summaryrefslogtreecommitdiffstats
path: root/vbd/impl
diff options
context:
space:
mode:
authorRobert Varga <nite@hq.sk>2016-01-30 15:25:19 +0100
committerRobert Varga <nite@hq.sk>2016-01-31 18:21:24 +0100
commit42887f769a3ac57963110925a1c2965c2b25bac6 (patch)
tree4d5f47c3ad19767c99964dc5a8c80391e9242c99 /vbd/impl
parentcb22508bc344123078a1caea7d39da49583f0ab0 (diff)
Add Virtual Bridge Domain implementation
Change-Id: I427b709ac0af1ade365bc60148ddf778f7be458a Signed-off-by: Robert Varga <nite@hq.sk>
Diffstat (limited to 'vbd/impl')
-rw-r--r--vbd/impl/pom.xml63
-rw-r--r--vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/BridgeDomain.java169
-rw-r--r--vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/TopologyMonitor.java159
-rw-r--r--vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/VirtualBridgeDomainManager.java65
-rw-r--r--vbd/impl/vbridge-workflow.txt106
5 files changed, 562 insertions, 0 deletions
diff --git a/vbd/impl/pom.xml b/vbd/impl/pom.xml
new file mode 100644
index 000000000..3d6d55aea
--- /dev/null
+++ b/vbd/impl/pom.xml
@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- vi: set et smarttab sw=4 tabstop=4: -->
+<!--
+ Copyright (c) 2015 Cisco and/or its affiliates.
+ 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">
+
+ <parent>
+ <groupId>io.fd.honeycomb.common</groupId>
+ <artifactId>impl-parent</artifactId>
+ <version>1.0.0-SNAPSHOT</version>
+ <relativePath>../../common/impl-parent</relativePath>
+ </parent>
+
+ <modelVersion>4.0.0</modelVersion>
+ <groupId>io.fd.honeycomb.vbd</groupId>
+ <artifactId>vbd-impl</artifactId>
+ <version>1.0.0-SNAPSHOT</version>
+ <packaging>bundle</packaging>
+
+ <dependencyManagement>
+ <dependencies>
+ <dependency>
+ <groupId>io.fd.honeycomb.vbd</groupId>
+ <artifactId>vbd-artifacts</artifactId>
+ <version>1.0.0-SNAPSHOT</version>
+ <type>pom</type>
+ <scope>import</scope>
+ </dependency>
+ </dependencies>
+ </dependencyManagement>
+
+ <dependencies>
+ <dependency>
+ <groupId>${project.groupId}</groupId>
+ <artifactId>vbd-api</artifactId>
+ </dependency>
+
+ <!-- Testing Dependencies -->
+ <dependency>
+ <groupId>junit</groupId>
+ <artifactId>junit</artifactId>
+ <scope>test</scope>
+ </dependency>
+
+ <dependency>
+ <groupId>org.mockito</groupId>
+ <artifactId>mockito-all</artifactId>
+ <scope>test</scope>
+ </dependency>
+ </dependencies>
+</project>
diff --git a/vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/BridgeDomain.java b/vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/BridgeDomain.java
new file mode 100644
index 000000000..aff03b2a6
--- /dev/null
+++ b/vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/BridgeDomain.java
@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2016 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package io.fd.honeycomb.vbd.impl;
+
+import com.google.common.base.Preconditions;
+import java.util.Collection;
+import javax.annotation.concurrent.GuardedBy;
+import org.opendaylight.controller.md.sal.binding.api.BindingTransactionChain;
+import org.opendaylight.controller.md.sal.binding.api.DataBroker;
+import org.opendaylight.controller.md.sal.binding.api.DataObjectModification;
+import org.opendaylight.controller.md.sal.binding.api.DataObjectModification.ModificationType;
+import org.opendaylight.controller.md.sal.binding.api.DataTreeChangeListener;
+import org.opendaylight.controller.md.sal.binding.api.DataTreeIdentifier;
+import org.opendaylight.controller.md.sal.binding.api.DataTreeModification;
+import org.opendaylight.controller.md.sal.binding.api.WriteTransaction;
+import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.Topology1;
+import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.Topology;
+import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.TopologyKey;
+import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.Node;
+import org.opendaylight.yangtools.concepts.ListenerRegistration;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.KeyedInstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Implementation of a single Virtual Bridge Domain. It is bound to a particular network topology instance, manages
+ * bridge members and projects state into the operational data store.
