  For details,
     see documentation for the "conjunction" action in ovs-ofctl(8).
   - Add bash command-line completion support for ovs-appctl/ovs-dpctl/
     ovs-ofctl/ovsdb-tool commands.  Please check
     utilities/ovs-command-compgen.INSTALL.md for how to use.
   - The "learn" action supports a new flag "delete_learned" that causes
     the learned flows to be deleted when the flow with the "learn" action
     is deleted.
   - Basic support for the Geneve tunneling protocol. It is not yet
     possible to generate or match options. This is planned for a future
     release. The protocol is documented at
     http://tools.ietf.org/html/draft-gross-geneve-00
   - The OVS database now reports controller rate limiting statistics.
   - sflow now exports information about LACP-based bonds, port names, and
     OpenFlow port numbers, as well as datapath performance counters.
   - ovs-dpctl functionality is now available for datapaths integrated
     into ovs-vswitchd, via ovs-appctl.  Some existing ovs-appctl
     commands are now redundant and will be removed in a future
     release.  See ovs-vswitchd(8) for details.
   - OpenFlow:
     * OpenFlow 1.4 bundles are now supported for flow mods and port
       mods.  For flow mods, both 'atomic' and 'ordered' bundle flags
       are trivially supported, as all bundled messages are executed
       in the order they were added and all flow table modifications
       are now atomic to the datapath.  Port mods may not appear in
       atomic bundles, as port status modifications are not atomic.
     * IPv6 flow label and neighbor discovery fields are now modifiable.
     * OpenFlow 1.5 extended registers are now supported.
     * The OpenFlow 1.5 actset_output field is now supported.
     * OpenFlow 1.5 Copy-Field action is now supported.
     * OpenFlow 1.5 masked Set-Field action is now supported.
     * OpenFlow 1.3+ table features requests are now supported (read-only).
     * Nicira extension "move" actions may now be included in action sets.
     * "resubmit" actions may now be included in action sets.  The resubmit
       is executed last, and only if the action set has no "output" or "group"
       action.
     * OpenFlow 1.4+ flow "importance" is now maintained in the flow table.
     * A new Netronome extension to OpenFlow 1.5+ allows control over the
       fields hashed for OpenFlow select groups.  See "selection_method" and
       related options in ovs-ofctl(8) for details.
   - ovs-ofctl has a new '--bundle' option that makes the flow mod commands
     ('add-flow', 'add-flows', 'mod-flows', 'del-flows', and 'replace-flows')
     use an OpenFlow 1.4 bundle to operate the modifications as a single
     atomic transaction.  If any of the flow mods in a transaction fail, none
     of them are executed.  All flow mods in a bundle appear to datapath
     lookups simultaneously.
   - ovs-ofctl 'add-flow' and 'add-flows' commands now accept arbitrary flow
     mods as an input by allowing the flow specification to start with an
     explicit 'add', 'modify', 'modify_strict', 'delete', or 'delete_strict'
     keyword.  A missing keyword is treated as 'add', so this is fully
     backwards compatible.  With the new '--bundle' option all the flow mods
     are executed as a single atomic transaction using an OpenFlow 1.4 bundle.
   - ovs-pki: Changed message digest algorithm from MD5 to SHA-1 because
     MD5 is no longer secure and some operating systems have started to disable
     it in OpenSSL.
   - ovsdb-server: New OVSDB protocol extension allows inequality tests on
     "optional scalar" columns.  See ovsdb-server(1) for details.
   - ovs-vsctl now permits immutable columns in a new row to be modified in
     the same transaction that creates the row.
   - test-controller has been renamed ovs-testcontroller at request of users
     who find it useful for testing basic OpenFlow setups.  It is still not
     a necessary or desirable part of most Open vSwitch deployments.
   - Support for travis-ci.org based continuous integration builds has been
     added. Build failures are reported to build@openvswitch.org. See INSTALL.md
     file for additional details.
   - Support for the Rapid Spanning Tree Protocol (IEEE 802.1D-2004).
     The implementation has been tested successfully against the Ixia Automated
     Network Validation Library (ANVL).
   - Stats are no longer updated on fake bond interface.
   - Keep active bond slave selection across OVS restart.
   - A simple wrapper script, 'ovs-docker', to integrate OVS with Docker
     containers. If and when there is a native integration of Open vSwitch
     with Docker, the wrapper script will be retired.
   - Added support for DPDK Tunneling. VXLAN, GRE, and Geneve are supported
     protocols. This is generic tunneling mechanism for userspace datapath.
   - Support for multicast snooping (IGMPv1, IGMPv2 and IGMPv3)
   - Support for Linux kernels up to 4.0.x
   - The documentation now use the term 'destination' to mean one of syslog,
     console or file for vlog logging instead of the previously used term
     'facility'.
   - Support for VXLAN Group Policy extension
   - Initial support for the IETF Auto-Attach SPBM draft standard. This
     contains rudimentary support for the LLDP protocol as needed for
     Auto-Attach.
   - The default OpenFlow and OVSDB ports are now the IANA-assigned
     numbers.  OpenFlow is 6653 and OVSDB is 6640.
   - Support for DPDK vHost.
   - Support for outer UDP checksums in Geneve and VXLAN.
   - The kernel vports with dependencies are no longer part of the overall
     openvswitch.ko but built and loaded automatically as individual kernel
     modules (vport-*.ko).
   - Support for STT tunneling.
   - ovs-sim: New developer tool for simulating multiple OVS instances.
     See ovs-sim(1) for more information.
   - Support to configure method (--syslog-method argument) that determines
     how daemons will talk with syslog.
   - Support for "ovs-appctl vlog/list-pattern" command that lets to query
     logging message format for each destination.


