diff --git a/Gemfile.lock b/Gemfile.lock
index bbbe33b..5be8db2 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -3,9 +3,11 @@ PATH
   specs:
     phut (0.7.7)
       activesupport (~> 4.2.6)
+      ffi-yajl (~> 2.2.3)
       gli (~> 2.13.4)
       pio (~> 0.30.0)
       pry (~> 0.10.3)
+      yajl-ruby (~> 1.2.1)
 
 GEM
   remote: https://rubygems.org/
@@ -69,6 +71,8 @@ GEM
     faker (1.6.3)
       i18n (~> 0.5)
     ffi (1.9.10)
+    ffi-yajl (2.2.3)
+      libyajl2 (~> 1.2)
     flay (2.8.0)
       erubis (~> 2.7.0)
       path_expander (~> 1.0)
@@ -113,6 +117,7 @@ GEM
     i18n (0.7.0)
     ice_nine (0.11.2)
     json (1.8.3)
+    libyajl2 (1.2.0)
     listen (3.0.8)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
@@ -133,6 +138,7 @@ GEM
     pio (0.30.0)
       activesupport (~> 4.2, >= 4.2.4)
       bindata (~> 2.1.0)
+      bundler (~> 1.11.2)
     powerpack (0.1.1)
     pry (0.10.3)
       coderay (~> 1.1.0)
@@ -205,6 +211,7 @@ GEM
       coercible (~> 1.0)
       descendants_tracker (~> 0.0, >= 0.0.3)
       equalizer (~> 0.0, >= 0.0.9)
+    yajl-ruby (1.2.1)
     yard (0.8.7.6)
 
 PLATFORMS
diff --git a/features/shell/vswitch#ports.feature b/features/shell/vswitch#ports.feature
index 128bf0c..bccdb87 100644
--- a/features/shell/vswitch#ports.feature
+++ b/features/shell/vswitch#ports.feature
@@ -11,7 +11,10 @@ Feature: Vswitch#ports
   Scenario: Vswitch#ports #=> []
     When I type "vswitch.ports"
     And sleep 5
-    Then the output should contain "[]"
+    Then the output should contain:
+    """
+    []
+    """
 
   @sudo
   Scenario: Vswitch#ports
@@ -20,9 +23,9 @@ Feature: Vswitch#ports
     When I type "vswitch.ports"
     And sleep 5
     Then the output should contain:
-     """
-     ["L0_a"]
-     """
+    """
+    [#<Port number: 1, device: "L0_a">]
+    """
 
   @sudo
   Scenario: Vswitch#ports
@@ -31,6 +34,6 @@ Feature: Vswitch#ports
     When I type "vswitch.ports"
     And sleep 5
     Then the output should contain:
-     """
-     ["L0_a"]
-     """
+    """
+    [#<Port number: 2, device: "L0_a">]
+    """
diff --git a/lib/phut.rb b/lib/phut.rb
index 192c960..1bf5f35 100644
--- a/lib/phut.rb
+++ b/lib/phut.rb
@@ -5,3 +5,4 @@
 require 'phut/version'
 require 'phut/vhost_daemon'
 require 'phut/vswitch'
+require 'phut/ovsdb'
diff --git a/lib/phut/open_vswitch.rb b/lib/phut/open_vswitch.rb
index a3f8add..5b0ebeb 100644
--- a/lib/phut/open_vswitch.rb
+++ b/lib/phut/open_vswitch.rb
@@ -123,6 +123,7 @@ def <=>(other)
     private
 
