Added BMv2 demo apps (onos1.6 cherry-pick)

Change-Id: I19484a826acce724c1fcd5b6e9910d724bda686f

+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright 2016-present Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <artifactId>onos-app-bmv2-demo</artifactId>
+        <groupId>org.onosproject</groupId>
+        <version>1.7.0-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>onos-app-bmv2-demo-common</artifactId>
+
+    <packaging>bundle</packaging>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.onosproject</groupId>
+            <artifactId>onos-bmv2-protocol-api</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+    </dependencies>
+</project>
\ No newline at end of file

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.bmv2.demo.app.common;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.app.ApplicationAdminService;
+import org.onosproject.bmv2.api.context.Bmv2DeviceContext;
+import org.onosproject.bmv2.api.service.Bmv2DeviceContextService;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Host;
+import org.onosproject.net.Port;
+import org.onosproject.net.device.DeviceEvent;
+import org.onosproject.net.device.DeviceListener;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.flow.DefaultFlowRule;
+import org.onosproject.net.flow.FlowRule;
+import org.onosproject.net.flow.FlowRuleOperations;
+import org.onosproject.net.flow.FlowRuleService;
+import org.onosproject.net.host.HostEvent;
+import org.onosproject.net.host.HostListener;
+import org.onosproject.net.host.HostService;
+import org.onosproject.net.topology.Topology;
+import org.onosproject.net.topology.TopologyEvent;
+import org.onosproject.net.topology.TopologyGraph;
+import org.onosproject.net.topology.TopologyListener;
+import org.onosproject.net.topology.TopologyService;
+import org.onosproject.net.topology.TopologyVertex;
+import org.slf4j.Logger;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.stream.Collectors.toSet;
+import static java.util.stream.Stream.concat;
+import static org.onlab.util.Tools.groupedThreads;
+import static org.onosproject.net.device.DeviceEvent.Type.*;
+import static org.onosproject.net.host.HostEvent.Type.HOST_ADDED;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Abstract implementation of an app providing fabric connectivity for a 2-stage Clos topology of BMv2 devices.
+ */
+@Component(immediate = true)
+public abstract class AbstractUpgradableFabricApp {
+
+    private static final Map<String, AbstractUpgradableFabricApp> APP_HANDLES = Maps.newConcurrentMap();
+
+    private static final int NUM_LEAFS = 3;
+    private static final int NUM_SPINES = 3;
+    private static final int FLOW_PRIORITY = 100;
+
+    private static final int CLEANUP_SLEEP = 1000;
+
+    protected final Logger log = getLogger(getClass());
+
+    private final TopologyListener topologyListener = new InternalTopologyListener();
+    private final DeviceListener deviceListener = new InternalDeviceListener();
+    private final HostListener hostListener = new InternalHostListener();
+
+    private final ExecutorService executorService = Executors
+            .newFixedThreadPool(8, groupedThreads("onos/bmv2-demo-app", "bmv2-app-task", log));
+
+    private final String appName;
+    private final String configurationName;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected TopologyService topologyService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected DeviceService deviceService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private HostService hostService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private FlowRuleService flowRuleService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private ApplicationAdminService appService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private CoreService coreService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private Bmv2DeviceContextService bmv2ContextService;
+
+    private boolean appActive = false;
+    private boolean appFreezed = false;
+
+    private boolean otherAppFound = false;
+    private AbstractUpgradableFabricApp otherApp;
+
+    private boolean flowRuleGenerated = false;
+    private ApplicationId appId;
+
+    private Bmv2DeviceContext bmv2Context;
+
+    private Set<DeviceId> leafSwitches;
+    private Set<DeviceId> spineSwitches;
+
+    private Map<DeviceId, List<FlowRule>> deviceFlowRules;
+    private Map<DeviceId, Boolean> rulesInstalled;
+
+    /**
+     * Creates a new Bmv2 Fabric Component.
+     *
+     * @param appName           app name
+     * @param configurationName a common name for the P4 program / BMv2 configuration used by this app
+     * @param context a BMv2 device context to be used on devices
+     */
+    protected AbstractUpgradableFabricApp(String appName, String configurationName, Bmv2DeviceContext context) {
+        this.appName = checkNotNull(appName);
+        this.configurationName = checkNotNull(configurationName);
+        this.bmv2Context = checkNotNull(context);
+    }
+
+    @Activate
+    public void activate() {
+        log.info("Starting...");
+
+        appActive = true;
+        appFreezed = false;
+
+        if (APP_HANDLES.size() > 0) {
+            if (APP_HANDLES.size() > 1) {
+                throw new IllegalStateException("Found more than 1 active app handles");
+            }
+            otherAppFound = true;
+            otherApp = APP_HANDLES.values().iterator().next();
+            log.info("Found other fabric app active, signaling to freeze to {}...", otherApp.appName);
+            otherApp.setAppFreezed(true);
+        }
+
+        APP_HANDLES.put(appName, this);
+
+        appId = coreService.registerApplication(appName);
+
+        topologyService.addListener(topologyListener);
+        deviceService.addListener(deviceListener);
+        hostService.addListener(hostListener);
+
+        bmv2ContextService.registerInterpreterClassLoader(bmv2Context.interpreter().getClass(),
+                                                          this.getClass().getClassLoader());
+
+        init();
+
+        log.info("STARTED", appId.id());
+    }
+
+    @Deactivate
+    public void deactivate() {
+        log.info("Stopping...");
+        try {
+            executorService.shutdown();
+            executorService.awaitTermination(5, TimeUnit.SECONDS);
+        } catch (InterruptedException e) {
+            List<Runnable> runningTasks = executorService.shutdownNow();
+            log.warn("Unable to stop the following tasks: {}", runningTasks);
+        }
+        deviceService.removeListener(deviceListener);
+        topologyService.removeListener(topologyListener);
+        hostService.removeListener(hostListener);
+        flowRuleService.removeFlowRulesById(appId);
+
+        appActive = false;
+        APP_HANDLES.remove(appName);
+
+        log.info("STOPPED");
+    }
+
+    private void init() {
+
+        // Reset any previous state
+        synchronized (this) {
+            flowRuleGenerated = Boolean.FALSE;
+            leafSwitches = Sets.newHashSet();
+            spineSwitches = Sets.newHashSet();
+            deviceFlowRules = Maps.newConcurrentMap();
+            rulesInstalled = Maps.newConcurrentMap();
+        }
+
+        // Start flow rules generator...
+        spawnTask(() -> generateFlowRules(topologyService.currentTopology(), Sets.newHashSet(hostService.getHosts())));
+    }
+
+    private void setAppFreezed(boolean appFreezed) {
+        this.appFreezed = appFreezed;
+        if (appFreezed) {
+            log.info("Freezing...");
+        } else {
+            log.info("Unfreezing...!");
+        }
+    }
+
+    /**
+     * Perform device initialization. Returns true if the operation was successful, false otherwise.
+     *
+     * @param deviceId a device id
+     * @return a boolean value
+     */
+    public abstract boolean initDevice(DeviceId deviceId);
+
+    /**
+     * Generates a list of flow rules for the given leaf switch, source host, destination hosts, spine switches and
+     * topology.
+     *
+     * @param leaf     a leaf device id
+     * @param srcHost  a source host
+     * @param dstHosts a collection of destination hosts
+     * @param spines   a collection of spine device IDs
+     * @param topology a topology
+     * @return a list of flow rules
+     * @throws FlowRuleGeneratorException if flow rules cannot be generated
+     */
+    public abstract List<FlowRule> generateLeafRules(DeviceId leaf, Host srcHost, Collection<Host> dstHosts,
+                                                     Collection<DeviceId> spines, Topology topology)
+            throws FlowRuleGeneratorException;
+
+    /**
+     * Generates a list of flow rules for the given spine switch, destination hosts and topology.
+     *
+     * @param deviceId a spine device id
+     * @param dstHosts a collection of destination hosts
+     * @param topology a topology
+     * @return a list of flow rules
+     * @throws FlowRuleGeneratorException if flow rules cannot be generated
+     */
+    public abstract List<FlowRule> generateSpineRules(DeviceId deviceId, Collection<Host> dstHosts, Topology topology)
+            throws FlowRuleGeneratorException;
+
+    private void deployRoutine() {
+        if (otherAppFound && otherApp.appActive) {
+            log.info("Starting update routine...");
+            updateRoutine();
+            appService.deactivate(otherApp.appId);
+        } else {
+            Stream.concat(leafSwitches.stream(), spineSwitches.stream())
+                    .map(deviceService::getDevice)
+                    .forEach(device -> spawnTask(() -> deployDevice(device)));
+        }
+    }
+
+    private void updateRoutine() {
+        Stream.concat(leafSwitches.stream(), spineSwitches.stream())
+                .forEach(did -> spawnTask(() -> {
+                    cleanUpDevice(did);
+                    try {
+                        Thread.sleep(CLEANUP_SLEEP);
+                    } catch (InterruptedException e) {
+                        log.warn("Cleanup sleep interrupted!");
+                        Thread.interrupted();
+                    }
+                    deployDevice(deviceService.getDevice(did));
+                }));
+    }
+
+    private void cleanUpDevice(DeviceId deviceId) {
+        List<FlowRule> flowRulesToRemove = Lists.newArrayList();
+        flowRuleService.getFlowEntries(deviceId).forEach(fe -> {
+            if (fe.appId() == otherApp.appId.id()) {
+                flowRulesToRemove.add(fe);
+            }
+        });
+        if (flowRulesToRemove.size() > 0) {
+            log.info("Cleaning {} old flow rules from {}...", flowRulesToRemove.size(), deviceId);
+            removeFlowRules(flowRulesToRemove);
+        }