v2.3.0 - 14 Aug 2014
---------------------
   - OpenFlow 1.1, 1.2, and 1.3 are now enabled by default in
     ovs-vswitchd.
   - Linux kernel datapath now has an exact match cache optimizing the
     flow matching process.
   - Datapath flows now have partially wildcarded tranport port field
     matches.  This reduces userspace upcalls, but increases the
     number of different masks in the datapath.  The kernel datapath
     exact match cache removes the overhead of matching the incoming
     packets with the larger number of masks, but when paired with an
     older kernel module, some workloads may perform worse with the
     new userspace.
   - Compatibility with autoconf 2.63 (previously >=2.64)

v2.2.0 - Internal Release
---------------------
   - Internal ports are no longer brought up by default, because it
     should be an administrator task to bring up devices as they are
     configured properly.
   - ovs-vsctl now reports when ovs-vswitchd fails to create a new port or
     bridge.
   - Port creation and configuration errors are now stored in a new error
     column of the Interface table and included in 'ovs-vsctl show'.
   - The "ovsdbmonitor" graphical tool has been removed, because it was
     poorly maintained and not widely used.
   - New "check-ryu" Makefile target for running Ryu tests for OpenFlow
     controllers against Open vSwitch.  See INSTALL.md for details.
   - Added IPFIX support for SCTP flows and templates for ICMPv4/v6 flows.
   - Upon the receipt of a SIGHUP signal, ovs-vswitchd no longer reopens its
     log file (it will terminate instead). Please use 'ovs-appctl vlog/reopen'
     instead.
   - Support for Linux kernels up to 3.14. From Kernel 3.12 onwards OVS uses
     tunnel API for GRE and VXLAN.
   - Added DPDK support.
   - Added support for custom vlog patterns in Python


v2.1.0 - 19 Mar 2014
---------------------
   - Address prefix tracking support for flow tables.  New columns
     "prefixes" in OVS-DB table "Flow_Table" controls which packet
     header fields are used for address prefix tracking.  Prefix
     tracking allows the classifier to skip rules with longer than
     necessary prefixes, resulting in better wildcarding for datapath
     flows.  Default configuration is to not use any fields for prefix
     tracking.  However, if any flow tables contain both exact matches
     and masked matches for IP address fields, OVS performance may be
     increased by using this feature.
     * As of now, the fields for which prefix lookup can be enabled
       are: 'tun_id', 'tun_src', 'tun_dst', 'nw_src', 'nw_dst' (or
       aliases 'ip_src' and 'ip_dst'), 'ipv6_src', and 'ipv6_dst'.
       (Using this feature for 'tun_id' would only make sense if the
       tunnel IDs have prefix structure similar to IP addresses.)
     * There is a maximum number of fields that can be enabled for any
       one flow table.  Currently this limit is 3.
     * Examples:
       $ ovs-vsctl set Bridge br0 flow_tables:0=@N1 -- \
         --id=@N1 create Flow_Table name=table0
       $ ovs-vsctl set Bridge br0 flow_tables:1=@N1 -- \
         --id=@N1 create Flow_Table name=table1
       $ ovs-vsctl set Flow_Table table0 prefixes=ip_dst,ip_src
       $ ovs-vsctl set Flow_Table table1 prefixes=[]
   - TCP flags matching: OVS now supports matching of TCP flags.  This
     has an adverse performance impact when using OVS userspace 1.10
     or older (no megaflows support) together with the new OVS kernel
     module.  It is recommended that the kernel and userspace modules
     both are upgraded at the same time.
   - The default OpenFlow and OVSDB ports will change to
     IANA-assigned numbers in a future release.  Consider updating
     your installations to specify port numbers instead of using the
     defaults.
   - OpenFlow:
     * The OpenFlow 1.1+ "Write-Actions" instruction is now supported.
     * OVS limits the OpenFlow port numbers it assigns to port 32767 and
       below, leaving port numbers above that range free for assignment
       by the controller.
     * ovs-vswitchd now honors changes to the "ofport_request" column
       in the Interface table by changing the port's OpenFlow port
       number.
     * The Open vSwitch software switch now supports OpenFlow groups.
   - ovs-vswitchd.conf.db.5 man page will contain graphviz/dot
     diagram only if graphviz package was installed at the build time.
   - Support for Linux kernels up to 3.11
   - ovs-dpctl:
     The "show" command also displays mega flow mask stats.
   - ovs-ofctl:
     * New command "ofp-parse-pcap" to dump OpenFlow from PCAP files.
   - ovs-controller has been renamed test-controller.  It is no longer
     packaged or installed by default, because too many users assumed
     incorrectly that ovs-controller was a necessary or desirable part
     of an Open vSwitch deployment.
   - Added vlog option to export to a UDP syslog sink.
   - ovsdb-client:
     * The "monitor" command can now monitor all tables in a database,
       instead of being limited to a single table.
   - The flow-eviction-threshold has been replaced by the flow-limit which is a
     hard limit on the number of flows in the datapath.  It defaults to 200,000
     flows.  OVS automatically adjusts this number depending on network
     conditions.
   - Added IPv6 support for active and passive socket communications.