     def start
+      @vsctl.set_manager
       @vsctl.add_bridge
       @vsctl.set_openflow_version_and_dpid
       @vsctl.controller_tcp_port = @tcp_port
diff --git a/lib/phut/ovsdb.rb b/lib/phut/ovsdb.rb
new file mode 100644
index 0000000..7130591
--- /dev/null
+++ b/lib/phut/ovsdb.rb
@@ -0,0 +1,7 @@
+require 'phut/ovsdb/client'
+require 'phut/ovsdb/transaction'
+
+module Phut
+  # OVSDB client core
+  module OVSDB; end
+end
diff --git a/lib/phut/ovsdb/README.md b/lib/phut/ovsdb/README.md
new file mode 100644
index 0000000..929d58a
--- /dev/null
+++ b/lib/phut/ovsdb/README.md
@@ -0,0 +1,100 @@
+
+Primitive OVSDB client implementation
+===
+
+Supports [RFC7047](https://tools.ietf.org/html/rfc7047).
+
+## Examples
+
+### Transaction
+
+* Create Bridge
+
+```ruby
+require 'active_flow'
+
+class OVSDBTest
+  extend ActiveFlow::OVSDB::Transact
+
+  def self.create_bridge(name, ofc_target, bridge_options = {})
+    client = ActiveFlow::OVSDB::Client.new('localhost', 6632)
+    ovs_rows_query = select('Open_vSwitch', [], [:_uuid, :bridges])
+    ovs_row = client.transact(1, 'Open_vSwitch', [ovs_rows_query]).first[:rows].first
+    ovs_bridges = ovs_row[:bridges]
+    new_ovs_bridges = case ovs_bridges.include?('set')
+                      when true
+                        ovs_bridges_content = ovs_bridges[1]
+                        case ovs_bridges_content.empty?
+                        when true
+                          ['named-uuid', "bridge_br_#{name}"]
+                        else
+                          ['set', ovs_bridges_content << ['named-uuid', "bridge_br_#{name}"]]
+                        end
+                      else
+                        ovs_bridges_content = ovs_bridges[1]
+                        ['set', [ovs_bridges_content] << ['named-uuid', "bridge_br_#{name}"]]
+                      end
+    ovs_uuid = ovs_row[:_uuid]
+    interface = { name: "br-#{name}", type: "internal" }
+    port = { name: "br-#{name}", interfaces: ['named-uuid', "interface_br_#{name}"] }
+    controller = { target: ofc_target }
+    bridge = { name: "br-#{name}", ports: ['named-uuid', "port_br_#{name}"], controller: ['named-uuid', "ofc_br_#{name}"], protocols: 'OpenFlow10' }
+    transactions = [
+      insert('Interface', interface, "interface_br_#{name}"),
+      insert('Port', port, "port_br_#{name}"),
+      insert('Controller', controller, "ofc_br_#{name}"),
+      insert('Bridge', bridge, "bridge_br_#{name}"),
+      update('Open_vSwitch', [[:_uuid, :==, ovs_uuid]], { bridges: new_ovs_bridges }),
+      mutate('Open_vSwitch', [[:_uuid, :==, ovs_uuid]], [[:next_cfg, '+=', 1]])
+    ]
+    client.transact(1, 'Open_vSwitch', transactions)
+    transactions = [
+      update('Bridge', [[:name, :==, "br-#{name}"]], { other_config: [:map, bridge_options.to_a] }),
+      mutate('Open_vSwitch', [[:_uuid, :==, ovs_uuid]], [[:next_cfg, '+=', 1]])
+    ]
+    client.transact(1, 'Open_vSwitch', transactions)
+  end
+
+  def self.connect_with_patch(br1, br2)
+    patch_br1 = "patch-#{br1}"
+    patch_br2 = "patch-#{br2}"
+    client = ActiveFlow::OVSDB::Client.new('localhost', 6632)
+    ovs_rows_query = select('Open_vSwitch', [], [:_uuid])
+    ovs_row = client.transact(1, 'Open_vSwitch', [ovs_rows_query]).first[:rows].first
+    ovs_uuid = ovs_row[:_uuid]
+    selects = [
+      select('Bridge', [[:name, :==, br1]], [:ports]),
+      select('Bridge', [[:name, :==, br2]], [:ports])
+    ]
+    br1_ports, br2_ports = client.transact(1, 'Open_vSwitch', selects)
+    new_br1_ports = br1_ports.map do |_, item|
+      ports = item[0][:ports].include?('set') ? item[0][:ports][1] : [item[0][:ports]]
+      [:set, ports << ['named-uuid', :patch_br1]]
+    end.first
+    new_br2_ports = br2_ports.map do |_, item|
+      ports = item[0][:ports].include?('set') ? item[0][:ports][1] : [item[0][:ports]]
+      [:set, ports << ['named-uuid', :patch_br2]]
+    end.first
+
+    patch_br1_port = {name: patch_br1, interfaces: ['named-uuid', :patch_br1_iface]}
+    patch_br2_port = {name: patch_br2, interfaces: ['named-uuid', :patch_br2_iface]}
