diff --git a/openflow/ctl/src/main/java/org/onlab/onos/of/controller/impl/OFChannelHandler.java b/openflow/ctl/src/main/java/org/onlab/onos/of/controller/impl/OFChannelHandler.java
new file mode 100644
index 0000000..adcb990
--- /dev/null
+++ b/openflow/ctl/src/main/java/org/onlab/onos/of/controller/impl/OFChannelHandler.java
@@ -0,0 +1,1225 @@
+//CHECKSTYLE:OFF
+package org.onlab.onos.of.controller.impl;
+
+import java.io.IOException;
+import java.nio.channels.ClosedChannelException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.RejectedExecutionException;
+
+import org.jboss.netty.channel.Channel;
+import org.jboss.netty.channel.ChannelHandlerContext;
+import org.jboss.netty.channel.ChannelStateEvent;
+import org.jboss.netty.channel.ExceptionEvent;
+import org.jboss.netty.channel.MessageEvent;
+import org.jboss.netty.handler.timeout.IdleStateAwareChannelHandler;
+import org.jboss.netty.handler.timeout.IdleStateEvent;
+import org.jboss.netty.handler.timeout.ReadTimeoutException;
+import org.onlab.onos.of.controller.driver.OpenFlowSwitchDriver;
+import org.onlab.onos.of.controller.driver.SwitchStateException;
+import org.projectfloodlight.openflow.exceptions.OFParseError;
+import org.projectfloodlight.openflow.protocol.OFAsyncGetReply;
+import org.projectfloodlight.openflow.protocol.OFBadRequestCode;
+import org.projectfloodlight.openflow.protocol.OFBarrierReply;
+import org.projectfloodlight.openflow.protocol.OFBarrierRequest;
+import org.projectfloodlight.openflow.protocol.OFDescStatsReply;
+import org.projectfloodlight.openflow.protocol.OFDescStatsRequest;
+import org.projectfloodlight.openflow.protocol.OFEchoReply;
+import org.projectfloodlight.openflow.protocol.OFEchoRequest;
+import org.projectfloodlight.openflow.protocol.OFErrorMsg;
+import org.projectfloodlight.openflow.protocol.OFErrorType;
+import org.projectfloodlight.openflow.protocol.OFExperimenter;
+import org.projectfloodlight.openflow.protocol.OFFactory;
+import org.projectfloodlight.openflow.protocol.OFFeaturesReply;
+import org.projectfloodlight.openflow.protocol.OFFlowModFailedCode;
+import org.projectfloodlight.openflow.protocol.OFFlowRemoved;
+import org.projectfloodlight.openflow.protocol.OFGetConfigReply;
+import org.projectfloodlight.openflow.protocol.OFGetConfigRequest;
+import org.projectfloodlight.openflow.protocol.OFHello;
+import org.projectfloodlight.openflow.protocol.OFHelloElem;
+import org.projectfloodlight.openflow.protocol.OFMessage;
+import org.projectfloodlight.openflow.protocol.OFPacketIn;
+import org.projectfloodlight.openflow.protocol.OFPortDescStatsReply;
+import org.projectfloodlight.openflow.protocol.OFPortDescStatsRequest;
+import org.projectfloodlight.openflow.protocol.OFPortStatus;
+import org.projectfloodlight.openflow.protocol.OFQueueGetConfigReply;
+import org.projectfloodlight.openflow.protocol.OFRoleReply;
+import org.projectfloodlight.openflow.protocol.OFSetConfig;
+import org.projectfloodlight.openflow.protocol.OFStatsReply;
+import org.projectfloodlight.openflow.protocol.OFStatsReplyFlags;
+import org.projectfloodlight.openflow.protocol.OFStatsType;
+import org.projectfloodlight.openflow.protocol.OFType;
+import org.projectfloodlight.openflow.protocol.OFVersion;
+import org.projectfloodlight.openflow.protocol.errormsg.OFBadRequestErrorMsg;
+import org.projectfloodlight.openflow.protocol.errormsg.OFFlowModFailedErrorMsg;
+import org.projectfloodlight.openflow.types.U32;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Channel handler deals with the switch connection and dispatches
+ * switch messages to the appropriate locations.
+ */
+class OFChannelHandler extends IdleStateAwareChannelHandler {
+    private static final Logger log = LoggerFactory.getLogger(OFChannelHandler.class);
+    private final Controller controller;
+    private OpenFlowSwitchDriver sw;
+    private long thisdpid; // channelHandler cached value of connected switch id
+    private Channel channel;
+    // State needs to be volatile because the HandshakeTimeoutHandler
+    // needs to check if the handshake is complete
+    private volatile ChannelState state;
+
+    // When a switch with a duplicate dpid is found (i.e we already have a
+    // connected switch with the same dpid), the new switch is immediately
+    // disconnected. At that point netty callsback channelDisconnected() which
+    // proceeds to cleaup switch state - we need to ensure that it does not cleanup
+    // switch state for the older (still connected) switch
+    private volatile Boolean duplicateDpidFound;
+
+    // Temporary storage for switch-features and port-description
+    private OFFeaturesReply featuresReply;
+    private OFPortDescStatsReply portDescReply;
+    // a concurrent ArrayList to temporarily store port status messages
+    // before we are ready to deal with them
+    private final CopyOnWriteArrayList<OFPortStatus> pendingPortStatusMsg;
+
+    //Indicates the openflow version used by this switch
+    protected OFVersion ofVersion;
+    protected OFFactory factory13;
+    protected OFFactory factory10;
+
+    /** transaction Ids to use during handshake. Since only one thread
+     * calls into an OFChannelHandler instance, we don't need atomic.
+     * We will count down
+     */
+    private int handshakeTransactionIds = -1;
+
+    /**
+     * Create a new unconnected OFChannelHandler.