v2.0.0 - 15 Oct 2013
---------------------
    - The ovs-vswitchd process is no longer single-threaded.  Multiple
      threads are now used to handle flow set up and asynchronous
      logging.
    - OpenFlow:
      * Experimental support for OpenFlow 1.1 (in addition to 1.2 and
        1.3, which had experimental support in 1.10).
      * Experimental protocol support for OpenFlow 1.1+ groups.  This
        does not yet include an implementation in the Open vSwitch
        software switch.
      * Experimental protocol support for OpenFlow 1.2+ meters.  This
        does not yet include an implementation in the Open vSwitch
        software switch.
      * New support for matching outer source and destination IP address
        of tunneled packets, for tunnel ports configured with the newly
        added "remote_ip=flow" and "local_ip=flow" options.
      * Support for matching on metadata 'pkt_mark' for interacting with
        other system components. On Linux this corresponds to the skb
        mark.
      * Support matching, rewriting SCTP ports
    - The Interface table in the database has a new "ifindex" column to
      report the interface's OS-assigned ifindex.
    - New "check-oftest" Makefile target for running OFTest against Open
      vSwitch.  See README-OFTest for details.
    - The flow eviction threshold has been moved to the Open_vSwitch table.
    - Database names are now mandatory when specifying ovsdb-server options
      through database paths (e.g. Private key option with the database name
      should look like "--private-key=db:Open_vSwitch,SSL,private_key").
    - Added ovs-dev.py, a utility script helpful for Open vSwitch developers.
    - Support for Linux kernels up to 3.10
    - ovs-ofctl:
      * New "ofp-parse" for printing OpenFlow messages read from a file.
      * New commands for OpenFlow 1.1+ groups.
    - Added configurable flow caching support to IPFIX exporter.
    - Dropped support for Linux pre-2.6.32.
    - Log file timestamps and ovsdb commit timestamps are now reported
      with millisecond resolution.  (Previous versions only reported
      whole seconds.)


v1.11.0 - 28 Aug 2013
---------------------
    - Support for megaflows, which allows wildcarding in the kernel (and
      any dpif implementation that supports wildcards).  Depending on
      the flow table and switch configuration, flow set up rates are
      close to the Linux bridge.
    - The "tutorial" directory contains a new tutorial for some advanced
      Open vSwitch features.
    - Stable bond mode has been removed.
    - The autopath action has been removed.
    - New support for the data encapsulation format of the LISP tunnel
      protocol (RFC 6830).  An external control plane or manual flow
      setup is required for EID-to-RLOC mapping.
    - OpenFlow:
      * The "dec_mpls_ttl" and "set_mpls_ttl" actions from OpenFlow
        1.1 and later are now implemented.
      * New "stack" extension for use in actions, to push and pop from
        NXM fields.
      * The "load" and "set_field" actions can now modify the "in_port".  (This
        allows one to enable output to a flow's input port by setting the
        in_port to some unused value, such as OFPP_NONE.)
    - ovs-dpctl:
      * New debugging commands "add-flow", "mod-flow", "del-flow".
      * "dump-flows" now has a -m option to increase output verbosity.
    - In dpif-based bridges, cache action translations, which can improve
      flow set up performance by 80% with a complicated flow table.
    - New syslog format, prefixed with "ovs|", to be easier to filter.
    - RHEL: Removes the default firewall rule that allowed GRE traffic to
      pass through. Any users that relied on this automatic firewall hole
      will have to manually configure it. The ovs-ctl(8) manpage documents
      the "enable-protocol" command that can be used as an alternative.
    - New CFM demand mode which uses data traffic to indicate interface
      liveness.