+ */
+final class BridgeDomain implements DataTreeChangeListener<Topology> {
+ private static final Logger LOG = LoggerFactory.getLogger(BridgeDomain.class);
+ private final KeyedInstanceIdentifier<Topology, TopologyKey> topology;
+
+ @GuardedBy("this")
+ private final BindingTransactionChain chain;
+ private final ListenerRegistration<?> reg;
+ private Topology1 config;
+
+ private BridgeDomain(final DataBroker dataBroker, final KeyedInstanceIdentifier<Topology, TopologyKey> topology,
+ final BindingTransactionChain chain) {
+ this.topology = Preconditions.checkNotNull(topology);
+ this.chain = Preconditions.checkNotNull(chain);
+
+ reg = dataBroker.registerDataTreeChangeListener(
+ new DataTreeIdentifier<>(LogicalDatastoreType.CONFIGURATION, topology), this);
+ }
+
+ static BridgeDomain create(final DataBroker dataBroker,
+ final KeyedInstanceIdentifier<Topology, TopologyKey> topology, final BindingTransactionChain chain) {
+
+ LOG.debug("Wiping operational state of {}", topology);
+
+ final WriteTransaction tx = chain.newWriteOnlyTransaction();
+ tx.delete(LogicalDatastoreType.OPERATIONAL, topology);
+ tx.submit();
+
+ return new BridgeDomain(dataBroker, topology, chain);
+ }
+
+ synchronized void forceStop() {
+ LOG.info("Bridge domain {} for {} going down", this, topology);
+ reg.close();
+ chain.close();
+ LOG.info("Bridge domain {} for {} is down", this, topology);
+ }
+
+ synchronized void stop() {
+ LOG.debug("Bridge domain {} for {} shutting down", this, topology);
+
+ final WriteTransaction tx = chain.newWriteOnlyTransaction();
+ tx.delete(LogicalDatastoreType.OPERATIONAL, topology);
+ tx.submit();
+ chain.close();
+ }
+
+ @Override
+ public synchronized void onDataTreeChanged(final Collection<DataTreeModification<Topology>> changes) {
+ for (DataTreeModification<Topology> c : changes) {
+ LOG.debug("Domain {} for {} processing change {}", this, topology, c);
+
+ final DataObjectModification<Topology> mod = c.getRootNode();
+ switch (mod.getModificationType()) {
+ case DELETE:
+ LOG.debug("Topology {} deleted, expecting shutdown", topology);
+ break;
+ case SUBTREE_MODIFIED:
+ // First check if the configuration has changed
+ final DataObjectModification<Topology1> newConfig = mod.getModifiedAugmentation(Topology1.class);
+ if (newConfig != null) {
+ if (newConfig.getModificationType() != ModificationType.DELETE) {
+ LOG.debug("Topology {} modified configuration {}", topology, newConfig);
+ updateConfiguration(newConfig);
+ } else {
+ // FIXME: okay, what can we do about this one?
+ LOG.error("Topology {} configuration deleted, good luck!", topology);
+ }
+ }
+
+ for (DataObjectModification<? extends DataObject> child : mod.getModifiedChildren()) {
+ LOG.debug("Topology {} modified child {}", topology, child);
+
+ if (Node.class.isAssignableFrom(child.getDataType())) {
+ modifyNode((DataObjectModification<Node>) child);
+ }
+ }
+
+ break;
+ case WRITE:
+ final Topology data = mod.getDataAfter();
+
+ // Read configuration
+ final Topology1 config = data.getAugmentation(Topology1.class);
+ if (config != null) {
+ setConfiguration(config);
+ } else {
+ LOG.error("Topology {} has no configuration, good luck!", topology);
+ }
+
+ // FIXME: deal with nodes
+
+ break;
+ default:
+ LOG.warn("Unhandled topology modification {}", mod);
+ break;
+ }
+ }
+ }
+
+ private void modifyNode(final DataObjectModification<Node> child) {
+ switch (child.getModificationType()) {
+ case DELETE:
+ LOG.debug("Topology {} node {} deleted", topology, child.getIdentifier());
+ // FIXME: do something
+ break;
+ case SUBTREE_MODIFIED:
+ LOG.debug("Topology {} node {} modified", topology, child.getIdentifier());
+ // FIXME: do something
+ break;
+ case WRITE:
+ LOG.debug("Topology {} node {} created", topology, child.getIdentifier());
+ // FIXME: do something
+ break;
+ default:
+ LOG.warn("Unhandled node modification {} in topology {}", child, topology);
+ break;
+ }
+ }
+
+ private void setConfiguration(final Topology1 config) {
+ LOG.debug("Topology {} configuration set to {}", topology, config);
+
+ this.config = config;
+ }
+
+ @GuardedBy("this")
+ private void updateConfiguration(final DataObjectModification<Topology1> mod) {
+ LOG.debug("Topology {} configuration changed", topology);
+
+ // FIXME: do something smarter