+
+    patch_br1_iface = {name: patch_br1, type: :patch, options: [:map, {peer: patch_br2}.to_a]}
+    patch_br2_iface = {name: patch_br2, type: :patch, options: [:map, {peer: patch_br1}.to_a]}
+
+    transactions = [
+      insert('Interface', patch_br1_iface, :patch_br1_iface),
+      insert('Interface', patch_br2_iface, :patch_br2_iface),
+      insert('Port', patch_br1_port, :patch_br1),
+      insert('Port', patch_br2_port, :patch_br2),
+      update('Bridge', [[:name, :==, br1]], { ports: new_br1_ports }),
+      update('Bridge', [[:name, :==, br2]], { ports: new_br2_ports }),
+      mutate('Open_vSwitch', [[:_uuid, :==, ovs_uuid]], [[:next_cfg, '+=', 1]])
+    ]
+    client.transact(1, 'Open_vSwitch', transactions)
+  end
+end
+
+# OVSDBTest.create_bridge('def', 'tcp:127.0.0.1:6653', 'datapath-id' => '0000000000000def')
+# OVSDBTest.connect_with_patch('nts0xabc', 'br-def')
+```
diff --git a/lib/phut/ovsdb/client.rb b/lib/phut/ovsdb/client.rb
new file mode 100644
index 0000000..c9510b2
--- /dev/null
+++ b/lib/phut/ovsdb/client.rb
@@ -0,0 +1,74 @@
+require 'phut/ovsdb/method'
+require 'phut/ovsdb/transport'
+require 'yajl'
+
+module Phut
+  module OVSDB
+    # OVSDB Client core
+    class Client
+      include Phut::OVSDB::Method
+
+      attr_reader :transport
+      attr_reader :database
+
+      def initialize(host, port, options = {})
+        @mut = Mutex.new
+        @queue = Queue.new
+        @transport = Transport.new(host, port, self, options)
+        @database = options.fetch(:database, nil)
+        initialize_codec
+      end
+
+      def handle_tcp(data)
+        @parser << data
+      end
+
+      def handle_message(data)
+        case data[:method]
+        when 'echo'
+          echo_reply
+        else
+          maybe_handle_reply(data)
+        end
+      end
+
+      private
+
+      def maybe_handle_reply(data)
+        id = data[:id]
+        case id
+        when 'echo'
+          :noop
+        else
+          @queue.enq(data)
+        end
+      end
+
+      def initialize_codec
+        @parser = Yajl::Parser.new(symbolize_keys: true)
+        @parser.on_parse_complete = method(:handle_message)
+        @encoder = Yajl::Encoder.new
+      end
+
+      def json_async_send(jsonable)
+        json_data = @encoder.encode(jsonable)
+        transport.send(json_data)
+      end
+
+      def json_send(jsonable)
+        json_async_send(jsonable)
+        th = Thread.new do
+          result = nil
+          continue = true
+          while continue
+            next if @queue.empty?
+            @mut.synchronize { result = @queue.deq }
+            continue = false
+          end
+          result
+        end
+        th.join.value
+      end
+    end
+  end
+end
diff --git a/lib/phut/ovsdb/method.rb b/lib/phut/ovsdb/method.rb
new file mode 100644
index 0000000..b9acb40
--- /dev/null
+++ b/lib/phut/ovsdb/method.rb
@@ -0,0 +1,26 @@
+require 'e2mmap'
+
+module Phut
+  module OVSDB
+    # OVSDB methods
+    module Method
+      extend Exception2MessageMapper
+
+      def_exception :GetSchemaError, '%s'
+      def_exception :TransactionError, '%s'
+
+      def echo_reply
+        json_async_send(id: 'echo', result: [], error: nil)
+      end
+
+      def transact(id, db_name, operations)
+        data = json_send(
+          id: id,
+          method: 'transact',
+          params: [db_name, *operations]
+        )
+        data[:result]
+      end
+    end
+  end
+end
diff --git a/lib/phut/ovsdb/transaction.rb b/lib/phut/ovsdb/transaction.rb
new file mode 100644
index 0000000..1502aab
--- /dev/null
+++ b/lib/phut/ovsdb/transaction.rb
@@ -0,0 +1,92 @@
+module Phut
+  module OVSDB
+    # Transaction
+    module Transaction
+      def select(table, conds, cols = nil)
+        select = {
+          op: :select,
+          table: table,
+          where: Array(conds)
+        }
+        select = { columns: Array(cols) }.merge(select) if cols
+        select
+      end
+
+      def insert(table, row, uuid_name = nil)
+        insert = {
+          op: :insert,