+     * @param controller
+     */
+    OFChannelHandler(Controller controller) {
+        this.controller = controller;
+        this.state = ChannelState.INIT;
+        this.pendingPortStatusMsg = new CopyOnWriteArrayList<OFPortStatus>();
+        factory13 = controller.getOFMessageFactory13();
+        factory10 = controller.getOFMessageFactory10();
+        duplicateDpidFound = Boolean.FALSE;
+    }
+
+
+
+    // XXX S consider if necessary
+    public void disconnectSwitch() {
+        sw.disconnectSwitch();
+    }
+
+
+
+    //*************************
+    //  Channel State Machine
+    //*************************
+
+    /**
+     * The state machine for handling the switch/channel state. All state
+     * transitions should happen from within the state machine (and not from other
+     * parts of the code)
+     */
+    enum ChannelState {
+        /**
+         * Initial state before channel is connected.
+         */
+        INIT(false) {
+            @Override
+            void processOFMessage(OFChannelHandler h, OFMessage m)
+                    throws IOException, SwitchStateException {
+                illegalMessageReceived(h, m);
+            }
+
+            @Override
+            void processOFError(OFChannelHandler h, OFErrorMsg m)
+                    throws IOException {
+                // need to implement since its abstract but it will never
+                // be called
+            }
+
+            @Override
+            void processOFPortStatus(OFChannelHandler h, OFPortStatus m)
+                    throws IOException {
+                unhandledMessageReceived(h, m);
+            }
+        },
+
+        /**
+         * We send a OF 1.3 HELLO to the switch and wait for a Hello from the switch.
+         * Once we receive the reply, we decide on OF 1.3 or 1.0 switch - no other
+         * protocol version is accepted.
+         * We send an OFFeaturesRequest depending on the protocol version selected
+         * Next state is WAIT_FEATURES_REPLY
+         */
+        WAIT_HELLO(false) {
+            @Override
+            void processOFHello(OFChannelHandler h, OFHello m)
+                    throws IOException {
+                // TODO We could check for the optional bitmap, but for now
+                // we are just checking the version number.
+                if (m.getVersion() == OFVersion.OF_13) {
+                    log.info("Received {} Hello from {}", m.getVersion(),
+                            h.channel.getRemoteAddress());
+                    h.ofVersion = OFVersion.OF_13;
+                } else if (m.getVersion() == OFVersion.OF_10) {
+                    log.info("Received {} Hello from {} - switching to OF "
+                            + "version 1.0", m.getVersion(),
+                            h.channel.getRemoteAddress());
+                    h.ofVersion = OFVersion.OF_10;
+                } else {
+                    log.error("Received Hello of version {} from switch at {}. "
+                            + "This controller works with OF1.0 and OF1.3 "
+                            + "switches. Disconnecting switch ...",
+                            m.getVersion(), h.channel.getRemoteAddress());
+                    h.channel.disconnect();
+                    return;
+                }
+                h.sendHandshakeFeaturesRequestMessage();
+                h.setState(WAIT_FEATURES_REPLY);
+            }
+            @Override
+            void processOFFeaturesReply(OFChannelHandler h, OFFeaturesReply  m)
+                    throws IOException, SwitchStateException {
+                illegalMessageReceived(h, m);
+            }
+            @Override
+            void processOFStatisticsReply(OFChannelHandler h,
+                    OFStatsReply  m)
+                            throws IOException, SwitchStateException {
+                illegalMessageReceived(h, m);
+            }
+            @Override
+            void processOFError(OFChannelHandler h, OFErrorMsg m) {
+                logErrorDisconnect(h, m);
+            }
+
+            @Override
+            void processOFPortStatus(OFChannelHandler h, OFPortStatus m)
+                    throws IOException {
+                unhandledMessageReceived(h, m);
+            }
+        },
+
+
+        /**
+         * We are waiting for a features reply message. Once we receive it, the
+         * behavior depends on whether this is a 1.0 or 1.3 switch. For 1.0,
+         * we send a SetConfig request, barrier, and GetConfig request and the
+         * next state is WAIT_CONFIG_REPLY. For 1.3, we send a Port description
+         * request and the next state is WAIT_PORT_DESC_REPLY.
+         */
+        WAIT_FEATURES_REPLY(false) {
+            @Override
+            void processOFFeaturesReply(OFChannelHandler h, OFFeaturesReply  m)
+                    throws IOException {
+                h.thisdpid = m.getDatapathId().getLong();
+                log.info("Received features reply for switch at {} with dpid {}",
+                        h.getSwitchInfoString(), h.thisdpid);
+
+                h.featuresReply = m; //temp store
+                if (h.ofVersion == OFVersion.OF_10) {
+                    h.sendHandshakeSetConfig();
+                    h.setState(WAIT_CONFIG_REPLY);
+                } else {
+                    //version is 1.3, must get switchport information
+                    h.sendHandshakeOFPortDescRequest();
+                    h.setState(WAIT_PORT_DESC_REPLY);
+                }
+            }
+            @Override
+            void processOFStatisticsReply(OFChannelHandler h,
+                    OFStatsReply  m)
+                            throws IOException, SwitchStateException {
+                illegalMessageReceived(h, m);
+            }
+            @Override
+            void processOFError(OFChannelHandler h, OFErrorMsg m) {
+                logErrorDisconnect(h, m);
+            }
+
+            @Override
+            void processOFPortStatus(OFChannelHandler h, OFPortStatus m)
+                    throws IOException {
+                unhandledMessageReceived(h, m);
+            }
+        },
+
+        /**
+         * We are waiting for a description of the 1.3 switch ports.