+ setConfiguration(mod.getDataAfter());
+ }
+}
diff --git a/vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/TopologyMonitor.java b/vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/TopologyMonitor.java
new file mode 100644
index 000000000..b2e52c37e
--- /dev/null
+++ b/vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/TopologyMonitor.java
@@ -0,0 +1,159 @@
+/*
+ * Copyright (c) 2016 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package io.fd.honeycomb.vbd.impl;
+
+import com.google.common.base.Preconditions;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+import javax.annotation.concurrent.GuardedBy;
+import org.opendaylight.controller.md.sal.binding.api.BindingTransactionChain;
+import org.opendaylight.controller.md.sal.binding.api.DataBroker;
+import org.opendaylight.controller.md.sal.binding.api.DataObjectModification;
+import org.opendaylight.controller.md.sal.binding.api.DataTreeChangeListener;
+import org.opendaylight.controller.md.sal.binding.api.DataTreeModification;
+import org.opendaylight.controller.md.sal.common.api.data.AsyncTransaction;
+import org.opendaylight.controller.md.sal.common.api.data.TransactionChain;
+import org.opendaylight.controller.md.sal.common.api.data.TransactionChainListener;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.network.topology.topology.topology.types.VbridgeTopology;
+import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.Topology;
+import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.TopologyKey;
+import org.opendaylight.yangtools.yang.binding.KeyedInstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Class responsible for monitoring /network-topology/topology and activating a {@link BridgeDomain} when a particular
+ * topology is marked as a bridge domain.
+ */
+final class TopologyMonitor implements DataTreeChangeListener<VbridgeTopology>, AutoCloseable {
+ private static final Logger LOG = LoggerFactory.getLogger(TopologyMonitor.class);
+
+ @GuardedBy("this")
+ private final Map<TopologyKey, BridgeDomain> domains = new HashMap<>();
+ private final DataBroker dataBroker;
+
+ TopologyMonitor(final DataBroker dataBroker) {
+ this.dataBroker = Preconditions.checkNotNull(dataBroker);
+ }
+
+ @Override
+ public synchronized void onDataTreeChanged(final Collection<DataTreeModification<VbridgeTopology>> changes) {
+ for (DataTreeModification<VbridgeTopology> c : changes) {
+ @SuppressWarnings("unchecked")
+ final KeyedInstanceIdentifier<Topology, TopologyKey> topology =
+ (KeyedInstanceIdentifier<Topology, TopologyKey>) c.getRootPath().getRootIdentifier()
+ .firstIdentifierOf(Topology.class);
+
+ Preconditions.checkArgument(!topology.isWildcarded(), "Wildcard topology %s is not supported", topology);
+
+ final DataObjectModification<VbridgeTopology> mod = c.getRootNode();
+ switch (mod.getModificationType()) {
+ case DELETE:
+ LOG.debug("Topology {} removed", topology);
+ stopDomain(topology);
+ break;
+ case WRITE:
+ LOG.debug("Topology {} added", topology);
+ startDomain(topology);
+ break;
+ default:
+ LOG.warn("Ignoring unhandled modification type {}", mod.getModificationType());
+ break;
+ }
+ }
+ }
+
+ private synchronized void completeDomain(final KeyedInstanceIdentifier<Topology, TopologyKey> topology) {
+ LOG.debug("Bridge domain for {} completed operation", topology);
+ domains.remove(topology);
+
+ synchronized (domains) {
+ domains.notify();
+ }
+ }
+
+ private synchronized void restartDomain(final KeyedInstanceIdentifier<Topology, TopologyKey> topology) {
+ final BridgeDomain prev = domains.remove(topology);
+ if (prev == null) {
+ LOG.warn("No domain for {}, not restarting", topology);
+ return;
+ }
+
+ prev.forceStop();
+ startDomain(topology);
+ }
+
+ @GuardedBy("this")
+ private void startDomain(final KeyedInstanceIdentifier<Topology, TopologyKey> topology) {
+ final BridgeDomain prev = domains.get(topology.getKey());
+ if (prev != null) {
+ LOG.warn("Bridge domain {} for {} already started", prev, topology);
+ return;
+ }
+
+ LOG.debug("Starting bridge domain for {}", topology);
+
+ final BindingTransactionChain chain = dataBroker.createTransactionChain(new TransactionChainListener() {
+ @Override
+ public void onTransactionChainSuccessful(final TransactionChain<?, ?> chain) {
+ completeDomain(topology);
+ }
+
+ @Override