+          table: table,
+          row: row
+        }
+        insert = { 'uuid-name' => uuid_name }.merge(insert) if uuid_name
+        insert
+      end
+
+      def update(table, conds, row)
+        {
+          op: :update,
+          table: table,
+          where: Array(conds),
+          row: row
+        }
+      end
+
+      def delete(table, conds)
+        {
+          op: :delete,
+          table: table,
+          where: Array(conds)
+        }
+      end
+
+      def mutate(table, conds, mutes)
+        {
+          op: :mutate,
+          table: table,
+          where: Array(conds),
+          mutations: Array(mutes)
+        }
+      end
+
+      def commit(mode = true)
+        {
+          op: :commit,
+          durable: mode
+        }
+      end
+
+      def abort
+        {
+          op: :abort
+        }
+      end
+
+      def wait(table, cond, cols, until_cond, rows, timeout = nil)
+        wait = {
+          op: :wait,
+          table: table,
+          where: Array(cond),
+          columns: Array(cols),
+          until: until_cond,
+          rows: Array(rows)
+        }
+        wait = { timeout: timeout }.merge(wait) if timeout
+        wait
+      end
+
+      def comment(string)
+        {
+          op: :comment,
+          comment: string
+        }
+      end
+
+      def assert(lock_id)
+        {
+          op: :assert,
+          lock: lock_id
+        }
+      end
+    end
+  end
+end
diff --git a/lib/phut/ovsdb/transport.rb b/lib/phut/ovsdb/transport.rb
new file mode 100644
index 0000000..0444f6c
--- /dev/null
+++ b/lib/phut/ovsdb/transport.rb
@@ -0,0 +1,77 @@
+require 'socket'
+
+module Phut
+  module OVSDB
+    # OVSDB Transport Class
+    class Transport
+      attr_reader :host
+      attr_reader :port
+      attr_reader :options
+      attr_reader :callback
+
+      def initialize(host, port, klass, options = {})
+        @options = options
+        @host = host
+        @port = port
+        @callback = klass.method(:handle_tcp)
+        signal_connect
+        enter_loop
+      end
+
+      def send(data)
+        @socket.write(data)
+      rescue Errno::EPIPE
+        signal_connect
+      end
+
+      def read
+        @socket.readpartial(1000)
+      end
+
+      private
+
+      def enter_loop
+        Thread.abort_on_exception = true
+        Thread.new do
+          loop do
+            begin
+              handle_connection
+            rescue => error
+              raise error
+            end
+          end
+        end
+      end
+
+      def signal_connect
+        count = count.to_i + 1
+        @socket = TCPSocket.open(host, port)
+      rescue => error
+        sleep reconnect_interval
+        should_reconnect?(count) ? retry : raise(error)
+      end
+
+      def should_reconnect?(count)
+        (reconnect && (reconnect_retry_limit > count))
+      end
+
+      def handle_connection
+        callback.call(read)
+      rescue EOFError
+        signal_connect
+      end
+
+      def reconnect
+        options[:reconnect] ||= false
+      end
+
+      def reconnect_interval
+        options[:reconnect_interval] ||= 5
+      end
+
+      def reconnect_retry_limit
+        options[:reconnect_retry_limit] ||= 10
+      end
+    end
+  end
+end
diff --git a/lib/phut/port.rb b/lib/phut/port.rb
new file mode 100644
index 0000000..388198e
--- /dev/null
+++ b/lib/phut/port.rb
@@ -0,0 +1,21 @@
+module Phut
+  # OpenvSwitch Port class
+  class Port
+
+    attr_reader :device
+    attr_reader :number
+
+    def initialize(device:, number:)
+      @device = device
+      @number = number
+    end
+
+    def inspect
+      "#<Port number: #{number}, device: \"#{device}\">"
+    end
+
+    def to_s
+      "port (number = #{number}, device = #{device})"
+    end
+  end
+end
diff --git a/lib/phut/vsctl.rb b/lib/phut/vsctl.rb
index 9b7e829..de41c81 100644
--- a/lib/phut/vsctl.rb
+++ b/lib/phut/vsctl.rb
@@ -1,11 +1,15 @@
 # frozen_string_literal: true
 require 'phut/shell_runner'
+require 'phut/ovsdb'
+require 'phut/port'
 require 'pio'
 