v1.10.0 - 01 May 2013
---------------------
    - Bridge compatibility support has been removed.  Any uses that
      rely on ovs-brcompatd will have to stick with Open vSwitch 1.9.x
      or adapt to native Open vSwitch support (e.g. use ovs-vsctl instead
      of brctl).
    - The maximum size of the MAC learning table is now configurable.
    - With the Linux datapath, packets for new flows are now queued
      separately on a per-port basis, so it should no longer be
      possible for a large number of new flows arriving on one port to
      prevent new flows from being processed on other ports.
    - ovs-vsctl:
      * Previously ovs-vsctl would retry connecting to the database forever,
        causing it to hang if ovsdb-server was not running.  Now, ovs-vsctl
        only tries once by default (use --retry to try forever).  This change
        means that you may want to remove uses of --timeout to avoid hangs
        in ovs-vsctl calls.
      * Many "ovs-vsctl" database commands now accept an --if-exists option.
        Please refer to the ovs-vsctl manpage for details.
    - OpenFlow:
      - Experimental support for newer versions of OpenFlow.  See
        the "What versions of OpenFlow does Open vSwitch support?"
        question in the FAQ for more details.
      - The OpenFlow "dp_desc" may now be configured by setting the
        value of other-config:dp-desc in the Bridge table.
      - It is possible to request the OpenFlow port number with the
        "ofport_request" column in the Interface table.
      - The NXM flow_removed message now reports the OpenFlow table ID
        from which the flow was removed.
    - Tunneling:
      - New support for the VXLAN tunnel protocol (see the IETF draft here:
        http://tools.ietf.org/html/draft-mahalingam-dutt-dcops-vxlan-03).
      - Tunneling requires the version of the kernel module paired with
        Open vSwitch 1.9.0 or later.
      - Inheritance of the Don't Fragment bit in IP tunnels (df_inherit)
        is no longer supported.
      - Path MTU discovery is no longer supported.
      - CAPWAP tunneling support removed.
      - Tunnels with multicast destination ports are no longer supported.
    - ovs-dpctl:
      - The "dump-flows" and "del-flows" no longer require an argument
        if only one datapath exists.
    - ovs-appctl:
      - New "vlog/disable-rate-limit" and "vlog/enable-rate-limit"
        commands available allow control over logging rate limits.
      - New "dpif/dump-dps", "dpif/show", and "dpif/dump-flows" command
        that mimic the equivalent ovs-dpctl commands.
    - The ofproto library is now responsible for assigning OpenFlow port
      numbers.  An ofproto implementation should assign them when
      port_construct() is called.
    - All dpif-based bridges of a particular type share a common
      datapath called "ovs-<type>", e.g. "ovs-system".  The ovs-dpctl
      commands will now return information on that shared datapath.  To
      get the equivalent bridge-specific information, use the new
      "ovs-appctl dpif/*" commands.
    - Backward-incompatible changes:
      - Earlier Open vSwitch versions treated ANY as a wildcard in flow
        syntax.  OpenFlow 1.1 adds a port named ANY, which introduces a
        conflict.  ANY was rarely used in flow syntax, so we chose to
        retire that meaning of ANY in favor of the OpenFlow 1.1 meaning.
    - Patch ports no longer require kernel support, so they now work
      with FreeBSD and the kernel module built into Linux 3.3 and later.
    - New "sample" action.