+ public void onTransactionChainFailed(final TransactionChain<?, ?> chain,
+ final AsyncTransaction<?, ?> transaction, final Throwable cause) {
+ LOG.warn("Bridge domain for {} failed, restarting it", cause);
+ restartDomain(topology);
+ }
+ });
+
+ final BridgeDomain domain = BridgeDomain.create(dataBroker, topology, chain);
+ domains.put(topology.getKey(), domain);
+
+ LOG.debug("Bridge domain {} for {} started", domain, topology);
+ }
+
+ @GuardedBy("this")
+ private void stopDomain(final KeyedInstanceIdentifier<Topology, TopologyKey> topology) {
+ final BridgeDomain domain = domains.remove(topology.getKey());
+ if (domain == null) {
+ LOG.warn("Bridge domain for {} not present", topology);
+ return;
+ }
+
+ domain.stop();
+ }
+
+ @Override
+ public synchronized void close() {
+ LOG.debug("Topology monitor {} shut down started", this);
+
+ for (Entry<TopologyKey, BridgeDomain> e : domains.entrySet()) {
+ LOG.debug("Shutting down bridge domain {} (key {})", e.getValue(), e.getKey());
+ e.getValue().stop();
+ }
+
+ while (!domains.isEmpty()) {
+ LOG.debug("Waiting for domains for {} to complete", domains.keySet());
+ synchronized (domains) {
+ try {
+ domains.wait();
+ } catch (InterruptedException e) {
+ LOG.warn("Interrupted while waiting for domain shutdown, {} have not completed yet",
+ domains.keySet(), e);
+ break;
+ }
+ }
+ }
+
+ LOG.debug("Topology monitor {} shut down completed", this);
+ }
+}
diff --git a/vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/VirtualBridgeDomainManager.java b/vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/VirtualBridgeDomainManager.java
new file mode 100644
index 000000000..37da73159
--- /dev/null
+++ b/vbd/impl/src/main/java/io/fd/honeycomb/vbd/impl/VirtualBridgeDomainManager.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2016 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package io.fd.honeycomb.vbd.impl;
+
+import com.google.common.base.Preconditions;
+import javax.annotation.Nonnull;
+import org.opendaylight.controller.md.sal.binding.api.DataBroker;
+import org.opendaylight.controller.md.sal.binding.api.DataTreeIdentifier;
+import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.TopologyTypes1;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.network.topology.topology.topology.types.VbridgeTopology;
+import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.NetworkTopology;
+import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.Topology;
+import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.TopologyTypes;
+import org.opendaylight.yangtools.concepts.ListenerRegistration;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Tip for the Virtual Bridge Domain implementation. This class is instantiated when the application is started
+ * and {@link #close()}d when it is shut down.
+ */
+public final class VirtualBridgeDomainManager implements AutoCloseable {
+ private static final Logger LOG = LoggerFactory.getLogger(VirtualBridgeDomainManager.class);
+ private static final DataTreeIdentifier<VbridgeTopology> LISTEN_TREE =
+ new DataTreeIdentifier<>(LogicalDatastoreType.CONFIGURATION,
+ InstanceIdentifier.builder(NetworkTopology.class).child(Topology.class).child(TopologyTypes.class)
+ .augmentation(TopologyTypes1.class).child(VbridgeTopology.class).build());
+
+ private final ListenerRegistration<TopologyMonitor> reg;
+ private boolean closed;
+
+ private VirtualBridgeDomainManager(final ListenerRegistration<TopologyMonitor> reg) {
+ this.reg = Preconditions.checkNotNull(reg);
+ }
+
+ public static VirtualBridgeDomainManager create(@Nonnull final DataBroker dataBroker) {
+ final ListenerRegistration<TopologyMonitor> reg =
+ dataBroker.registerDataTreeChangeListener(LISTEN_TREE, new TopologyMonitor(dataBroker));
+
+ return new VirtualBridgeDomainManager(reg);
+ }
+
+ @Override
+ public void close() {
+ if (!closed) {
+ LOG.debug("Virtual Bridge Domain manager shut down started");
+
+ final TopologyMonitor monitor = reg.getInstance();
+ reg.close();
+ LOG.debug("Topology monitor {} unregistered", monitor);
+ monitor.close();
+
+ closed = true;
+ LOG.debug("Virtual Bridge Domain manager shut down completed");
+ }
+ }
+}
diff --git a/vbd/impl/vbridge-workflow.txt b/vbd/impl/vbridge-workflow.txt
new file mode 100644
index 000000000..86ba544f4
--- /dev/null