 module Phut
   # ovs-vsctl wrapper
   class Vsctl
     extend ShellRunner
+    include Phut::OVSDB::Transaction
+    extend Phut::OVSDB::Transaction
 
     def self.list_br(prefix)
       sudo('ovs-vsctl list-br').split.each_with_object([]) do |each, list|
@@ -18,6 +22,7 @@ def self.list_br(prefix)
     include ShellRunner
 
     def initialize(name:, name_prefix:, dpid:, bridge:)
+      @client = Phut::OVSDB::Client.new('localhost', 6632)
       @name = name
       @prefix = name_prefix
       @dpid = dpid
@@ -30,12 +35,16 @@ def tcp_port
     end
 
     def add_bridge
-      sudo "ovs-vsctl add-br #{@bridge}"
+      sudo "ovs-vsctl --may-exist add-br #{@bridge}"
       sudo "/sbin/sysctl -w net.ipv6.conf.#{@bridge}.disable_ipv6=1 -q"
     end
 
     def del_bridge
-      sudo "ovs-vsctl del-br #{@bridge}"
+      sudo "ovs-vsctl --if-exists del-br #{@bridge}"
+    end
+
+    def set_manager
+      sudo 'ovs-vsctl set-manager ptcp:6632'
     end
 
     def set_openflow_version_and_dpid
@@ -55,14 +64,14 @@ def set_fail_mode_secure
     end
 
     def add_port(device)
-      sudo "ovs-vsctl add-port #{@bridge} #{device}"
+      sudo "ovs-vsctl --may-exist add-port #{@bridge} #{device}"
       nil
     end
 
     def add_numbered_port(port_number, device)
       add_port device
-      sudo "ovs-vsctl set Port #{device} "\
-           "other_config:rstp-port-num=#{port_number}"
+      sudo "ovs-vsctl set Interface #{device} "\
+           "ofport_request=#{port_number}"
       nil
     end
 
@@ -75,7 +84,31 @@ def bring_port_down(port_number)
     end
 
     def ports
-      sudo("ovs-vsctl list-ports #{@bridge}").split
+      br_query = [select('Bridge', [[:name, :==, @bridge]], [:ports])]
+      br_ports = @client.transact(1, 'Open_vSwitch', br_query)
+      if br_ports.first[:rows].first
+        br_ports = br_ports.first[:rows].first[:ports]
+        ports = if br_ports.include? "set"
+                  br_ports[1]
+                else
+                  [br_ports]
+                end
+        port_query = ports.map do |port|
+          select('Port', [[:_uuid, :==, port]], [:name])
+        end
+        iface_query = @client.transact(1, 'Open_vSwitch', port_query).map do |iface|
+          select('Interface', [[:name, :==, iface[:rows].first[:name]],
+                               [:name, :!=, @bridge]], [:ofport, :name])
+        end
+        @client.transact(1, 'Open_vSwitch', iface_query).map do |iface|
+          next unless iface[:rows].first.respond_to?(:[])
+          device = iface[:rows].first[:name]
+          number = iface[:rows].first[:ofport]
+          Phut::Port.new(device: device, number: number)
+        end.compact
+      else
+        []
+      end
     end
 
     private
diff --git a/phut.gemspec b/phut.gemspec
index cb1c959..c45cd32 100644
--- a/phut.gemspec
+++ b/phut.gemspec
@@ -28,4 +28,6 @@ Gem::Specification.new do |gem|
   gem.add_dependency 'gli', '~> 2.13.4'
   gem.add_dependency 'pio', '~> 0.30.0'
   gem.add_dependency 'pry', '~> 0.10.3'
+  gem.add_dependency 'ffi-yajl', '~> 2.2.3'
+  gem.add_dependency 'yajl-ruby', '~> 1.2.1'
 end