+         * Once received, we send a SetConfig request
+         * Next State is WAIT_CONFIG_REPLY
+         */
+        WAIT_PORT_DESC_REPLY(false) {
+
+            @Override
+            void processOFStatisticsReply(OFChannelHandler h, OFStatsReply m)
+                    throws SwitchStateException {
+                // Read port description
+                if (m.getStatsType() != OFStatsType.PORT_DESC) {
+                    log.warn("Expecting port description stats but received stats "
+                            + "type {} from {}. Ignoring ...", m.getStatsType(),
+                            h.channel.getRemoteAddress());
+                    return;
+                }
+                if (m.getFlags().contains(OFStatsReplyFlags.REPLY_MORE)) {
+                    log.warn("Stats reply indicates more stats from sw {} for "
+                            + "port description - not currently handled",
+                            h.getSwitchInfoString());
+                }
+                h.portDescReply = (OFPortDescStatsReply) m; // temp store
+                log.info("Received port desc reply for switch at {}",
+                        h.getSwitchInfoString());
+                try {
+                    h.sendHandshakeSetConfig();
+                } catch (IOException e) {
+                    log.error("Unable to send setConfig after PortDescReply. "
+                            + "Error: {}", e.getMessage());
+                }
+                h.setState(WAIT_CONFIG_REPLY);
+            }
+
+            @Override
+            void processOFError(OFChannelHandler h, OFErrorMsg m)
+                    throws IOException, SwitchStateException {
+                logErrorDisconnect(h, m);
+
+            }
+
+            @Override
+            void processOFPortStatus(OFChannelHandler h, OFPortStatus m)
+                    throws IOException, SwitchStateException {
+                unhandledMessageReceived(h, m);
+
+            }
+        },
+
+        /**
+         * We are waiting for a config reply message. Once we receive it
+         * we send a DescriptionStatsRequest to the switch.
+         * Next state: WAIT_DESCRIPTION_STAT_REPLY
+         */
+        WAIT_CONFIG_REPLY(false) {
+            @Override
+            void processOFGetConfigReply(OFChannelHandler h, OFGetConfigReply m)
+                    throws IOException {
+                if (m.getMissSendLen() == 0xffff) {
+                    log.trace("Config Reply from switch {} confirms "
+                            + "miss length set to 0xffff",
+                            h.getSwitchInfoString());
+                } else {
+                    // FIXME: we can't really deal with switches that don't send
+                    // full packets. Shouldn't we drop the connection here?
+                    log.warn("Config Reply from switch {} has"
+                            + "miss length set to {}",
+                            h.getSwitchInfoString(),
+                            m.getMissSendLen());
+                }
+                h.sendHandshakeDescriptionStatsRequest();
+                h.setState(WAIT_DESCRIPTION_STAT_REPLY);
+            }
+
+            @Override
+            void processOFBarrierReply(OFChannelHandler h, OFBarrierReply m) {
+                // do nothing;
+            }
+
+            @Override
+            void processOFFeaturesReply(OFChannelHandler h, OFFeaturesReply  m)
+                    throws IOException, SwitchStateException {
+                illegalMessageReceived(h, m);
+            }
+            @Override
+            void processOFStatisticsReply(OFChannelHandler h,
+                    OFStatsReply  m)
+                            throws IOException, SwitchStateException {
+                log.error("Received multipart(stats) message sub-type {}",
+                        m.getStatsType());
+                illegalMessageReceived(h, m);
+            }
+
+            @Override
+            void processOFError(OFChannelHandler h, OFErrorMsg m) {
+                logErrorDisconnect(h, m);
+            }
+
+            @Override
+            void processOFPortStatus(OFChannelHandler h, OFPortStatus m)
+                    throws IOException {
+                h.pendingPortStatusMsg.add(m);
+            }
+        },
+
+
+        /**
+         * We are waiting for a OFDescriptionStat message from the switch.
+         * Once we receive any stat message we try to parse it. If it's not
+         * a description stats message we disconnect. If its the expected
+         * description stats message, we:
+         *    - use the switch driver to bind the switch and get an IOFSwitch instance
+         *    - setup the IOFSwitch instance
+         *    - add switch controller and send the initial role
+         *      request to the switch.
+         * Next state: WAIT_INITIAL_ROLE
+         *      In the typical case, where switches support role request messages
+         *      the next state is where we expect the role reply message.
+         *      In the special case that where the switch does not support any kind
+         *      of role request messages, we don't send a role message, but we do
+         *      request mastership from the registry service. This controller
+         *      should become master once we hear back from the registry service.
+         * All following states will have a h.sw instance!
+         */
+        WAIT_DESCRIPTION_STAT_REPLY(false) {
+            @Override
+            void processOFStatisticsReply(OFChannelHandler h, OFStatsReply m)
+                    throws SwitchStateException {
+                // Read description, if it has been updated
+                if (m.getStatsType() != OFStatsType.DESC) {
+                    log.warn("Expecting Description stats but received stats "
+                            + "type {} from {}. Ignoring ...", m.getStatsType(),
+                            h.channel.getRemoteAddress());
+                    return;
+                }
+                log.info("Received switch description reply from switch at {}",
+                        h.channel.getRemoteAddress());
+                OFDescStatsReply drep = (OFDescStatsReply) m;
+                // Here is where we differentiate between different kinds of switches
+                h.sw = h.controller.getOFSwitchInstance(h.thisdpid, drep, h.ofVersion);
+
+                h.sw.setOFVersion(h.ofVersion);
+                h.sw.setFeaturesReply(h.featuresReply);
+                h.sw.setPortDescReply(h.portDescReply);
+                h.sw.setConnected(true);
+                h.sw.setChannel(h.channel);
+                boolean success = h.sw.connectSwitch();
+
+                if (!success) {
+                    disconnectDuplicate(h);
+                    return;
+                }
+                // set switch information
+
+
+
+                log.info("Switch {} bound to class {}, description {}",
+                        new Object[] {h.sw, h.sw.getClass(), drep });
+                //Put switch in EQUAL mode until we hear back from the global registry
+                //log.debug("Setting new switch {} to EQUAL and sending Role request",
+                //        h.sw.getStringId());
+                //h.sw.activateEqualSwitch();
+                //h.setSwitchRole(RoleState.EQUAL);
+
+                h.sw.startDriverHandshake();
+                h.setState(WAIT_SWITCH_DRIVER_SUB_HANDSHAKE);
+
+            }
+
+            @Override
+            void processOFError(OFChannelHandler h, OFErrorMsg m) {
+                logErrorDisconnect(h, m);
+            }
+
+            @Override
+            void processOFFeaturesReply(OFChannelHandler h, OFFeaturesReply  m)
+                    throws IOException, SwitchStateException {
+                illegalMessageReceived(h, m);
+            }
+
+            @Override
+            void processOFPortStatus(OFChannelHandler h, OFPortStatus m)
+                    throws IOException {
+                h.pendingPortStatusMsg.add(m);
+            }
+        },
+
+
+        /**
+         * We are waiting for the respective switch driver to complete its
+         * configuration. Notice that we do not consider this to be part of the main
+         * switch-controller handshake. But we do consider it as a step that comes
+         * before we declare the switch as available to the controller.