+    }
+
+    /**
+     * Executes a device deploy.
+     *
+     * @param device a device
+     */
+    public void deployDevice(Device device) {
+        // Serialize executions per device ID using a concurrent map.
+        rulesInstalled.compute(device.id(), (did, deployed) -> {
+            Bmv2DeviceContext deviceContext = bmv2ContextService.getContext(device.id());
+            if (deviceContext == null) {
+                log.error("Unable to get context for device {}", device.id());
+                return deployed;
+            } else if (!deviceContext.equals(bmv2Context)) {
+                log.info("Swapping configuration to {} on device {}...", configurationName, device.id());
+                bmv2ContextService.triggerConfigurationSwap(device.id(), bmv2Context);
+                return deployed;
+            }
+
+            List<FlowRule> rules = deviceFlowRules.get(device.id());
+            if (initDevice(device.id())) {
+                if (deployed == null && rules != null && rules.size() > 0) {
+                    log.info("Installing rules for {}...", did);
+                    installFlowRules(rules);
+                    return true;
+                }
+            } else {
+                log.warn("Filed to initialize device {}", device.id());
+                if (deployed != null && rules != null && rules.size() > 0) {
+                    log.info("Removing rules for {}...", did);
+                    removeFlowRules(rules);
+                    return null;
+                }
+            }
+
+            return deployed;
+        });
+    }
+
+    private void spawnTask(Runnable task) {
+        executorService.execute(task);
+    }
+
+
+    private void installFlowRules(Collection<FlowRule> rules) {
+        FlowRuleOperations.Builder opsBuilder = FlowRuleOperations.builder();
+        rules.forEach(opsBuilder::add);
+        flowRuleService.apply(opsBuilder.build());
+    }
+
+    private void removeFlowRules(Collection<FlowRule> rules) {
+        FlowRuleOperations.Builder opsBuilder = FlowRuleOperations.builder();
+        rules.forEach(opsBuilder::remove);
+        flowRuleService.apply(opsBuilder.build());
+    }
+
+    /**
+     * Generates the flow rules to provide host-to-host connectivity for the given topology and hosts.
+     *
+     * @param topo  a topology
+     * @param hosts a collection of hosts
+     */
+    private synchronized void generateFlowRules(Topology topo, Collection<Host> hosts) {
+
+        if (flowRuleGenerated) {
+            log.debug("Flow rules have been already generated, aborting...");
+            return;
+        }
+
+        log.debug("Starting flow rules generator...");
+
+        TopologyGraph graph = topologyService.getGraph(topo);
+        Set<DeviceId> spines = Sets.newHashSet();
+        Set<DeviceId> leafs = Sets.newHashSet();
+        graph.getVertexes().stream()
+                .map(TopologyVertex::deviceId)
+                .forEach(did -> (isSpine(did, topo) ? spines : leafs).add(did));
+
+        if (spines.size() != NUM_SPINES || leafs.size() != NUM_LEAFS) {
+            log.info("Invalid leaf/spine switches count, aborting... > leafCount={}, spineCount={}",
+                     spines.size(), leafs.size());
+            return;
+        }
+
+        for (DeviceId did : spines) {
+            int portCount = deviceService.getPorts(did).size();
+            // Expected port count: num leafs + 1 redundant leaf link
+            if (portCount != (NUM_LEAFS + 1)) {
+                log.info("Invalid port count for spine, aborting... > deviceId={}, portCount={}", did, portCount);
+                return;
+            }
+        }
+        for (DeviceId did : leafs) {
+            int portCount = deviceService.getPorts(did).size();
+            // Expected port count: num spines + host port + 1 redundant spine link
+            if (portCount != (NUM_SPINES + 2)) {
+                log.info("Invalid port count for leaf, aborting... > deviceId={}, portCount={}", did, portCount);
+                return;
+            }
+        }
+
+        // Check hosts, number and exactly one per leaf
+        Map<DeviceId, Host> hostMap = Maps.newHashMap();
+        hosts.forEach(h -> hostMap.put(h.location().deviceId(), h));
+        if (hosts.size() != NUM_LEAFS || !leafs.equals(hostMap.keySet())) {
+            log.info("Wrong host configuration, aborting... > hostCount={}, hostMapz={}", hosts.size(), hostMap);
+            return;
+        }
+
+        List<FlowRule> newFlowRules = Lists.newArrayList();
+
+        try {
+            for (DeviceId deviceId : leafs) {
+                Host srcHost = hostMap.get(deviceId);
+                Set<Host> dstHosts = hosts.stream().filter(h -> h != srcHost).collect(toSet());
+                newFlowRules.addAll(generateLeafRules(deviceId, srcHost, dstHosts, spines, topo));
+            }
+            for (DeviceId deviceId : spines) {
+                newFlowRules.addAll(generateSpineRules(deviceId, hosts, topo));
+            }
+        } catch (FlowRuleGeneratorException e) {
+            log.warn("Exception while executing flow rule generator: ", e.toString());
+            return;
+        }
+
+        if (newFlowRules.size() == 0) {
+            // Something went wrong
+            log.error("0 flow rules generated, BUG?");
+            return;
+        }
+
+        // All good!
+        // Divide flow rules per device id...
+        ImmutableMap.Builder<DeviceId, List<FlowRule>> mapBuilder = ImmutableMap.builder();
+        concat(spines.stream(), leafs.stream())
+                .map(deviceId -> ImmutableList.copyOf(newFlowRules
+                        .stream()
+                        .filter(fr -> fr.deviceId().equals(deviceId))
+                        .iterator()))
+                .forEach(frs -> mapBuilder.put(frs.get(0).deviceId(), frs));
+        this.deviceFlowRules = mapBuilder.build();
+
+        this.leafSwitches = ImmutableSet.copyOf(leafs);
+        this.spineSwitches = ImmutableSet.copyOf(spines);
+
+        // Avoid other executions to modify the generated flow rules.
+        flowRuleGenerated = true;
+
+        log.info("DONE! Generated {} flow rules for {} devices...", newFlowRules.size(), spines.size() + leafs.size());
+
+        // Deploy configuration.
+        spawnTask(this::deployRoutine);
+    }
+
+    /**
+     * Returns a new, pre-configured flow rule builder.
+     *
+     * @param did       a device id
+     * @param tableName a table name
+     * @return a new flow rule builder
+     */
+    protected FlowRule.Builder flowRuleBuilder(DeviceId did, String tableName) throws FlowRuleGeneratorException {
+        Map<String, Integer> tableMap = bmv2Context.interpreter().tableIdMap().inverse();
+        if (tableMap.get(tableName) == null) {
+            throw new FlowRuleGeneratorException("Unknown table " + tableName);
+        }
+        return DefaultFlowRule.builder()
+                .forDevice(did)
+                .forTable(tableMap.get(tableName))
+                .fromApp(appId)
+                .withPriority(FLOW_PRIORITY)
+                .makePermanent();
+    }
+
+    private List<Port> getHostPorts(DeviceId deviceId, Topology topology) {
+        // Get all non-fabric ports.
+        return deviceService
+                .getPorts(deviceId)
+                .stream()
+                .filter(p -> !isFabricPort(p, topology))
+                .collect(Collectors.toList());
+    }
+
+    private boolean isSpine(DeviceId deviceId, Topology topology) {
+        // True if all ports are fabric.
+        return getHostPorts(deviceId, topology).size() == 0;
+    }
+
+    protected boolean isFabricPort(Port port, Topology topology) {
+        // True if the port connects this device to another infrastructure device.
+        return topologyService.isInfrastructure(topology, new ConnectPoint(port.element().id(), port.number()));
+    }
+
+    /**
+     * A listener of topology events that executes a flow rule generation task each time a device is added.
+     */
+    private class InternalTopologyListener implements TopologyListener {
+
+        @Override
+        public void event(TopologyEvent event) {
+            spawnTask(() -> generateFlowRules(event.subject(), Sets.newHashSet(hostService.getHosts())));
+        }
+
+        @Override
+        public boolean isRelevant(TopologyEvent event) {
+            return !appFreezed &&
+                    // If at least one reason is of type DEVICE_ADDED.
+                    event.reasons().stream().
+                            filter(r -> r instanceof DeviceEvent)
+                            .filter(r -> ((DeviceEvent) r).type() == DEVICE_ADDED)
+                            .findAny()
+                            .isPresent();
+        }
+    }
+
+    /**
+     * A listener of device events that executes a device deploy task each time a device is added, updated or
+     * re-connects.
+     */
+    private class InternalDeviceListener implements DeviceListener {
+        @Override
+        public void event(DeviceEvent event) {
+            spawnTask(() -> deployDevice(event.subject()));
+        }
+
+        @Override
+        public boolean isRelevant(DeviceEvent event) {
+            return !appFreezed &&
+                    (event.type() == DEVICE_ADDED ||
+                            event.type() == DEVICE_UPDATED ||
+                            (event.type() == DEVICE_AVAILABILITY_CHANGED &&
+                                    deviceService.isAvailable(event.subject().id())));
+        }
+    }
+
+    /**
+     * A listener of host events that generates flow rules each time a new host is added.
+     */
+    private class InternalHostListener implements HostListener {
+        @Override
+        public void event(HostEvent event) {
+            spawnTask(() -> generateFlowRules(topologyService.currentTopology(),
+                                              Sets.newHashSet(hostService.getHosts())));
+        }
+
+        @Override
+        public boolean isRelevant(HostEvent event) {
+            return !appFreezed && event.type() == HOST_ADDED;
+        }
+    }
+
+    /**
+     * An exception occurred while generating flow rules for this fabric.
+     */
+    public class FlowRuleGeneratorException extends Exception {
+
+        public FlowRuleGeneratorException() {
+        }
+
+        public FlowRuleGeneratorException(String msg) {
+            super(msg);
+        }
+
+        public FlowRuleGeneratorException(Exception cause) {
+            super(cause);
+        }
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Bmv2 demo app common classes.
+ */
+package org.onosproject.bmv2.demo.app.common;
\ No newline at end of file