v1.9.0 - 26 Feb 2013
------------------------
    - Datapath:
      - Support for ipv6 set action.
      - SKB mark matching and setting.
      - support for Linux kernels up to 3.8
    - FreeBSD is now a supported platform, thanks to code contributions from
      Gaetano Catalli, Ed Maste, and Giuseppe Lettieri.
    - ovs-bugtool: New --ovs option to report only OVS related information.
    - New %t and %T log escapes to identify the subprogram within a
      cooperating group of processes or threads that emitted a log message.
      The default log patterns now include this information.
    - OpenFlow:
      - Allow bitwise masking for SHA and THA fields in ARP, SLL and TLL
        fields in IPv6 neighbor discovery messages, and IPv6 flow label.
      - Adds support for writing to the metadata field for a flow.
    - Tunneling:
      - The tunneling code no longer assumes input and output keys are
        symmetric.  If they are not, PMTUD needs to be disabled for
        tunneling to work. Note this only applies to flow-based keys.
      - New support for a nonstandard form of GRE that supports a 64-bit key.
      - Tunnel Path MTU Discovery default value was set to 'disabled'.
        This feature is deprecated and will be removed soon.
      - Tunnel header caching removed.
    - ovs-ofctl:
      - Commands and actions that accept port numbers now also accept keywords
        that represent those ports (such as LOCAL, NONE, and ALL).  This is
        also the recommended way to specify these ports, for compatibility
        with OpenFlow 1.1 and later (which use the OpenFlow 1.0 numbers
        for these ports for different purposes).
    - ovs-dpctl:
      - Support requesting the port number with the "port_no" option in
        the "add-if" command.
    - ovs-pki: The "online PKI" features have been removed, along with
      the ovs-pki-cgi program that facilitated it, because of some
      alarmist insecurity claims.  We do not believe that these claims
      are true, but because we do not know of any users for this
      feature it seems better on balance to remove it.  (The ovs-pki-cgi
      program was not included in distribution packaging.)
    - ovsdb-server now enforces the immutability of immutable columns.  This
      was not enforced in earlier versions due to an oversight.
    - The following features are now deprecated.  They will be removed no
      earlier than February 2013.  Please email dev@openvswitch.org with
      concerns.
        - Bridge compatibility.
        - Stable bond mode.
        - The autopath action.
        - Interface type "null".
        - Numeric values for reserved ports (see "ovs-ofctl" note above).
        - Tunnel Path MTU Discovery.
        - CAPWAP tunnel support.
    - The data in the RARP packets can now be matched in the same way as the
      data in ARP packets.


v1.8.0 - 26 Feb 2013
------------------------
    *** Internal only release ***
    - New FAQ.  Please send updates and additions!
    - Authors of controllers, please read the new section titled "Action
      Reproduction" in DESIGN, which describes an Open vSwitch change in
      behavior in corner cases that may affect some controllers.
    - ovs-l3ping:
        - A new test utility that can create L3 tunnel between two Open
          vSwitches and detect connectivity issues.
    - ovs-ofctl:
        - New --sort and --rsort options for "dump-flows" command.
        - "mod-port" command can now control all OpenFlow config flags.
    - OpenFlow:
      - Allow general bitwise masking for IPv4 and IPv6 addresses in
        IPv4, IPv6, and ARP packets.  (Previously, only CIDR masks
        were allowed.)
      - Allow support for arbitrary Ethernet masks.  (Previously, only
        the multicast bit in the destination address could be individually
	masked.)
      - New field OXM_OF_METADATA, to align with OpenFlow 1.1.
      - The OFPST_QUEUE request now reports an error if a specified port or
        queue does not exist, or for requests for a specific queue on all
        ports, if the specified queue does not exist on any port.  (Previous
        versions generally reported an empty set of results.)
      - New "flow monitor" feature to allow controllers to be notified of
        flow table changes as they happen.
    - Additional protocols are not mirrored and dropped when forward-bpdu is
      false.  For a full list, see the ovs-vswitchd.conf.db man page.
    - Open vSwitch now sends RARP packets in situations where it previously
      sent a custom protocol, making it consistent with behavior of QEMU and
      VMware.
    - All Open vSwitch programs and log files now show timestamps in UTC,
      instead the local timezone, by default.


v1.7.0 - 30 Jul 2012
------------------------
    - kernel modules are renamed. openvswitch_mod.ko is now
      openvswitch.ko and brcompat_mod.ko is now brcompat.ko.
    - Increased the number of NXM registers to 8.
    - Added ability to configure DSCP setting for manager and controller
      connections.  By default, these connections have a DSCP value of
      Internetwork Control (0xc0).
    - Added the granular link health statistics, 'cfm_health', to an
      interface.
    - OpenFlow:
        - Added support to mask nd_target for ICMPv6 neighbor discovery flows.
        - Added support for OpenFlow 1.3 port description (OFPMP_PORT_DESC)
          multipart messages.
    - ovs-ofctl:
        - Added the "dump-ports-desc" command to retrieve port
          information using the new port description multipart messages.
    - ovs-test:
        - Added support for spawning ovs-test server from the client.
        - Now ovs-test is able to automatically create test bridges and ports.
    - "ovs-dpctl dump-flows" now prints observed TCP flags in TCP flows.
    - Tripled flow setup performance.
    - The "coverage/log" command previously available through ovs-appctl
      has been replaced by "coverage/show".  The new command replies with
      coverage counter values, instead of logging them.