+         * Next State: depends on the role of this controller for this switch - either
+         * MASTER or EQUAL.
+         */
+        WAIT_SWITCH_DRIVER_SUB_HANDSHAKE(true) {
+
+            @Override
+            void processOFError(OFChannelHandler h, OFErrorMsg m)
+                    throws IOException {
+                // will never be called. We override processOFMessage
+            }
+
+            @Override
+            void processOFMessage(OFChannelHandler h, OFMessage m)
+                    throws IOException, SwitchStateException {
+                if (m.getType() == OFType.ECHO_REQUEST) {
+                    processOFEchoRequest(h, (OFEchoRequest) m);
+                } else if (m.getType() == OFType.ROLE_REPLY) {
+                    h.sw.handleRole(m);
+                } else if (m.getType() == OFType.ERROR) {
+                    if (!h.sw.handleRoleError((OFErrorMsg)m)) {
+                        h.sw.processDriverHandshakeMessage(m);
+                        if (h.sw.isDriverHandshakeComplete()) {
+                            h.setState(ACTIVE);
+                        }
+                    }
+                } else {
+                    if (m.getType() == OFType.EXPERIMENTER &&
+                            ((OFExperimenter) m).getExperimenter() ==
+                            RoleManager.NICIRA_EXPERIMENTER) {
+                        h.sw.handleNiciraRole(m);
+                    } else {
+                        h.sw.processDriverHandshakeMessage(m);
+                        if (h.sw.isDriverHandshakeComplete()) {
+                            h.setState(ACTIVE);
+                        }
+                    }
+                }
+            }
+
+            @Override
+            void processOFPortStatus(OFChannelHandler h, OFPortStatus m)
+                    throws IOException, SwitchStateException {
+                h.pendingPortStatusMsg.add(m);
+            }
+        },
+
+
+        /**
+         * This controller is in MASTER role for this switch. We enter this state
+         * after requesting and winning control from the global registry.
+         * The main handshake as well as the switch-driver sub-handshake
+         * is complete at this point.
+         * // XXX S reconsider below
+         * In the (near) future we may deterministically assign controllers to
+         * switches at startup.
+         * We only leave this state if the switch disconnects or
+         * if we send a role request for SLAVE /and/ receive the role reply for
+         * SLAVE.
+         */
+        ACTIVE(true) {
+            @Override
+            void processOFError(OFChannelHandler h, OFErrorMsg m)
+                    throws IOException, SwitchStateException {
+                // if we get here, then the error message is for something else
+                if (m.getErrType() == OFErrorType.BAD_REQUEST &&
+                        ((OFBadRequestErrorMsg) m).getCode() ==
+                        OFBadRequestCode.EPERM) {
+                    // We are the master controller and the switch returned
+                    // a permission error. This is a likely indicator that
+                    // the switch thinks we are slave. Reassert our
+                    // role
+                    // FIXME: this could be really bad during role transitions
+                    // if two controllers are master (even if its only for
+                    // a brief period). We might need to see if these errors
+                    // persist before we reassert
+                    log.warn("Received permission error from switch {} while" +
+                            "being master. Reasserting master role.",
+                            h.getSwitchInfoString());
+                    h.sw.reassertRole();
+                } else if (m.getErrType() == OFErrorType.FLOW_MOD_FAILED &&
+                        ((OFFlowModFailedErrorMsg) m).getCode() ==
+                        OFFlowModFailedCode.ALL_TABLES_FULL) {
+                    h.sw.setTableFull(true);
+                } else {
+                    logError(h, m);
+                }
+                h.dispatchMessage(m);
+            }
+
+            @Override
+            void processOFStatisticsReply(OFChannelHandler h,
+                    OFStatsReply m) {
+                h.dispatchMessage(m);
+            }
+
+            @Override
+            void processOFExperimenter(OFChannelHandler h, OFExperimenter m)
+                    throws SwitchStateException {
+                h.sw.handleNiciraRole(m);
+            }
+
+            @Override
+            void processOFRoleReply(OFChannelHandler h, OFRoleReply m)
+                    throws SwitchStateException {
+                h.sw.handleRole(m);
+            }
+
+            @Override
+            void processOFPortStatus(OFChannelHandler h, OFPortStatus m)
+                    throws SwitchStateException {
+                handlePortStatusMessage(h, m, true);
+                h.dispatchMessage(m);
+            }
+
+            @Override
+            void processOFPacketIn(OFChannelHandler h, OFPacketIn m) {
+                h.dispatchMessage(m);
+            }
+
+            @Override
+            void processOFFlowRemoved(OFChannelHandler h,
+                    OFFlowRemoved m) {
+                h.dispatchMessage(m);
+            }
+
+            @Override
+            void processOFBarrierReply(OFChannelHandler h, OFBarrierReply m) {
+                h.dispatchMessage(m);
+            }
+
+        };
+
+        private final boolean handshakeComplete;
+        ChannelState(boolean handshakeComplete) {
+            this.handshakeComplete = handshakeComplete;
+        }
+
+        /**
+         * Is this a state in which the handshake has completed?