+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+
+<!--
+  ~ Copyright 2016-present Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<features xmlns="http://karaf.apache.org/xmlns/features/v1.2.0" name="${project.artifactId}-${project.version}">
+    <feature name="${project.artifactId}" version="${project.version}"
+             description="${project.description}">
+        <bundle>mvn:${project.groupId}/${project.artifactId}/${project.version}</bundle>
+        <bundle>mvn:${project.groupId}/onos-app-bmv2-demo-common/${project.version}</bundle>
+    </feature>
+</features>

+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright 2016-present Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <artifactId>onos-app-bmv2-demo</artifactId>
+        <groupId>org.onosproject</groupId>
+        <version>1.7.0-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>onos-app-bmv2-demo-ecmp</artifactId>
+
+    <packaging>bundle</packaging>
+
+    <properties>
+        <onos.app.name>org.onosproject.bmv2-ecmp-fabric</onos.app.name>
+        <onos.app.title>P4/BMv2 Demo Fabric App v1 (ECMP)</onos.app.title>
+        <onos.app.category>Traffic Steering</onos.app.category>
+        <onos.app.url>http://onosproject.org</onos.app.url>
+        <onos.app.readme>P4/BMv2 demo application with ECMP support for a 2-stage clos fabric topology</onos.app.readme>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.onosproject</groupId>
+            <artifactId>onos-app-bmv2-demo-common</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+    </dependencies>
+
+</project>
\ No newline at end of file