v1.6.1 - 25 Jun 2012
------------------------
    - Allow OFPP_CONTROLLER as the in_port for packet-out messages.


v1.6.0 - 24 Feb 2012
------------------------
    *** Internal only release ***
    - bonding
        - LACP bonds no longer fall back to balance-slb when negotiations fail.
          Instead they drop traffic.
        - The default bond_mode changed from SLB to active-backup, to protect
          unsuspecting users from the significant risks of SLB bonds (which are
          documented in vswitchd/INTERNALS).
        - Load balancing can be disabled by setting the bond-rebalance-interval
          to zero.
    - OpenFlow:
        - Added support for bitwise matching on TCP and UDP ports.
          See ovs-ofctl(8) for more information.
        - NXM flow dumps now include times elapsed toward idle and hard
          timeouts.
        - Added an OpenFlow extension NXT_SET_ASYNC_CONFIG that allows
          controllers more precise control over which OpenFlow messages they
          receive asynchronously.
        - New "fin_timeout" action.
        - Added "fin_timeout" support to "learn" action.
        - New Nicira action NXAST_CONTROLLER that offers additional features
          over output to OFPP_CONTROLLER.
    - When QoS settings for an interface do not configure a default queue
      (queue 0), Open vSwitch now uses a default configuration for that
      queue, instead of dropping all packets as in previous versions.
    - Logging:
        - Logging to console and file will have UTC timestamp as a default for
          all the daemons. An example of the default format is
          2012-01-27T16:35:17Z.  ovs-appctl can be used to change the default
          format as before.
        - The syntax of commands and options to set log levels was simplified,
          to make it easier to remember.
    - New support for limiting the number of flows in an OpenFlow flow
      table, with configurable policy for evicting flows upon
      overflow.  See the Flow_Table table in ovs-vswitch.conf.db(5)
      for more information.
    - New "enable-async-messages" column in the Controller table.  If set to
      false, OpenFlow connections to the controller will initially have all
      asynchronous messages disabled, overriding normal OpenFlow behavior.
    - ofproto-provider interface:
        - "struct rule" has a new member "used" that ofproto implementations
          should maintain by updating with ofproto_rule_update_used().
    - ovsdb-client:
        - The new option --timestamp causes the "monitor" command to print
          a timestamp with every update.
    - CFM module CCM broadcasts can now be tagged with an 802.1p priority.


v1.5.0 - 01 Jun 2012
------------------------
    - OpenFlow:
        - Added support for querying, modifying, and deleting flows
          based on flow cookie when using NXM.
        - Added new NXM_PACKET_IN format.
        - Added new NXAST_DEC_TTL action.
    - ovs-ofctl:
        - Added daemonization support to the monitor and snoop commands.
    - ovs-vsctl:
        - The "find" command supports new set relational operators
          {=}, {!=}, {<}, {>}, {<=}, and {>=}.
    - ovsdb-tool now uses the typical database and schema installation
      directories as defaults.
    - The default MAC learning timeout has been increased from 60 seconds
      to 300 seconds.  The MAC learning timeout is now configurable.


v1.4.0 - 30 Jan 2012
------------------------
    - Compatible with Open vSwitch kernel module included in Linux 3.3.
    - New "VLAN splinters" feature to work around buggy device drivers
      in old Linux versions.  (This feature is deprecated.  When
      broken device drivers are no longer in widespread use, we will
      delete this feature.)  See ovs-vswitchd.conf.db(5) for more
      information.
    - OpenFlow:
       - Added ability to match on IPv6 flow label through NXM.
       - Added ability to match on ECN bits in IPv4 and IPv6 through NXM.
       - Added ability to match on TTL in IPv4 and IPv6 through NXM.
       - Added ability to modify ECN bits in IPv4.
       - Added ability to modify TTL in IPv4.
    - ovs-vswitchd:
       - Don't require the "normal" action to use mirrors.  Traffic will
         now be properly mirrored for any flows, regardless of their
         actions.
       - Track packet and byte statistics sent on mirrors.
       - The sFlow implementation can now usually infer the correct agent
         device instead of having to be told explicitly.
    - ovs-appctl:
      - New "fdb/flush" command to flush bridge's MAC learning table.
    - ovs-test:
      - A new distributed testing tool that allows one to diagnose performance
        and connectivity issues. This tool currently is not included in RH or
        Xen packages.
    - RHEL packaging now supports integration with Red Hat network scripts.
    - bonding:
      - Post 1.4.*, OVS will be changing the default bond mode from balance-slb
        to active-backup.  SLB bonds carry significant risks with them
        (documented vswitchd/INTERNALS) which we want to prevent unsuspecting
        users from running into.  Users are advised to update any scripts or
        configuration which may be negatively impacted by explicitly setting
        the bond mode which they want to use.