+         * @return true if the handshake is complete
+         */
+        public boolean isHandshakeComplete() {
+            return handshakeComplete;
+        }
+
+        /**
+         * Get a string specifying the switch connection, state, and
+         * message received. To be used as message for SwitchStateException
+         * or log messages
+         * @param h The channel handler (to get switch information_
+         * @param m The OFMessage that has just been received
+         * @param details A string giving more details about the exact nature
+         * of the problem.
+         * @return display string
+         */
+        // needs to be protected because enum members are actually subclasses
+        protected String getSwitchStateMessage(OFChannelHandler h,
+                OFMessage m,
+                String details) {
+            return String.format("Switch: [%s], State: [%s], received: [%s]"
+                    + ", details: %s",
+                    h.getSwitchInfoString(),
+                    this.toString(),
+                    m.getType().toString(),
+                    details);
+        }
+
+        /**
+         * We have an OFMessage we didn't expect given the current state and
+         * we want to treat this as an error.
+         * We currently throw an exception that will terminate the connection
+         * However, we could be more forgiving
+         * @param h the channel handler that received the message
+         * @param m the message
+         * @throws SwitchStateException
+         * @throws SwitchStateExeption we always through the execption
+         */
+        // needs to be protected because enum members are acutally subclasses
+        protected void illegalMessageReceived(OFChannelHandler h, OFMessage m)
+                throws SwitchStateException {
+            String msg = getSwitchStateMessage(h, m,
+                    "Switch should never send this message in the current state");
+            throw new SwitchStateException(msg);
+
+        }
+
+        /**
+         * We have an OFMessage we didn't expect given the current state and
+         * we want to ignore the message.
+         * @param h the channel handler the received the message
+         * @param m the message
+         */
+        protected void unhandledMessageReceived(OFChannelHandler h,
+                OFMessage m) {
+            if (log.isDebugEnabled()) {
+                String msg = getSwitchStateMessage(h, m,
+                        "Ignoring unexpected message");
+                log.debug(msg);
+            }
+        }
+
+        /**
+         * Log an OpenFlow error message from a switch.
+         * @param h The switch that sent the error
+         * @param error The error message
+         */
+        protected void logError(OFChannelHandler h, OFErrorMsg error) {
+            log.error("{} from switch {} in state {}",
+                    new Object[] {
+                    error,
+                    h.getSwitchInfoString(),
+                    this.toString()});
+        }
+
+        /**
+         * Log an OpenFlow error message from a switch and disconnect the
+         * channel.
+         *
+         * @param h the IO channel for this switch.
+         * @param error The error message
+         */
+        protected void logErrorDisconnect(OFChannelHandler h, OFErrorMsg error) {
+            logError(h, error);
+            h.channel.disconnect();
+        }
+
+        /**
+         * log an error message for a duplicate dpid and disconnect this channel.
+         * @param h the IO channel for this switch.
+         */
+        protected void disconnectDuplicate(OFChannelHandler h) {
+            log.error("Duplicated dpid or incompleted cleanup - "
+                    + "disconnecting channel {}", h.getSwitchInfoString());
+            h.duplicateDpidFound = Boolean.TRUE;
+            h.channel.disconnect();
+        }
+
+
+
+        /**
+         * Handles all pending port status messages before a switch is declared
+         * activated in MASTER or EQUAL role. Note that since this handling
+         * precedes the activation (and therefore notification to IOFSwitchListerners)
+         * the changes to ports will already be visible once the switch is
+         * activated. As a result, no notifications are sent out for these
+         * pending portStatus messages.
+         * @param h
+         * @throws SwitchStateException
+         */
+        protected void handlePendingPortStatusMessages(OFChannelHandler h) {
+            try {
+                handlePendingPortStatusMessages(h, 0);
+            } catch (SwitchStateException e) {
+                log.error(e.getMessage());
+            }
+        }
+
+        private void handlePendingPortStatusMessages(OFChannelHandler h, int index)
+                throws SwitchStateException {
+            if (h.sw == null) {
+                String msg = "State machine error: switch is null. Should never " +
+                        "happen";
+                throw new SwitchStateException(msg);
+            }
+            ArrayList<OFPortStatus> temp  = new ArrayList<OFPortStatus>();
+            for (OFPortStatus ps: h.pendingPortStatusMsg) {
+                temp.add(ps);
+                handlePortStatusMessage(h, ps, false);
+            }
+            temp.clear();
+            // expensive but ok - we don't expect too many port-status messages
+            // note that we cannot use clear(), because of the reasons below
+            h.pendingPortStatusMsg.removeAll(temp);
+            // the iterator above takes a snapshot of the list - so while we were
+            // dealing with the pending port-status messages, we could have received
+            // newer ones. Handle them recursively, but break the recursion after
+            // five steps to avoid an attack.
+            if (!h.pendingPortStatusMsg.isEmpty() && ++index < 5) {
+                handlePendingPortStatusMessages(h, index);
+            }
+        }
+
+        /**
+         * Handle a port status message.
+         *
+         * Handle a port status message by updating the port maps in the
+         * IOFSwitch instance and notifying Controller about the change so
+         * it can dispatch a switch update.