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.bmv2.demo.app.ecmp;
+
+import com.eclipsesource.json.Json;
+import com.eclipsesource.json.JsonObject;
+import com.google.common.collect.Lists;
+import org.apache.commons.lang3.tuple.Pair;
+import org.apache.felix.scr.annotations.Component;
+import org.onosproject.bmv2.api.context.Bmv2Configuration;
+import org.onosproject.bmv2.api.context.Bmv2DefaultConfiguration;
+import org.onosproject.bmv2.api.context.Bmv2DeviceContext;
+import org.onosproject.bmv2.demo.app.common.AbstractUpgradableFabricApp;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Host;
+import org.onosproject.net.Path;
+import org.onosproject.net.Port;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.flow.DefaultTrafficSelector;
+import org.onosproject.net.flow.DefaultTrafficTreatment;
+import org.onosproject.net.flow.FlowRule;
+import org.onosproject.net.flow.TrafficTreatment;
+import org.onosproject.net.flow.criteria.ExtensionSelector;
+import org.onosproject.net.flow.instructions.ExtensionTreatment;
+import org.onosproject.net.topology.DefaultTopologyVertex;
+import org.onosproject.net.topology.Topology;
+import org.onosproject.net.topology.TopologyGraph;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static java.util.stream.Collectors.toSet;
+import static org.onlab.packet.EthType.EtherType.IPV4;
+import static org.onosproject.bmv2.demo.app.ecmp.EcmpGroupTreatmentBuilder.groupIdOf;
+import static org.onosproject.bmv2.demo.app.ecmp.EcmpInterpreter.ECMP_GROUP_TABLE;
+import static org.onosproject.bmv2.demo.app.ecmp.EcmpInterpreter.TABLE0;
+
+/**
+ * Implementation of an upgradable fabric app for the ECMP configuration.
+ */
+@Component(immediate = true)
+public class EcmpFabricApp extends AbstractUpgradableFabricApp {
+
+    private static final String APP_NAME = "org.onosproject.bmv2-ecmp-fabric";
+    private static final String MODEL_NAME = "ECMP";
+    private static final String JSON_CONFIG_PATH = "/ecmp.json";
+
+    private static final Bmv2Configuration ECMP_CONFIGURATION = loadConfiguration();
+    private static final EcmpInterpreter ECMP_INTERPRETER = new EcmpInterpreter();
+    protected static final Bmv2DeviceContext ECMP_CONTEXT = new Bmv2DeviceContext(ECMP_CONFIGURATION, ECMP_INTERPRETER);
+
+    public EcmpFabricApp() {
+        super(APP_NAME, MODEL_NAME, ECMP_CONTEXT);
+    }
+
+    @Override
+    public boolean initDevice(DeviceId deviceId) {
+        // Nothing to do.
+        return true;
+    }
+
+    @Override
+    public List<FlowRule> generateLeafRules(DeviceId leaf, Host srcHost, Collection<Host> dstHosts,
+                                            Collection<DeviceId> availableSpines, Topology topo)
+            throws FlowRuleGeneratorException {
+
+        // Get ports which connect this leaf switch to hosts.
+        Set<PortNumber> hostPorts = deviceService.getPorts(leaf)
+                .stream()
+                .filter(port -> !isFabricPort(port, topo))
+                .map(Port::number)
+                .collect(Collectors.toSet());
+
+        // Get ports which connect this leaf to the given available spines.
+        TopologyGraph graph = topologyService.getGraph(topo);
+        Set<PortNumber> fabricPorts = graph.getEdgesFrom(new DefaultTopologyVertex(leaf))
+                .stream()
+                .filter(e -> availableSpines.contains(e.dst().deviceId()))
+                .map(e -> e.link().src().port())
+                .collect(Collectors.toSet());
+
+        if (hostPorts.size() != 1 || fabricPorts.size() == 0) {
+            log.error("Leaf switch has invalid port configuration: hostPorts={}, fabricPorts={}",
+                      hostPorts.size(), fabricPorts.size());
+            throw new FlowRuleGeneratorException();
+        }
+        PortNumber hostPort = hostPorts.iterator().next();
+
+        List<FlowRule> rules = Lists.newArrayList();
+
+        TrafficTreatment treatment;
+        if (fabricPorts.size() > 1) {
+            // Do ECMP.
+            Pair<ExtensionTreatment, List<FlowRule>> result = provisionEcmpTreatment(leaf, fabricPorts);
+            rules.addAll(result.getRight());
+            ExtensionTreatment extTreatment = result.getLeft();
+            treatment = DefaultTrafficTreatment.builder().extension(extTreatment, leaf).build();
+        } else {
+            // Output on port.
+            PortNumber outPort = fabricPorts.iterator().next();
+            treatment = DefaultTrafficTreatment.builder().setOutput(outPort).build();
+        }
+
+        // From srHost to dstHosts.
+        for (Host dstHost : dstHosts) {
+            FlowRule rule = flowRuleBuilder(leaf, TABLE0)
+                    .withSelector(
+                            DefaultTrafficSelector.builder()
+                                    .matchInPort(hostPort)
+                                    .matchEthType(IPV4.ethType().toShort())
+                                    .matchEthSrc(srcHost.mac())
+                                    .matchEthDst(dstHost.mac())
+                                    .build())
+                    .withTreatment(treatment)
+                    .build();
+            rules.add(rule);
+        }
+
+        // From fabric ports to this leaf host.
+        for (PortNumber port : fabricPorts) {
+            FlowRule rule = flowRuleBuilder(leaf, TABLE0)
+                    .withSelector(
+                            DefaultTrafficSelector.builder()
+                                    .matchInPort(port)
+                                    .matchEthType(IPV4.ethType().toShort())
+                                    .matchEthDst(srcHost.mac())
+                                    .build())
+                    .withTreatment(
+                            DefaultTrafficTreatment.builder()
+                                    .setOutput(hostPort)
+                                    .build())
+                    .build();
+            rules.add(rule);
+        }
+
+        return rules;
+    }
+
+    @Override
+    public List<FlowRule> generateSpineRules(DeviceId deviceId, Collection<Host> dstHosts, Topology topo)
+            throws FlowRuleGeneratorException {
+
+        List<FlowRule> rules = Lists.newArrayList();
+
+        // for each host
+        for (Host dstHost : dstHosts) {
+
+            Set<Path> paths = topologyService.getPaths(topo, deviceId, dstHost.location().deviceId());
+
+            if (paths.size() == 0) {
+                log.warn("Can't find any path between spine {} and host {}", deviceId, dstHost);
+                throw new FlowRuleGeneratorException();
+            }
+
+            TrafficTreatment treatment;
+
+            if (paths.size() == 1) {
+                // Only one path, do output on port.
+                PortNumber port = paths.iterator().next().src().port();
+                treatment = DefaultTrafficTreatment.builder().setOutput(port).build();
+            } else {
+                // Multiple paths, do ECMP.
+                Set<PortNumber> portNumbers = paths.stream().map(p -> p.src().port()).collect(toSet());
+                Pair<ExtensionTreatment, List<FlowRule>> result = provisionEcmpTreatment(deviceId, portNumbers);
+                rules.addAll(result.getRight());
+                treatment = DefaultTrafficTreatment.builder().extension(result.getLeft(), deviceId).build();
+            }
+
+            FlowRule rule = flowRuleBuilder(deviceId, TABLE0)
+                    .withSelector(
+                            DefaultTrafficSelector.builder()
+                                    .matchEthType(IPV4.ethType().toShort())
+                                    .matchEthDst(dstHost.mac())
+                                    .build())
+                    .withTreatment(treatment)
+                    .build();
+
+            rules.add(rule);
+        }
+
+        return rules;
+    }
+
+    private Pair<ExtensionTreatment, List<FlowRule>> provisionEcmpTreatment(DeviceId deviceId,
+                                                                            Set<PortNumber> fabricPorts)
+            throws FlowRuleGeneratorException {
+
+        // Install ECMP group table entries that map from hash values to actual fabric ports...
+        int groupId = groupIdOf(deviceId, fabricPorts);
+        int groupSize = fabricPorts.size();
+        Iterator<PortNumber> portIterator = fabricPorts.iterator();
+        List<FlowRule> rules = Lists.newArrayList();
+        for (short i = 0; i < groupSize; i++) {
+            ExtensionSelector extSelector = new EcmpGroupTableSelectorBuilder()
+                    .withGroupId(groupId)
+                    .withSelector(i)
+                    .build();
+            FlowRule rule = flowRuleBuilder(deviceId, ECMP_GROUP_TABLE)
+                    .withSelector(
+                            DefaultTrafficSelector.builder()
+                                    .extension(extSelector, deviceId)
+                                    .build())
+                    .withTreatment(
+                            DefaultTrafficTreatment.builder()
+                                    .setOutput(portIterator.next())
+                                    .build())
+                    .build();
+            rules.add(rule);
+        }
+
+        ExtensionTreatment extTreatment = new EcmpGroupTreatmentBuilder()
+                .withGroupId(groupId)
+                .withGroupSize(groupSize)
+                .build();
+
+        return Pair.of(extTreatment, rules);
+    }
+
+    private static Bmv2Configuration loadConfiguration() {
+        try {
+            JsonObject json = Json.parse(new BufferedReader(new InputStreamReader(
+                    EcmpFabricApp.class.getResourceAsStream(JSON_CONFIG_PATH)))).asObject();
+            return Bmv2DefaultConfiguration.parse(json);
+        } catch (IOException e) {
+            throw new RuntimeException("Unable to load configuration", e);
+        }
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.bmv2.demo.app.ecmp;
+
+import com.google.common.collect.ImmutableMap;
+import org.onlab.util.ImmutableByteSequence;
+import org.onosproject.bmv2.api.context.Bmv2HeaderTypeModel;
+import org.onosproject.bmv2.api.runtime.Bmv2ExactMatchParam;
+import org.onosproject.bmv2.api.runtime.Bmv2ExtensionSelector;
+import org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils;
+import org.onosproject.net.flow.criteria.ExtensionSelector;
+
+import static org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils.fitByteSequence;
+import static org.onosproject.bmv2.demo.app.ecmp.EcmpFabricApp.ECMP_CONTEXT;
+import static org.onosproject.bmv2.demo.app.ecmp.EcmpInterpreter.*;
+
+/**
+ * Builder of ECMP group table extension selector.
+ */
+public class EcmpGroupTableSelectorBuilder {
+
+    private int groupId;
+    private int selector;
+
+    /**
+     * Sets the ECMP group ID.
+     *
+     * @param groupId an integer value
+     * @return this
+     */
+    public EcmpGroupTableSelectorBuilder withGroupId(int groupId) {
+        this.groupId = groupId;
+        return this;
+    }
+
+    /**
+     * Sets the ECMP selector.
+     *
+     * @param selector an integer value
+     * @return this
+     */
+    public EcmpGroupTableSelectorBuilder withSelector(int selector) {
+        this.selector = selector;
+        return this;
+    }
+
+    /**
+     * Returns a new extension selector.
+     *
+     * @return an extension selector
+     */
+    public ExtensionSelector build() {
+        Bmv2HeaderTypeModel headerTypeModel = ECMP_CONTEXT.configuration().headerType(ECMP_METADATA_T);
+        int groupIdBitWidth = headerTypeModel.field(GROUP_ID).bitWidth();
+        int selectorBitWidth = headerTypeModel.field(SELECTOR).bitWidth();
+
+        try {
+            ImmutableByteSequence groupIdBs = fitByteSequence(ImmutableByteSequence.copyFrom(groupId),
+                                                              groupIdBitWidth);
+            ImmutableByteSequence selectorBs = fitByteSequence(ImmutableByteSequence.copyFrom(selector),
+                                                               selectorBitWidth);
+
+            Bmv2ExactMatchParam groupIdMatch = new Bmv2ExactMatchParam(groupIdBs);
+            Bmv2ExactMatchParam hashMatch = new Bmv2ExactMatchParam(selectorBs);
+
+            return new Bmv2ExtensionSelector(ImmutableMap.of(
+                    ECMP_METADATA + "." + GROUP_ID, groupIdMatch,
+                    ECMP_METADATA + "." + SELECTOR, hashMatch));
+
+        } catch (Bmv2TranslatorUtils.ByteSequenceFitException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.bmv2.demo.app.ecmp;
+
+import com.google.common.collect.Maps;
+import org.onlab.util.ImmutableByteSequence;
+import org.onosproject.bmv2.api.context.Bmv2ActionModel;
+import org.onosproject.bmv2.api.runtime.Bmv2Action;
+import org.onosproject.bmv2.api.runtime.Bmv2ExtensionTreatment;
+import org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.flow.instructions.ExtensionTreatment;
+
+import java.util.Map;
+import java.util.Set;
+
+import static org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils.fitByteSequence;
+import static org.onosproject.bmv2.demo.app.ecmp.EcmpFabricApp.ECMP_CONTEXT;
+import static org.onosproject.bmv2.demo.app.ecmp.EcmpInterpreter.*;
+
+/**
+ * Builder of ECMP extension treatments.
+ */
+public class EcmpGroupTreatmentBuilder {
+
+    private static final Map<DeviceId, Map<Set<PortNumber>, Short>> DEVICE_GROUP_ID_MAP = Maps.newHashMap();
+    private int groupId;
+    private int groupSize;
+
+    /**
+     * Sets the group ID.
+     *
+     * @param groupId an integer value
+     * @return this
+     */
+    public EcmpGroupTreatmentBuilder withGroupId(int groupId) {
+        this.groupId = groupId;
+        return this;
+    }
+
+    /**
+     * Sets the group size.
+     *
+     * @param groupSize an integer value
+     * @return this
+     */
+    public EcmpGroupTreatmentBuilder withGroupSize(int groupSize) {
+        this.groupSize = groupSize;
+        return this;
+    }
+
+    /**
+     * Returns a new extension treatment.
+     *
+     * @return an extension treatment
+     */
+    public ExtensionTreatment build() {
+        Bmv2ActionModel actionModel = ECMP_CONTEXT.configuration().action(ECMP_GROUP);
+        int groupIdBitWidth = actionModel.runtimeData(GROUP_ID).bitWidth();
+        int groupSizeBitWidth = actionModel.runtimeData(GROUP_SIZE).bitWidth();
+
+        try {
+            ImmutableByteSequence groupIdBs = fitByteSequence(ImmutableByteSequence.copyFrom(groupId), groupIdBitWidth);
+            ImmutableByteSequence groupSizeBs = fitByteSequence(ImmutableByteSequence.copyFrom(groupSize),
+                                                                groupSizeBitWidth);
+
+            return new Bmv2ExtensionTreatment(Bmv2Action.builder()
+                                                      .withName(ECMP_GROUP)
+                                                      .addParameter(groupIdBs)
+                                                      .addParameter(groupSizeBs)
+                                                      .build());
+
+        } catch (Bmv2TranslatorUtils.ByteSequenceFitException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Returns a group ID for the given device and set of ports.
+     *
+     * @param deviceId a device ID
+     * @param ports a set of ports
+     * @return an integer value
+     */
+    public static int groupIdOf(DeviceId deviceId, Set<PortNumber> ports) {
+        DEVICE_GROUP_ID_MAP.putIfAbsent(deviceId, Maps.newHashMap());
+        // Counts the number of unique portNumber sets for each deviceId.
+        // Each distinct set of portNumbers will have a unique ID.
+        return DEVICE_GROUP_ID_MAP.get(deviceId).computeIfAbsent(ports, (pp) ->
+                (short) (DEVICE_GROUP_ID_MAP.get(deviceId).size() + 1));
+    }
+}