v1.3.0 - 09 Dec 2011
------------------------
    - OpenFlow:
      - Added an OpenFlow extension which allows the "output" action to accept
        NXM fields.
      - Added an OpenFlow extension for flexible learning.
      - Bumped number of NXM registers from four to five.
    - ovs-appctl:
      - New "version" command to determine version of running daemon.
      - If no argument is provided for "cfm/show", displays detailed
        information about all interfaces with CFM enabled.
      - If no argument is provided for "lacp/show", displays detailed
        information about all ports with LACP enabled.
    - ovs-dpctl:
      - New "set-if" command to modify a datapath port's configuration.
    - ovs-vswitchd:
      - The software switch now supports 255 OpenFlow tables, instead
        of just one.  By default, only table 0 is consulted, but the
        new NXAST_RESUBMIT_TABLE action can look up in additional
        tables.  Tables 128 and above are reserved for use by the
        switch itself; please use only tables 0 through 127.
      - Add support for 802.1D spanning tree (STP).
    - Fragment handling extensions:
      - New OFPC_FRAG_NX_MATCH fragment handling mode, in which L4
        fields are made available for matching in fragments with
        offset 0.
      - New NXM_NX_IP_FRAG match field for matching IP fragments (usable
        via "ip_frag" in ovs-ofctl).
      - New ovs-ofctl "get-frags" and "set-frags" commands to get and set
        fragment handling policy.
    - CAPWAP tunneling now supports an extension to transport a 64-bit key.
      By default it remains compatible with the old version and other
      standards-based implementations.
    - Flow setups are now processed in a round-robin manner across ports
      to prevent any single client from monopolizing the CPU and conducting
      a denial of service attack.
    - Added support for native VLAN tagging.  A new "vlan_mode"
      parameter can be set for "port". Possible values: "access",
      "trunk", "native-tagged" and "native-untagged".
    - test-openflowd has been removed.  Please use ovs-vswitchd instead.

v1.2.0 - 03 Aug 2011
------------------------
    - New "ofproto" abstraction layer to ease porting to hardware
      switching ASICs.
    - Packaging for Red Hat Enterprise Linux 5.6 and 6.0.
    - Datapath support for Linux kernels up to 3.0.
    - OpenFlow:
      - New "bundle" and "bundle_load" action extensions.
    - Database:
      - Implement table unique constraints.
      - Support cooperative locking between callers.
    - ovs-dpctl:
      - New "-s" option for "show" command prints packet and byte
        counters for each port.
    - ovs-ofctl:
      - New "--readd" option for "replace-flows".
    - ovs-vsctl:
      - New "show" command to print an overview of configuration.
      - New "comment" command to add remark that explains intentions.
    - ovs-brcompatd has been rewritten to fix long-standing bugs.
    - ovs-openflowd has been renamed test-openflowd and moved into the
      tests directory.  Its presence confused too many users.  Please
      use ovs-vswitchd instead.
    - New ovs-benchmark utility to test flow setup performance.
    - A new log level "off" has been added.  Configuring a log facility
      "off" prevents any messages from being logged to it.  Previously,
      "emer" was effectively "off" because no messages were ever logged at
      level "emer".  Now, errors that cause a process to exit are logged
      at "emer" level.
    - "configure" option --with-l26 has been renamed --with-linux, and
      --with-l26-source has been renamed --with-linux-source.  The old
      names will be removed after the next release, so please update
      your scripts.
    - The "-2.6" suffix has been dropped from the datapath/linux-2.6 and
      datapath/linux-2.6/compat-2.6 directories.
    - Feature removals:
      - Dropped support for "tun_id_from_cookie" OpenFlow extension.
           Please use the extensible match extensions instead.
      - Removed the Maintenance_Point and Monitor tables in an effort
        to simplify 802.1ag configuration.
    - Performance and scalability improvements
    - Bug fixes