+         *
+         * @param h The OFChannelHhandler that received the message
+         * @param m The PortStatus message we received
+         * @param doNotify if true switch port changed events will be
+         * dispatched
+         * @throws SwitchStateException
+         *
+         */
+        protected void handlePortStatusMessage(OFChannelHandler h, OFPortStatus m,
+                boolean doNotify) throws SwitchStateException {
+            if (h.sw == null) {
+                String msg = getSwitchStateMessage(h, m,
+                        "State machine error: switch is null. Should never " +
+                        "happen");
+                throw new SwitchStateException(msg);
+            }
+
+            h.sw.handleMessage(m);
+        }
+
+
+        /**
+         * Process an OF message received on the channel and
+         * update state accordingly.
+         *
+         * The main "event" of the state machine. Process the received message,
+         * send follow up message if required and update state if required.
+         *
+         * Switches on the message type and calls more specific event handlers
+         * for each individual OF message type. If we receive a message that
+         * is supposed to be sent from a controller to a switch we throw
+         * a SwitchStateExeption.
+         *
+         * The more specific handlers can also throw SwitchStateExceptions
+         *
+         * @param h The OFChannelHandler that received the message
+         * @param m The message we received.
+         * @throws SwitchStateException
+         * @throws IOException
+         */
+        void processOFMessage(OFChannelHandler h, OFMessage m)
+                throws IOException, SwitchStateException {
+            switch(m.getType()) {
+            case HELLO:
+                processOFHello(h, (OFHello) m);
+                break;
+            case BARRIER_REPLY:
+                processOFBarrierReply(h, (OFBarrierReply) m);
+                break;
+            case ECHO_REPLY:
+                processOFEchoReply(h, (OFEchoReply) m);
+                break;
+            case ECHO_REQUEST:
+                processOFEchoRequest(h, (OFEchoRequest) m);
+                break;
+            case ERROR:
+                processOFError(h, (OFErrorMsg) m);
+                break;
+            case FEATURES_REPLY:
+                processOFFeaturesReply(h, (OFFeaturesReply) m);
+                break;
+            case FLOW_REMOVED:
+                processOFFlowRemoved(h, (OFFlowRemoved) m);
+                break;
+            case GET_CONFIG_REPLY:
+                processOFGetConfigReply(h, (OFGetConfigReply) m);
+                break;
+            case PACKET_IN:
+                processOFPacketIn(h, (OFPacketIn) m);
+                break;
+            case PORT_STATUS:
+                processOFPortStatus(h, (OFPortStatus) m);
+                break;
+            case QUEUE_GET_CONFIG_REPLY:
+                processOFQueueGetConfigReply(h, (OFQueueGetConfigReply) m);
+                break;
+            case STATS_REPLY: // multipart_reply in 1.3
+                processOFStatisticsReply(h, (OFStatsReply) m);
+                break;
+            case EXPERIMENTER:
+                processOFExperimenter(h, (OFExperimenter) m);
+                break;
+            case ROLE_REPLY:
+                processOFRoleReply(h, (OFRoleReply) m);
+                break;
+            case GET_ASYNC_REPLY:
+                processOFGetAsyncReply(h, (OFAsyncGetReply) m);
+                break;
+
+                // The following messages are sent to switches. The controller
+                // should never receive them
+            case SET_CONFIG:
+            case GET_CONFIG_REQUEST:
+            case PACKET_OUT:
+            case PORT_MOD:
+            case QUEUE_GET_CONFIG_REQUEST:
+            case BARRIER_REQUEST:
+            case STATS_REQUEST: // multipart request in 1.3
+            case FEATURES_REQUEST:
+            case FLOW_MOD:
+            case GROUP_MOD:
+            case TABLE_MOD:
+            case GET_ASYNC_REQUEST:
+            case SET_ASYNC:
+            case METER_MOD:
+            default:
+                illegalMessageReceived(h, m);
+                break;
+            }
+        }
+
+        /*-----------------------------------------------------------------
+         * Default implementation for message handlers in any state.
+         *
+         * Individual states must override these if they want a behavior
+         * that differs from the default.
+         *
+         * In general, these handlers simply ignore the message and do
+         * nothing.
+         *
+         * There are some exceptions though, since some messages really
+         * are handled the same way in every state (e.g., ECHO_REQUST) or
+         * that are only valid in a single state (e.g., HELLO, GET_CONFIG_REPLY
+         -----------------------------------------------------------------*/
+
+        void processOFHello(OFChannelHandler h, OFHello m)
+                throws IOException, SwitchStateException {
+            // we only expect hello in the WAIT_HELLO state
+            illegalMessageReceived(h, m);
+        }
+
+        void processOFBarrierReply(OFChannelHandler h, OFBarrierReply m)
+                throws IOException {
+            // Silently ignore.
+        }
+
+        void processOFEchoRequest(OFChannelHandler h, OFEchoRequest m)
+                throws IOException {
+            if (h.ofVersion == null) {
+                log.error("No OF version set for {}. Not sending Echo REPLY",
+                        h.channel.getRemoteAddress());
+                return;
+            }
+            OFFactory factory = (h.ofVersion == OFVersion.OF_13) ?
+                    h.controller.getOFMessageFactory13() : h.controller.getOFMessageFactory10();
+                    OFEchoReply reply = factory
+                            .buildEchoReply()
+                            .setXid(m.getXid())
+                            .setData(m.getData())
+                            .build();
+                    h.channel.write(Collections.singletonList(reply));
+        }
+
+        void processOFEchoReply(OFChannelHandler h, OFEchoReply m)
+                throws IOException {
+            // Do nothing with EchoReplies !!