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.bmv2.demo.app.ecmp;
+
+import com.google.common.collect.ImmutableBiMap;
+import org.onlab.util.ImmutableByteSequence;
+import org.onosproject.bmv2.api.context.Bmv2Configuration;
+import org.onosproject.bmv2.api.context.Bmv2Interpreter;
+import org.onosproject.bmv2.api.context.Bmv2InterpreterException;
+import org.onosproject.bmv2.api.runtime.Bmv2Action;
+import org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.flow.TrafficTreatment;
+import org.onosproject.net.flow.criteria.Criterion;
+import org.onosproject.net.flow.instructions.Instruction;
+
+import static org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils.fitByteSequence;
+import static org.onosproject.net.PortNumber.CONTROLLER;
+import static org.onosproject.net.flow.instructions.Instructions.OutputInstruction;
+
+/**
+ * Implementation of a BMv2 interpreter for the ecmp.json configuration.
+ */
+public class EcmpInterpreter implements Bmv2Interpreter {
+
+    protected static final String ECMP_METADATA_T = "ecmp_metadata_t";
+    protected static final String ECMP_METADATA = "ecmp_metadata";
+    protected static final String SELECTOR = "selector";
+    protected static final String GROUP_ID = "groupId";
+    protected static final String GROUP_SIZE = "groupSize";
+    protected static final String ECMP_GROUP = "ecmp_group";
+    protected static final String ECMP_GROUP_TABLE = "ecmp_group_table";
+    protected static final String TABLE0 = "table0";
+    protected static final String SEND_TO_CPU = "send_to_cpu";
+    protected static final String DROP = "_drop";
+    protected static final String SET_EGRESS_PORT = "set_egress_port";
+    protected static final String PORT = "port";
+
+    private static final ImmutableBiMap<Criterion.Type, String> CRITERION_TYPE_MAP = ImmutableBiMap.of(
+            Criterion.Type.IN_PORT, "standard_metadata.ingress_port",
+            Criterion.Type.ETH_DST, "ethernet.dstAddr",
+            Criterion.Type.ETH_SRC, "ethernet.srcAddr",
+            Criterion.Type.ETH_TYPE, "ethernet.etherType");
+
+    private static final ImmutableBiMap<Integer, String> TABLE_ID_MAP = ImmutableBiMap.of(
+            0, TABLE0,
+            1, ECMP_GROUP_TABLE);
+
+    @Override
+    public ImmutableBiMap<Integer, String> tableIdMap() {
+        return TABLE_ID_MAP;
+    }
+
+    @Override
+    public ImmutableBiMap<Criterion.Type, String> criterionTypeMap() {
+        return CRITERION_TYPE_MAP;
+    }
+
+    @Override
+    public Bmv2Action mapTreatment(TrafficTreatment treatment, Bmv2Configuration configuration)
+            throws Bmv2InterpreterException {
+
+        if (treatment.allInstructions().size() == 0) {
+            // No instructions means drop for us.
+            return actionWithName(DROP);
+        } else if (treatment.allInstructions().size() > 1) {
+            // Otherwise, we understand treatments with only 1 instruction.
+            throw new Bmv2InterpreterException("Treatment has multiple instructions");
+        }
+
+        Instruction instruction = treatment.allInstructions().get(0);
+
+        switch (instruction.type()) {
+            case OUTPUT:
+                OutputInstruction outInstruction = (OutputInstruction) instruction;
+                PortNumber port = outInstruction.port();
+                if (!port.isLogical()) {
+                    return buildEgressAction(port, configuration);
+                } else if (port.equals(CONTROLLER)) {
+                    return actionWithName(SEND_TO_CPU);
+                } else {
+                    throw new Bmv2InterpreterException("Egress on logical port not supported: " + port);
+                }
+            case NOACTION:
+                return actionWithName(DROP);
+            default:
+                throw new Bmv2InterpreterException("Instruction type not supported: " + instruction.type().name());
+        }
+    }
+
+    private static Bmv2Action buildEgressAction(PortNumber port, Bmv2Configuration configuration)
+            throws Bmv2InterpreterException {
+
+        int portBitWidth = configuration.action(SET_EGRESS_PORT).runtimeData(PORT).bitWidth();
+
+        try {
+            ImmutableByteSequence portBs = fitByteSequence(ImmutableByteSequence.copyFrom(port.toLong()), portBitWidth);
+            return Bmv2Action.builder()
+                    .withName(SET_EGRESS_PORT)
+                    .addParameter(portBs)
+                    .build();
+        } catch (Bmv2TranslatorUtils.ByteSequenceFitException e) {
+            throw new Bmv2InterpreterException(e.getMessage());
+        }
+    }
+
+    private static Bmv2Action actionWithName(String name) {
+        return Bmv2Action.builder().withName(name).build();
+    }
+}

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * BMv2 demo app for the ECMP configuration.
+ */
+package org.onosproject.bmv2.demo.app.ecmp;
\ No newline at end of file

+/Users/carmelo/workspace/onos-p4-dev/p4src/build/ecmp.json
\ No newline at end of file

+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright 2014-present Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.onosproject</groupId>
+        <artifactId>onos-apps</artifactId>
+        <version>1.7.0-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>onos-app-bmv2-demo</artifactId>
+
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>common</module>
+        <module>ecmp</module>
+        <module>wcmp</module>
+    </modules>
+
+</project>

+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+
+<!--
+  ~ Copyright 2016-present Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<features xmlns="http://karaf.apache.org/xmlns/features/v1.2.0" name="${project.artifactId}-${project.version}">
+    <feature name="${project.artifactId}" version="${project.version}"
+             description="${project.description}">
+        <bundle>mvn:${project.groupId}/${project.artifactId}/${project.version}</bundle>
+        <bundle>mvn:${project.groupId}/onos-app-bmv2-demo-common/${project.version}</bundle>
+    </feature>
+</features>