+++ b/vbd/impl/vbridge-workflow.txt
@@ -0,0 +1,106 @@
+VPP Inventory/Topology
+----------------------
+
+- VPP management done through netconf-node-topology
+- Mount point management done by sal-netconf-connector
+
+
+Virtual Bridge Domain management
+--------------------------------
+
+Prerequisite: configured netconf-node-topology
+
+1) Create a Virtual Bridge Domain:
+
+ A) The UI creates a network topology instance in Controller Data Store
+ with:
+
+ - topology-types/vbridge-topology container
+ - tunnel-type set to tunnel-type-vxlan
+ - tunnel-parameters/vxlan/vni set to appropriate value
+ - any bridge domain parameters from v3po:bridge-domain-attributes
+
+ B) The Controller App receives a DataTreeChangeNotification about the
+ topology instance being created
+
+2) Assign a VPP into a Virtual Bridge Domain
+ Prerequisite: Virtual Bridge Domain exists
+
+ A) The UI creates a 'node' within the VBD network topology in the
+ Controller Data Store with:
+
+ - bridge-member container
+ - supporting-node pointing to the VPP node in the
+ netconf-node-topology
+
+ B) The Controller App receives a DataTreeChangeNotification about the
+ node being added, and:
+
+ - it looks at the supporting-node in the netconf topology and if the
+ node is connected:
+ - it creates a bridge domain with the name matching this VBD name,
+ copying bridge domain parameters from VBD Topology configuration
+ into the VPP
+ - once that succeeds it creates the corresponding
+ supporting-bridge-domain leaf in the Controller's operational
+ datastore. The leaf contains a RESTCONF-encoded instance
+ identifier of the bridge domain created in the VPP, relative to
+ that VPP's mount point.
+
+3) Assigning a physical VPP interface into a Virtual Bridge Domain
+ Prerequisite: The VPP itself has been added to the Virtual Bridge
+ Domain
+
+ A) The UI creates a 'termination-point' inside the 'node' added in 2),
+ with:
+
+ - user-interface, containing RESTCONF-encoded instance identifier
+ of the VPP interface, relative to that VPP's mount point in config
+ data store.
+
+ B) The Controller App receives a notification of this being done and:
+ - looks if the VPP is connected, if it is, the app will:
+ - add the interface into the VPP's bridge domain configuration
+
+Inverse operations are achieved by the UI deleting the corresponding nodes in
+the Controller's configuration data store.
+
+
+Virtual Bridge Domain tunnel management
+---------------------------------------
+
+Operation is triggered by adding more than one VPP into the virtual bridge
+domain, for sake of clarity this describes only one-way tunnel setup. The
+process is repeated until a full mesh is achieved (FUTURE: spanning tree?).
+The process is also simplified for demo purposes, real-world deployment would
+deal with day-1 configuration and multi-provider setups.
+
+Demo assumption: there is exactly one interface with a VRF and IP address
+assined, which is the interface to be used for tunnels
+
+The Controller App looks at the Source VPP:
+- it finds the only interface with VRF and IP addresses. It will use this VRF
+ as the vxlan tunnel VRF. It will use the IP address as the vxlan tunnel
+ source.
+
+The Controller App looks at the Destination VPP:
+- it finds the only interface with VRF and IP addresses. It will use the IP
+ address as the vxlan tunnel destination.
+
+The Controller App sets up the tunnel on the source VPP, using the VNI
+configured for this Virtual Bridge Domain and IP addresses as detailed above.
+
+The controller app creates a new termination point within the VBD's the
+controller's operational data store, under the
+node representing the source VPP, with a generated ID (mechanism is TBD, must
+not conflict with VPP names) and 'tunnel-interface' leaf, which points to the
+vxlan interface created on the source VPP (e.g. VPP config state).
+
+This process is repeated in the reverse direction.
+
+Once that is done, the controller app will create a link from the newly-created
+source TP to the newly-created destination TP in the controller's operational
+data store, with leaf 'tunnel' pointing to the source VPP's interface operation
+state (e.g. VPP vxlan oper state). A reverse link will be created, with the
+'tunnel' leaf pointing to the destination VPP's interface state.
+