+        }
+
+        // no default implementation for OFError
+        // every state must override it
+        abstract void processOFError(OFChannelHandler h, OFErrorMsg m)
+                throws IOException, SwitchStateException;
+
+
+        void processOFFeaturesReply(OFChannelHandler h, OFFeaturesReply  m)
+                throws IOException, SwitchStateException {
+            unhandledMessageReceived(h, m);
+        }
+
+        void processOFFlowRemoved(OFChannelHandler h, OFFlowRemoved m)
+                throws IOException {
+            unhandledMessageReceived(h, m);
+        }
+
+        void processOFGetConfigReply(OFChannelHandler h, OFGetConfigReply m)
+                throws IOException, SwitchStateException {
+            // we only expect config replies in the WAIT_CONFIG_REPLY state
+            illegalMessageReceived(h, m);
+        }
+
+        void processOFPacketIn(OFChannelHandler h, OFPacketIn m)
+                throws IOException {
+            unhandledMessageReceived(h, m);
+        }
+
+        // no default implementation. Every state needs to handle it.
+        abstract void processOFPortStatus(OFChannelHandler h, OFPortStatus m)
+                throws IOException, SwitchStateException;
+
+        void processOFQueueGetConfigReply(OFChannelHandler h,
+                OFQueueGetConfigReply m)
+                        throws IOException {
+            unhandledMessageReceived(h, m);
+        }
+
+        void processOFStatisticsReply(OFChannelHandler h, OFStatsReply m)
+                throws IOException, SwitchStateException {
+            unhandledMessageReceived(h, m);
+        }
+
+        void processOFExperimenter(OFChannelHandler h, OFExperimenter m)
+                throws IOException, SwitchStateException {
+            // TODO: it might make sense to parse the vendor message here
+            // into the known vendor messages we support and then call more
+            // specific event handlers
+            unhandledMessageReceived(h, m);
+        }
+
+        void processOFRoleReply(OFChannelHandler h, OFRoleReply m)
+                throws SwitchStateException, IOException {
+            unhandledMessageReceived(h, m);
+        }
+
+        void processOFGetAsyncReply(OFChannelHandler h,
+                OFAsyncGetReply m) {
+            unhandledMessageReceived(h, m);
+        }
+
+    }
+
+
+
+    //*************************
+    //  Channel handler methods
+    //*************************
+
+    @Override
+    public void channelConnected(ChannelHandlerContext ctx,
+            ChannelStateEvent e) throws Exception {
+        channel = e.getChannel();
+        log.info("New switch connection from {}",
+                channel.getRemoteAddress());
+        sendHandshakeHelloMessage();
+        setState(ChannelState.WAIT_HELLO);
+    }
+
+    @Override
+    public void channelDisconnected(ChannelHandlerContext ctx,
+            ChannelStateEvent e) throws Exception {
+        log.info("Switch disconnected callback for sw:{}. Cleaning up ...",
+                getSwitchInfoString());
+        if (thisdpid != 0) {
+            if (!duplicateDpidFound) {
+                // if the disconnected switch (on this ChannelHandler)
+                // was not one with a duplicate-dpid, it is safe to remove all
+                // state for it at the controller. Notice that if the disconnected
+                // switch was a duplicate-dpid, calling the method below would clear
+                // all state for the original switch (with the same dpid),
+                // which we obviously don't want.
+                sw.removeConnectedSwitch();
+            } else {
+                // A duplicate was disconnected on this ChannelHandler,
+                // this is the same switch reconnecting, but the original state was
+                // not cleaned up - XXX check liveness of original ChannelHandler
+                duplicateDpidFound = Boolean.FALSE;
+            }
+        } else {
+            log.warn("no dpid in channelHandler registered for "
+                    + "disconnected switch {}", getSwitchInfoString());
+        }
+    }
+
+    @Override
+    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e)
+            throws Exception {
+        if (e.getCause() instanceof ReadTimeoutException) {
+            // switch timeout
+            log.error("Disconnecting switch {} due to read timeout",
+                    getSwitchInfoString());
+            ctx.getChannel().close();
+        } else if (e.getCause() instanceof HandshakeTimeoutException) {
+            log.error("Disconnecting switch {}: failed to complete handshake",
+                    getSwitchInfoString());
+            ctx.getChannel().close();
+        } else if (e.getCause() instanceof ClosedChannelException) {
+            log.debug("Channel for sw {} already closed", getSwitchInfoString());
+        } else if (e.getCause() instanceof IOException) {
+            log.error("Disconnecting switch {} due to IO Error: {}",
+                    getSwitchInfoString(), e.getCause().getMessage());
+            if (log.isDebugEnabled()) {
+                // still print stack trace if debug is enabled
+                log.debug("StackTrace for previous Exception: ", e.getCause());
+            }
+            ctx.getChannel().close();
+        } else if (e.getCause() instanceof SwitchStateException) {
+            log.error("Disconnecting switch {} due to switch state error: {}",
+                    getSwitchInfoString(), e.getCause().getMessage());
+            if (log.isDebugEnabled()) {
+                // still print stack trace if debug is enabled
+                log.debug("StackTrace for previous Exception: ", e.getCause());
+            }
+            ctx.getChannel().close();
+        } else if (e.getCause() instanceof OFParseError) {
+            log.error("Disconnecting switch "
+                    + getSwitchInfoString() +
+                    " due to message parse failure",
+                    e.getCause());
+            ctx.getChannel().close();
+        } else if (e.getCause() instanceof RejectedExecutionException) {
+            log.warn("Could not process message: queue full");
+        } else {
+            log.error("Error while processing message from switch "
+                    + getSwitchInfoString()
+                    + "state " + this.state, e.getCause());
+            ctx.getChannel().close();
+        }
+    }
+
+    @Override
+    public String toString() {
+        return getSwitchInfoString();
+    }
+
+    @Override
+    public void channelIdle(ChannelHandlerContext ctx, IdleStateEvent e)
+            throws Exception {
+        OFFactory factory = (ofVersion == OFVersion.OF_13) ? factory13 : factory10;
+        OFMessage m = factory.buildEchoRequest().build();
+        log.info("Sending Echo Request on idle channel: {}",
+                e.getChannel().getPipeline().getLast().toString());
+        e.getChannel().write(Collections.singletonList(m));
+        // XXX S some problems here -- echo request has no transaction id, and
+        // echo reply is not correlated to the echo request.