+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright 2016-present Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <artifactId>onos-app-bmv2-demo</artifactId>
+        <groupId>org.onosproject</groupId>
+        <version>1.7.0-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>onos-app-bmv2-demo-wcmp</artifactId>
+
+    <packaging>bundle</packaging>
+
+    <properties>
+        <onos.app.name>org.onosproject.bmv2-wcmp-fabric</onos.app.name>
+        <onos.app.title>P4/BMv2 Demo Fabric App v2 (WCMP)</onos.app.title>
+        <onos.app.category>Traffic Steering</onos.app.category>
+        <onos.app.url>http://onosproject.org</onos.app.url>
+        <onos.app.readme>P4/BMv2 demo application with WCMP support for a 2-stage clos fabric topology</onos.app.readme>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.onosproject</groupId>
+            <artifactId>onos-app-bmv2-demo-common</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+    </dependencies>
+
+</project>
\ No newline at end of file

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.bmv2.demo.app.wcmp;
+
+import com.eclipsesource.json.Json;
+import com.eclipsesource.json.JsonObject;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
+import org.apache.commons.lang3.tuple.Pair;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.bmv2.api.context.Bmv2Configuration;
+import org.onosproject.bmv2.api.context.Bmv2DefaultConfiguration;
+import org.onosproject.bmv2.api.context.Bmv2DeviceContext;
+import org.onosproject.bmv2.api.runtime.Bmv2Action;
+import org.onosproject.bmv2.api.runtime.Bmv2DeviceAgent;
+import org.onosproject.bmv2.api.runtime.Bmv2RuntimeException;
+import org.onosproject.bmv2.api.service.Bmv2Controller;
+import org.onosproject.bmv2.demo.app.common.AbstractUpgradableFabricApp;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Host;
+import org.onosproject.net.Path;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.flow.DefaultTrafficSelector;
+import org.onosproject.net.flow.DefaultTrafficTreatment;
+import org.onosproject.net.flow.FlowRule;
+import org.onosproject.net.flow.TrafficTreatment;
+import org.onosproject.net.flow.criteria.ExtensionSelector;
+import org.onosproject.net.flow.instructions.ExtensionTreatment;
+import org.onosproject.net.topology.DefaultTopologyVertex;
+import org.onosproject.net.topology.Topology;
+import org.onosproject.net.topology.TopologyGraph;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static java.util.stream.Collectors.toSet;
+import static org.onlab.packet.EthType.EtherType.IPV4;
+import static org.onosproject.bmv2.demo.app.wcmp.WcmpGroupTreatmentBuilder.groupIdOf;
+import static org.onosproject.bmv2.demo.app.wcmp.WcmpGroupTreatmentBuilder.toPrefixLengths;
+import static org.onosproject.bmv2.demo.app.wcmp.WcmpInterpreter.TABLE0;
+import static org.onosproject.bmv2.demo.app.wcmp.WcmpInterpreter.WCMP_GROUP_TABLE;
+
+/**
+ * Implementation of an upgradable fabric app for the WCMP configuration.
+ */
+@Component(immediate = true)
+public class WcmpFabricApp extends AbstractUpgradableFabricApp {
+
+    private static final String APP_NAME = "org.onosproject.bmv2-wcmp-fabric";
+    private static final String MODEL_NAME = "WCMP";
+    private static final String JSON_CONFIG_PATH = "/wcmp.json";
+
+    private static final double MULTI_PORT_WEIGHT_COEFFICIENT = 0.85;
+
+    private static final Bmv2Configuration WCMP_CONFIGURATION = loadConfiguration();
+    private static final WcmpInterpreter WCMP_INTERPRETER = new WcmpInterpreter();
+    protected static final Bmv2DeviceContext WCMP_CONTEXT = new Bmv2DeviceContext(WCMP_CONFIGURATION, WCMP_INTERPRETER);
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private Bmv2Controller bmv2Controller;
+
+    /**
+     * TODO.
+     */
+    public WcmpFabricApp() {
+        super(APP_NAME, MODEL_NAME, WCMP_CONTEXT);
+    }
+
+
+    @Override
+    public boolean initDevice(DeviceId deviceId) {
+        try {
+            Bmv2DeviceAgent agent = bmv2Controller.getAgent(deviceId);
+            for (Map.Entry<String, Bmv2Action> entry : WCMP_INTERPRETER.defaultActionsMap().entrySet()) {
+                agent.setTableDefaultAction(entry.getKey(), entry.getValue());
+            }
+            return true;
+        } catch (Bmv2RuntimeException e) {
+            log.error("Unable to init device {}: {}", deviceId, e.explain());
+            return false;
+        }
+    }
+
+    @Override
+    public List<FlowRule> generateLeafRules(DeviceId deviceId, Host srcHost, Collection<Host> dstHosts,
+                                            Collection<DeviceId> availableSpines, Topology topo)
+            throws FlowRuleGeneratorException {
+
+        Set<PortNumber> hostPortNumbers = Sets.newHashSet();
+        Set<PortNumber> fabricPortNumbers = Sets.newHashSet();
+        deviceService.getPorts(deviceId)
+                .forEach(p -> (isFabricPort(p, topo) ? fabricPortNumbers : hostPortNumbers).add(p.number()));
+
+        if (hostPortNumbers.size() != 1 || fabricPortNumbers.size() == 0) {
+            log.error("Leaf switch has invalid port configuration: hostPorts={}, fabricPorts={}",
+                      hostPortNumbers.size(), fabricPortNumbers.size());
+            throw new FlowRuleGeneratorException();
+        }
+        PortNumber hostPort = hostPortNumbers.iterator().next();
+
+        TopologyGraph graph = topologyService.getGraph(topo);
+        // Map key: spine device id, value: leaf switch ports which connect to spine in the key.
+        Map<DeviceId, Set<PortNumber>> spineToPortsMap = Maps.newHashMap();
+        graph.getEdgesFrom(new DefaultTopologyVertex(deviceId)).forEach(edge -> {
+            spineToPortsMap.putIfAbsent(edge.dst().deviceId(), Sets.newHashSet());
+            spineToPortsMap.get(edge.dst().deviceId()).add(edge.link().src().port());
+        });
+
+        double baseWeight = 1d / spineToPortsMap.size();
+
+        int numSinglePorts = (int) spineToPortsMap.values().stream().filter(s -> s.size() == 1).count();
+        int numMultiPorts = spineToPortsMap.size() - numSinglePorts;
+
+        // Reduce weight portion assigned to multi-ports to mitigate flow assignment imbalance (measured empirically).
+        double multiPortBaseWeight = baseWeight * MULTI_PORT_WEIGHT_COEFFICIENT;
+        double excess = (baseWeight - multiPortBaseWeight) * numMultiPorts;
+        double singlePortBaseWeight = baseWeight + (excess / numSinglePorts);
+
+        Map<PortNumber, Double> weighedPortNumbers = Maps.newHashMap();
+        spineToPortsMap.forEach((did, portSet) -> {
+            double base = (portSet.size() == 1) ? singlePortBaseWeight : multiPortBaseWeight;
+            double weight = base / portSet.size();
+            portSet.forEach(portNumber -> weighedPortNumbers.put(portNumber, weight));
+        });
+
+        List<FlowRule> rules = Lists.newArrayList();
+
+
+        Pair<ExtensionTreatment, List<FlowRule>> result = provisionWcmpTreatment(deviceId, weighedPortNumbers);
+        ExtensionTreatment wcmpTreatment = result.getLeft();
+        rules.addAll(result.getRight());
+
+        // From src host to dst hosts, WCMP to all fabric ports.
+        for (Host dstHost : dstHosts) {
+            FlowRule rule = flowRuleBuilder(deviceId, TABLE0)
+                    .withSelector(
+                            DefaultTrafficSelector.builder()
+                                    .matchInPort(hostPort)
+                                    .matchEthType(IPV4.ethType().toShort())
+                                    .matchEthSrc(srcHost.mac())
+                                    .matchEthDst(dstHost.mac())
+                                    .build())
+                    .withTreatment(
+                            DefaultTrafficTreatment.builder()
+                                    .extension(wcmpTreatment, deviceId)
+                                    .build())
+                    .build();
+            rules.add(rule);
+        }
+
+        // From fabric ports to src host.
+        for (PortNumber port : fabricPortNumbers) {
+            FlowRule rule = flowRuleBuilder(deviceId, TABLE0)
+                    .withSelector(
+                            DefaultTrafficSelector.builder()
+                                    .matchInPort(port)
+                                    .matchEthType(IPV4.ethType().toShort())
+                                    .matchEthDst(srcHost.mac())
+                                    .build())
+                    .withTreatment(
+                            DefaultTrafficTreatment.builder()
+                                    .setOutput(hostPort)
+                                    .build())
+                    .build();
+            rules.add(rule);
+        }
+
+        return rules;
+    }
+
+    @Override
+    public List<FlowRule> generateSpineRules(DeviceId deviceId, Collection<Host> dstHosts, Topology topo)
+            throws FlowRuleGeneratorException {
+
+        List<FlowRule> rules = Lists.newArrayList();
+
+        for (Host dstHost : dstHosts) {
+
+            Set<Path> paths = topologyService.getPaths(topo, deviceId, dstHost.location().deviceId());
+
+            if (paths.size() == 0) {
+                log.warn("Can't find any path between spine {} and host {}", deviceId, dstHost);
+                throw new FlowRuleGeneratorException();
+            }
+
+            TrafficTreatment treatment;
+
+            if (paths.size() == 1) {
+                // Only one path.
+                PortNumber port = paths.iterator().next().src().port();
+                treatment = DefaultTrafficTreatment.builder().setOutput(port).build();
+            } else {
+                // Multiple paths, do WCMP.
+                Set<PortNumber> portNumbers = paths.stream().map(p -> p.src().port()).collect(toSet());
+                double weight = 1d / portNumbers.size();
+                // Same weight for all ports.
+                Map<PortNumber, Double> weightedPortNumbers = portNumbers.stream()
+                        .collect(Collectors.toMap(p -> p, p -> weight));
+                Pair<ExtensionTreatment, List<FlowRule>> result = provisionWcmpTreatment(deviceId, weightedPortNumbers);