v1.1.0 - 05 Apr 2011
------------------------
    - Ability to define policies over IPv6
    - LACP
    - 802.1ag CCM
    - Support for extensible match extensions to OpenFlow
    - QoS:
      - Support for HFSC qdisc.
      - Queue used by in-band control can now be configured.
    - Kernel:
      - Kernel<->userspace interface has been reworked and should be
        close to a stable ABI now.
      - "Port group" concept has been dropped.
    - GRE over IPSEC tunnels
    - Bonding:
      - New active backup bonding mode.
      - New L4 hashing support when LACP is enabled.
      - Source MAC hash now includes VLAN field also.
      - miimon support.
    - Greatly improved handling of large flow tables
    - ovs-dpctl:
      - "show" command now prints full vport configuration.
      - "dump-groups" command removed since kernel support for
        port groups was dropped.
    - ovs-vsctl:
      - New commands for working with the new Managers table.
      - "list" command enhanced with new formatting options and --columns
        option.
      - "get" command now accepts new --id option.
      - New "find" command.
    - ovs-ofctl:
      - New "queue-stats" command for printing queue stats.
      - New commands "replace-flows" and "diff-flows".
      - Commands to add and remove flows can now read from files.
      - New --flow-format option to enable or disable NXM.
      - New --more option to increase OpenFlow message verbosity.
      - Removed "tun-cookie" command, which is no longer useful.
    - ovs-controller enhancements for testing various features.
    - New ovs-vlan-test command for testing for Linux kernel driver VLAN
      bugs.  New ovs-vlan-bug-workaround command for enabling and
      disabling a workaround for these driver bugs.
    - OpenFlow support:
      - "Resubmit" actions now update flow statistics.
      - New "register" extension for use in matching and actions, via NXM.
      - New "multipath" experimental action extension.
      - New support for matching multicast Ethernet frames, via NXM.
      - New extension for OpenFlow vendor error codes.
      - New extension to set the QoS output queue without actually
        sending to an output port.
      - Open vSwitch now reports a single flow table, instead of
        separate hash and wildcard tables.  This better models the
        current implementation.
      - New experimental "note" action.
      - New "ofproto/trace" ovs-appctl command and associated utilities
        to ease debugging complex flow tables.
    - Database:
      - Schema documentation now includes an entity-relationship diagram.
      - The database is now garbage collected.  In most tables,
        unreferenced rows will be deleted automatically.
      - Many tables now include statistics updated periodically by
        ovs-vswitchd or ovsdb-server.
      - Every table now has an "external-ids" column for use by OVS
        integrators.
      - There is no default controller anymore.  Each bridge must have its
        controller individually specified.
      - The "fail-mode" is now a property of a Bridge instead of a Controller.
      - New versioning and checksum features.
      - New Managers table and manager_options column in Open_vSwitch table
        for specifying managers.  The old "managers" column in the
        Open_vSwitch table has been removed.
      - Many "name" columns are now immutable.
    - Feature removals:
      - Dropped support for XenServer pre-5.6.100.
      - Dropped support for Linux pre-2.6.18.
      - Dropped controller discovery support.
      - Dropped "ovs-ofctl status" and the OpenFlow extension that it used.
        Statistics reporting in the database is a rough equivalent.
      - Dropped the "corekeeper" package (now separate, at
        http://openvswitch.org/cgi-bin/gitweb.cgi?p=corekeeper).
    - Performance and scalability improvements
    - Bug fixes

v1.1.0pre2 - 13 Sep 2010
------------------------
    - Bug fixes

v1.1.0pre1 - 31 Aug 2010
------------------------
    - OpenFlow 1.0 slicing (QoS) functionality
    - Python bindings for configuration database (no write support)
    - Performance and scalability improvements
    - Bug fixes

v1.0.1 - 31 May 2010
--------------------
    - New "patch" interface type
    - Bug fixes

v1.0.0 - 15 May 2010
--------------------
    - Configuration database with remote management
    - OpenFlow 1.0
    - GRE tunneling
    - Support for XenServer 5.5 and 5.6
    - Performance and scalability improvements
    - Bug fixes

v0.99.2 - 18 Feb 2010
---------------------
    - Bug fixes

v0.99.1 - 25 Jan 2010
---------------------
    - Add support for sFlow(R)
    - Make headers compatible with C++
    - Bug fixes

v0.99.0 - 14 Jan 2010
---------------------
    - User-space forwarding engine
    - Bug fixes

v0.90.7 - 29 Nov 2009
---------------------
    - Add support for NetFlow active timeouts
    - Bug fixes

v0.90.6 - 6 Oct 2009
--------------------
    - Bug fixes

v0.90.5 - 21 Sep 2009
---------------------
    - Generalize in-band control to more diverse network setups
    - Bug fixes