+    }
+
+    @Override
+    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e)
+            throws Exception {
+        if (e.getMessage() instanceof List) {
+            @SuppressWarnings("unchecked")
+            List<OFMessage> msglist = (List<OFMessage>) e.getMessage();
+
+
+            for (OFMessage ofm : msglist) {
+                // Do the actual packet processing
+                state.processOFMessage(this, ofm);
+            }
+        } else {
+            state.processOFMessage(this, (OFMessage) e.getMessage());
+        }
+    }
+
+
+
+    //*************************
+    //  Channel utility methods
+    //*************************
+
+    /**
+     * Is this a state in which the handshake has completed?
+     * @return true if the handshake is complete
+     */
+    public boolean isHandshakeComplete() {
+        return this.state.isHandshakeComplete();
+    }
+
+    private void dispatchMessage(OFMessage m) {
+        sw.handleMessage(m);
+    }
+
+    /**
+     * Return a string describing this switch based on the already available
+     * information (DPID and/or remote socket).
+     * @return display string
+     */
+    private String getSwitchInfoString() {
+        if (sw != null) {
+            return sw.toString();
+        }
+        String channelString;
+        if (channel == null || channel.getRemoteAddress() == null) {
+            channelString = "?";
+        } else {
+            channelString = channel.getRemoteAddress().toString();
+        }
+        String dpidString;
+        if (featuresReply == null) {
+            dpidString = "?";
+        } else {
+            dpidString = featuresReply.getDatapathId().toString();
+        }
+        return String.format("[%s DPID[%s]]", channelString, dpidString);
+    }
+
+    /**
+     * Update the channels state. Only called from the state machine.
+     * TODO: enforce restricted state transitions
+     * @param state
+     */
+    private void setState(ChannelState state) {
+        this.state = state;
+    }
+
+    /**
+     * Send hello message to the switch using the handshake transactions ids.
+     * @throws IOException
+     */
+    private void sendHandshakeHelloMessage() throws IOException {
+        // The OF protocol requires us to start things off by sending the highest
+        // version of the protocol supported.
+
+        // bitmap represents OF1.0 (ofp_version=0x01) and OF1.3 (ofp_version=0x04)
+        // see Sec. 7.5.1 of the OF1.3.4 spec
+        U32 bitmap = U32.ofRaw(0x00000012);
+        OFHelloElem hem = factory13.buildHelloElemVersionbitmap()
+                .setBitmaps(Collections.singletonList(bitmap))
+                .build();
+        OFMessage.Builder mb = factory13.buildHello()
+                .setXid(this.handshakeTransactionIds--)
+                .setElements(Collections.singletonList(hem));
+        log.info("Sending OF_13 Hello to {}", channel.getRemoteAddress());
+        channel.write(Collections.singletonList(mb.build()));
+    }
+
+    /**
+     * Send featuresRequest msg to the switch using the handshake transactions ids.
+     * @throws IOException
+     */
+    private void sendHandshakeFeaturesRequestMessage() throws IOException {
+        OFFactory factory = (ofVersion == OFVersion.OF_13) ? factory13 : factory10;
+        OFMessage m = factory.buildFeaturesRequest()
+                .setXid(this.handshakeTransactionIds--)
+                .build();
+        channel.write(Collections.singletonList(m));
+    }
+
+    /**
+     * Send the configuration requests to tell the switch we want full
+     * packets.
+     * @throws IOException
+     */
+    private void sendHandshakeSetConfig() throws IOException {
+        OFFactory factory = (ofVersion == OFVersion.OF_13) ? factory13 : factory10;
+        //log.debug("Sending CONFIG_REQUEST to {}", channel.getRemoteAddress());
+        List<OFMessage> msglist = new ArrayList<OFMessage>(3);
+
+        // Ensure we receive the full packet via PacketIn
+        // FIXME: We don't set the reassembly flags.
+        OFSetConfig sc = factory
+                .buildSetConfig()
+                .setMissSendLen((short) 0xffff)
+                .setXid(this.handshakeTransactionIds--)
+                .build();
+        msglist.add(sc);
+
+        // Barrier
+        OFBarrierRequest br = factory
+                .buildBarrierRequest()
+                .setXid(this.handshakeTransactionIds--)
+                .build();
+        msglist.add(br);
+
+        // Verify (need barrier?)
+        OFGetConfigRequest gcr = factory
+                .buildGetConfigRequest()
+                .setXid(this.handshakeTransactionIds--)
+                .build();
+        msglist.add(gcr);
+        channel.write(msglist);
+    }
+
+    /**
+     * send a description state request.
+     * @throws IOException
+     */
+    private void sendHandshakeDescriptionStatsRequest() throws IOException {
+        // Get Description to set switch-specific flags
+        OFFactory factory = (ofVersion == OFVersion.OF_13) ? factory13 : factory10;
+        OFDescStatsRequest dreq = factory
+                .buildDescStatsRequest()
+                .setXid(handshakeTransactionIds--)
+                .build();
+        channel.write(Collections.singletonList(dreq));
+    }
+
+    private void sendHandshakeOFPortDescRequest() throws IOException {
+        // Get port description for 1.3 switch
+        OFPortDescStatsRequest preq = factory13
+                .buildPortDescStatsRequest()
+                .setXid(handshakeTransactionIds--)
+                .build();
+        channel.write(Collections.singletonList(preq));
+    }
+
+    ChannelState getStateForTesting() {
+        return state;
+    }
+
+}