+                rules.addAll(result.getRight());
+                treatment = DefaultTrafficTreatment.builder().extension(result.getLeft(), deviceId).build();
+            }
+
+            FlowRule rule = flowRuleBuilder(deviceId, TABLE0)
+                    .withSelector(
+                            DefaultTrafficSelector.builder()
+                                    .matchEthType(IPV4.ethType().toShort())
+                                    .matchEthDst(dstHost.mac())
+                                    .build())
+                    .withTreatment(treatment)
+                    .build();
+
+            rules.add(rule);
+        }
+
+        return rules;
+    }
+
+    private Pair<ExtensionTreatment, List<FlowRule>> provisionWcmpTreatment(DeviceId deviceId,
+                                                                            Map<PortNumber, Double> weightedFabricPorts)
+            throws FlowRuleGeneratorException {
+
+        // Install WCMP group table entries that map from hash values to fabric ports.
+
+        int groupId = groupIdOf(deviceId, weightedFabricPorts);
+        List<PortNumber> portNumbers = Lists.newArrayList();
+        List<Double> weights = Lists.newArrayList();
+        weightedFabricPorts.forEach((p, w) -> {
+            portNumbers.add(p);
+            weights.add(w);
+        });
+        List<Integer> prefixLengths;
+        try {
+            prefixLengths = toPrefixLengths(weights);
+        } catch (WcmpGroupTreatmentBuilder.WcmpGroupException e) {
+            throw new FlowRuleGeneratorException(e);
+        }
+
+        List<FlowRule> rules = Lists.newArrayList();
+        for (int i = 0; i < portNumbers.size(); i++) {
+            ExtensionSelector extSelector = new WcmpGroupTableSelectorBuilder()
+                    .withGroupId(groupId)
+                    .withPrefixLength(prefixLengths.get(i))
+                    .build();
+            FlowRule rule = flowRuleBuilder(deviceId, WCMP_GROUP_TABLE)
+                    .withSelector(DefaultTrafficSelector.builder()
+                                          .extension(extSelector, deviceId)
+                                          .build())
+                    .withTreatment(
+                            DefaultTrafficTreatment.builder()
+                                    .setOutput(portNumbers.get(i))
+                                    .build())
+                    .build();
+            rules.add(rule);
+        }
+
+        ExtensionTreatment extTreatment = new WcmpGroupTreatmentBuilder().withGroupId(groupId).build();
+
+        return Pair.of(extTreatment, rules);
+    }
+
+    private static Bmv2Configuration loadConfiguration() {
+        try {
+            JsonObject json = Json.parse(new BufferedReader(new InputStreamReader(
+                    WcmpFabricApp.class.getResourceAsStream(JSON_CONFIG_PATH)))).asObject();
+            return Bmv2DefaultConfiguration.parse(json);
+        } catch (IOException e) {
+            throw new RuntimeException("Unable to load configuration", e);
+        }
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.bmv2.demo.app.wcmp;
+
+import com.google.common.collect.ImmutableMap;
+import org.onlab.util.ImmutableByteSequence;
+import org.onosproject.bmv2.api.runtime.Bmv2ExactMatchParam;
+import org.onosproject.bmv2.api.runtime.Bmv2ExtensionSelector;
+import org.onosproject.bmv2.api.runtime.Bmv2LpmMatchParam;
+import org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils;
+import org.onosproject.net.flow.criteria.ExtensionSelector;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils.fitByteSequence;
+import static org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils.roundToBytes;
+import static org.onosproject.bmv2.demo.app.wcmp.WcmpFabricApp.WCMP_CONTEXT;
+import static org.onosproject.bmv2.demo.app.wcmp.WcmpInterpreter.*;
+
+/**
+ * Builder of WCMP group table extension selector.
+ */
+public final class WcmpGroupTableSelectorBuilder {
+
+    private int groupId;
+    private int prefixLength;
+
+    /**
+     * Sets the WCMP group ID.
+     *
+     * @param groupId an integer value
+     * @return this
+     */
+    public WcmpGroupTableSelectorBuilder withGroupId(int groupId) {
+        this.groupId = groupId;
+        return this;
+    }
+
+    /**
+     * Sets the WCMP selector's prefix length.
+     *
+     * @param prefixLength an integer value
+     * @return this
+     */
+    public WcmpGroupTableSelectorBuilder withPrefixLength(int prefixLength) {
+        this.prefixLength = prefixLength;
+        return this;
+    }
+
+    /**
+     * Returns a new extension selector.
+     *
+     * @return an extension selector
+     */
+    public ExtensionSelector build() {
+
+        final int selectorBitWidth = WCMP_CONTEXT.configuration().headerType(WCMP_META_T).field(SELECTOR).bitWidth();
+        final int groupIdBitWidth = WCMP_CONTEXT.configuration().headerType(WCMP_META_T).field(GROUP_ID).bitWidth();
+        final ImmutableByteSequence ones = ImmutableByteSequence.ofOnes(roundToBytes(selectorBitWidth));
+
+        checkArgument(prefixLength >= 1 && prefixLength <= selectorBitWidth,
+                      "prefix length must be between 1 and " + selectorBitWidth);
+        try {
+            ImmutableByteSequence groupIdBs = fitByteSequence(ImmutableByteSequence.copyFrom(groupId), groupIdBitWidth);
+            Bmv2ExactMatchParam groupIdMatch = new Bmv2ExactMatchParam(groupIdBs);
+            Bmv2LpmMatchParam selectorMatch = new Bmv2LpmMatchParam(ones, prefixLength);
+
+            return new Bmv2ExtensionSelector(ImmutableMap.of(
+                    WCMP_META + "." + GROUP_ID, groupIdMatch,
+                    WCMP_META + "." + SELECTOR, selectorMatch));
+
+        } catch (Bmv2TranslatorUtils.ByteSequenceFitException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.bmv2.demo.app.wcmp;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import org.onlab.util.ImmutableByteSequence;
+import org.onosproject.bmv2.api.runtime.Bmv2Action;
+import org.onosproject.bmv2.api.runtime.Bmv2ExtensionTreatment;
+import org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.flow.instructions.ExtensionTreatment;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.stream.Collectors.toList;
+import static org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils.fitByteSequence;
+import static org.onosproject.bmv2.demo.app.wcmp.WcmpFabricApp.WCMP_CONTEXT;
+import static org.onosproject.bmv2.demo.app.wcmp.WcmpInterpreter.*;
+
+/**
+ * Builder of WCMP extension treatment.
+ */
+public final class WcmpGroupTreatmentBuilder {
+
+    private static final double MAX_ERROR = 0.0001;
+
+    private static final Map<DeviceId, Map<Map<PortNumber, Double>, Integer>> DEVICE_GROUP_ID_MAP = Maps.newHashMap();
+
+    private int groupId;
+
+    /**
+     * Sets the WCMP group ID.
+     *
+     * @param groupId an integer value
+     * @return this
+     */
+    public WcmpGroupTreatmentBuilder withGroupId(int groupId) {
+        this.groupId = groupId;
+        return this;
+    }
+
+    /**
+     * Returns a new extension treatment.
+     *
+     * @return an extension treatment
+     */
+    public ExtensionTreatment build() {
+        checkArgument(groupId >= 0, "group id must be a non-zero positive integer");
+        ImmutableByteSequence groupIdBs = ImmutableByteSequence.copyFrom(groupId);
+        final int groupIdBitWidth = WCMP_CONTEXT.configuration().headerType(WCMP_META_T).field(GROUP_ID).bitWidth();
+        try {
+            groupIdBs = fitByteSequence(groupIdBs, groupIdBitWidth);
+            return new Bmv2ExtensionTreatment(
+                    Bmv2Action.builder()
+                            .withName(WCMP_GROUP)
+                            .addParameter(groupIdBs)
+                            .build());
+        } catch (Bmv2TranslatorUtils.ByteSequenceFitException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static int groupIdOf(DeviceId did, Map<PortNumber, Double> weightedPorts) {
+        DEVICE_GROUP_ID_MAP.putIfAbsent(did, Maps.newHashMap());
+        // Counts the number of unique portNumber sets for each device ID.
+        // Each distinct set of portNumbers will have a unique ID.
+        return DEVICE_GROUP_ID_MAP.get(did).computeIfAbsent(weightedPorts,
+                                                            (pp) -> DEVICE_GROUP_ID_MAP.get(did).size() + 1);
+    }
+
+    public static List<Integer> toPrefixLengths(List<Double> weigths) throws WcmpGroupException {
+
+        double weightSum = weigths.stream()
+                .mapToDouble(Double::doubleValue)
+                .map(WcmpGroupTreatmentBuilder::roundDouble)
+                .sum();
+
+        if (Math.abs(weightSum - 1) > MAX_ERROR) {
+            throw new WcmpGroupException("weights sum is expected to be 1, found was " + weightSum);
+        }
+
+        final int selectorBitWidth = WCMP_CONTEXT.configuration().headerType(WCMP_META_T).field(SELECTOR).bitWidth();
+        final int availableBits = selectorBitWidth - 1;
+
+        List<Long> prefixDiffs = weigths.stream().map(w -> Math.round(w * availableBits)).collect(toList());
+
+        final long bitSum = prefixDiffs.stream().mapToLong(Long::longValue).sum();
+        final long error = availableBits - bitSum;
+
+        if (error != 0) {
+            // Lazy intuition here is that the error can be absorbed by the longest prefixDiff with the minor impact.
+            Long maxDiff = Collections.max(prefixDiffs);
+            int idx = prefixDiffs.indexOf(maxDiff);
+            prefixDiffs.remove(idx);
+            prefixDiffs.add(idx, maxDiff + error);
+        }
+        List<Integer> prefixLengths = Lists.newArrayList();
+
+        int prefix = 1;
+        for (Long p : prefixDiffs) {
+            prefixLengths.add(prefix);
+            prefix += p;
+        }
+        return ImmutableList.copyOf(prefixLengths);
+    }
+
+    private static double roundDouble(double n) {
+        // 5 digits precision.
+        return (double) Math.round(n * 100000d) / 100000d;
+    }
+
+    public static class WcmpGroupException extends Exception {
+        public WcmpGroupException(String s) {
+        }
+    }
+}

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.bmv2.demo.app.wcmp;
+
+import com.google.common.collect.ImmutableBiMap;
+import org.onlab.util.ImmutableByteSequence;
+import org.onosproject.bmv2.api.context.Bmv2Configuration;
+import org.onosproject.bmv2.api.context.Bmv2Interpreter;
+import org.onosproject.bmv2.api.context.Bmv2InterpreterException;
+import org.onosproject.bmv2.api.runtime.Bmv2Action;
+import org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.flow.TrafficTreatment;
+import org.onosproject.net.flow.criteria.Criterion;
+import org.onosproject.net.flow.instructions.Instruction;
+import org.onosproject.net.flow.instructions.Instructions.OutputInstruction;
+
+import java.util.Map;
+
+import static org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils.fitByteSequence;
+import static org.onosproject.net.PortNumber.CONTROLLER;
+
+/**
+ * Implementation of a BMv2 interpreter for the wcmp.json configuration.
+ */
+public final class WcmpInterpreter implements Bmv2Interpreter {
+
+    protected static final String WCMP_META_T = "wcmp_meta_t";
+    protected static final String WCMP_META = "wcmp_meta";
+    protected static final String SELECTOR = "selector";
+    protected static final String GROUP_ID = "groupId";
+    protected static final String WCMP_GROUP = "wcmp_group";
+    protected static final String WCMP_SET_SELECTOR = "wcmp_set_selector";
+    protected static final String WCMP_SET_SELECTOR_TABLE = "wcmp_set_selector_table";
+    protected static final String WCMP_GROUP_TABLE = "wcmp_group_table";
+    protected static final String TABLE0 = "table0";
+    protected static final String SEND_TO_CPU = "send_to_cpu";
+    protected static final String DROP = "_drop";
+    protected static final String SET_EGRESS_PORT = "set_egress_port";
+    protected static final String PORT = "port";
+
+    private static final ImmutableBiMap<Criterion.Type, String> CRITERION_TYPE_MAP = ImmutableBiMap.of(
+            Criterion.Type.IN_PORT, "standard_metadata.ingress_port",
+            Criterion.Type.ETH_DST, "ethernet.dstAddr",
+            Criterion.Type.ETH_SRC, "ethernet.srcAddr",
+            Criterion.Type.ETH_TYPE, "ethernet.etherType");
+
+    private static final ImmutableBiMap<Integer, String> TABLE_ID_MAP = ImmutableBiMap.of(
+            0, TABLE0,
+            1, WCMP_GROUP_TABLE);
+
+    private static final Map<String, Bmv2Action> DEFAULT_ACTIONS_MAP = ImmutableBiMap.of(
+            WCMP_SET_SELECTOR_TABLE, actionWithName(WCMP_SET_SELECTOR));
+
+    @Override
+    public ImmutableBiMap<Integer, String> tableIdMap() {
+        return TABLE_ID_MAP;
+    }
+
+    @Override
+    public ImmutableBiMap<Criterion.Type, String> criterionTypeMap() {
+        return CRITERION_TYPE_MAP;
+    }
+
+    public Map<String, Bmv2Action> defaultActionsMap() {
+        return DEFAULT_ACTIONS_MAP;
+    }
+
+    @Override
+    public Bmv2Action mapTreatment(TrafficTreatment treatment, Bmv2Configuration configuration)
+            throws Bmv2InterpreterException {
+
+        if (treatment.allInstructions().size() == 0) {
+            // No instructions means drop for us.
+            return actionWithName(DROP);
+        } else if (treatment.allInstructions().size() > 1) {
+            // Otherwise, we understand treatments with only 1 instruction.
+            throw new Bmv2InterpreterException("Treatment has multiple instructions");
+        }
+
+        Instruction instruction = treatment.allInstructions().get(0);
+
+        switch (instruction.type()) {
+            case OUTPUT:
+                OutputInstruction outInstruction = (OutputInstruction) instruction;
+                PortNumber port = outInstruction.port();
+                if (!port.isLogical()) {
+                    return buildEgressAction(port, configuration);
+                } else if (port.equals(CONTROLLER)) {
+                    return actionWithName(SEND_TO_CPU);
+                } else {
+                    throw new Bmv2InterpreterException("Egress on logical port not supported: " + port);
+                }
+            case NOACTION:
+                return actionWithName(DROP);
+            default:
+                throw new Bmv2InterpreterException("Instruction type not supported: " + instruction.type().name());
+        }
+    }
+
+    private static Bmv2Action buildEgressAction(PortNumber port, Bmv2Configuration configuration)
+            throws Bmv2InterpreterException {
+
+        int portBitWidth = configuration.action(SET_EGRESS_PORT).runtimeData(PORT).bitWidth();
+
+        try {
+            ImmutableByteSequence portBs = fitByteSequence(ImmutableByteSequence.copyFrom(port.toLong()), portBitWidth);
+            return Bmv2Action.builder()
+                    .withName(SET_EGRESS_PORT)
+                    .addParameter(portBs)
+                    .build();
+        } catch (Bmv2TranslatorUtils.ByteSequenceFitException e) {
+            throw new Bmv2InterpreterException(e.getMessage());
+        }
+    }
+
+    private static Bmv2Action actionWithName(String name) {
+        return Bmv2Action.builder().withName(name).build();
+    }
+}

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * BMv2 demo app for the WCMP configuration.
+ */
+package org.onosproject.bmv2.demo.app.wcmp;
\ No newline at end of file

+/Users/carmelo/workspace/onos-p4-dev/p4src/build/wcmp.json
\ No newline at end of file

@@ -71,6 +71,7 @@
         <module>graphitemetrics</module>
         <module>xosclient</module>
         <module>scalablegateway</module>
+        <module>bmv2-demo</module>
     </modules>