diff --git a/assignment-client/src/assets/AssetServer.cpp b/assignment-client/src/assets/AssetServer.cpp
index b8c4629b90..22ed01fd00 100644
--- a/assignment-client/src/assets/AssetServer.cpp
+++ b/assignment-client/src/assets/AssetServer.cpp
@@ -901,7 +901,7 @@ void AssetServer::handleAssetUpload(QSharedPointer<ReceivedMessage> message, Sha
 
 
     if (canWriteToAssetServer) {
-        qCDebug(asset_server) << "Starting an UploadAssetTask for upload from" << uuidStringWithoutCurlyBraces(message->getSourceID());
+        qCDebug(asset_server) << "Starting an UploadAssetTask for upload from" << message->getSourceID();
 
         auto task = new UploadAssetTask(message, senderNode, _filesDirectory, _filesizeLimit);
         _transferTaskPool.start(task);
diff --git a/assignment-client/src/audio/AudioMixer.cpp b/assignment-client/src/audio/AudioMixer.cpp
index 8af4eec934..34eb138697 100644
--- a/assignment-client/src/audio/AudioMixer.cpp
+++ b/assignment-client/src/audio/AudioMixer.cpp
@@ -117,12 +117,13 @@ void AudioMixer::queueAudioPacket(QSharedPointer<ReceivedMessage> message, Share
 void AudioMixer::queueReplicatedAudioPacket(QSharedPointer<ReceivedMessage> message) {
     // make sure we have a replicated node for the original sender of the packet
     auto nodeList = DependencyManager::get<NodeList>();
-
-    QUuid nodeID =  QUuid::fromRfc4122(message->readWithoutCopy(NUM_BYTES_RFC4122_UUID));
+    
+    // Node ID is now part of user data, since replicated audio packets are non-sourced.
+    QUuid nodeID = QUuid::fromRfc4122(message->readWithoutCopy(NUM_BYTES_RFC4122_UUID));
 
     auto replicatedNode = nodeList->addOrUpdateNode(nodeID, NodeType::Agent,
                                                     message->getSenderSockAddr(), message->getSenderSockAddr(),
-                                                    true, true);
+                                                    Node::NULL_LOCAL_ID, true, true);
     replicatedNode->setLastHeardMicrostamp(usecTimestampNow());
 
     // construct a "fake" audio received message from the byte array and packet list information
@@ -136,7 +137,7 @@ void AudioMixer::queueReplicatedAudioPacket(QSharedPointer<ReceivedMessage> mess
 
     auto replicatedMessage = QSharedPointer<ReceivedMessage>::create(audioData, rewrittenType,
                                                                      versionForPacketType(rewrittenType),
-                                                                     message->getSenderSockAddr(), nodeID);
+                                                                     message->getSenderSockAddr(), Node::NULL_LOCAL_ID);
 
     getOrCreateClientData(replicatedNode.data())->queuePacket(replicatedMessage, replicatedNode);
 }
diff --git a/assignment-client/src/avatars/AvatarMixer.cpp b/assignment-client/src/avatars/AvatarMixer.cpp
index 929941c05c..29340f6474 100644
--- a/assignment-client/src/avatars/AvatarMixer.cpp
+++ b/assignment-client/src/avatars/AvatarMixer.cpp
@@ -74,7 +74,7 @@ SharedNodePointer addOrUpdateReplicatedNode(const QUuid& nodeID, const HifiSockA
     auto replicatedNode = DependencyManager::get<NodeList>()->addOrUpdateNode(nodeID, NodeType::Agent,
                                                                               senderSockAddr,
                                                                               senderSockAddr,
-                                                                              true, true);
+                                                                              Node::NULL_LOCAL_ID, true, true);
 
     replicatedNode->setLastHeardMicrostamp(usecTimestampNow());
 
@@ -112,8 +112,8 @@ void AvatarMixer::handleReplicatedPacket(QSharedPointer<ReceivedMessage> message
 void AvatarMixer::handleReplicatedBulkAvatarPacket(QSharedPointer<ReceivedMessage> message) {
     while (message->getBytesLeftToRead()) {
         // first, grab the node ID for this replicated avatar
+        // Node ID is now part of user data, since ReplicatedBulkAvatarPacket is non-sourced.
         auto nodeID = QUuid::fromRfc4122(message->readWithoutCopy(NUM_BYTES_RFC4122_UUID));
-
         // make sure we have an upstream replicated node that matches
         auto replicatedNode = addOrUpdateReplicatedNode(nodeID, message->getSenderSockAddr());
 
@@ -127,7 +127,7 @@ void AvatarMixer::handleReplicatedBulkAvatarPacket(QSharedPointer<ReceivedMessag
         // construct a "fake" avatar data received message from the byte array and packet list information
         auto replicatedMessage = QSharedPointer<ReceivedMessage>::create(avatarByteArray, PacketType::AvatarData,
                                                                          versionForPacketType(PacketType::AvatarData),
-                                                                         message->getSenderSockAddr(), nodeID);
+                                                                         message->getSenderSockAddr(), Node::NULL_LOCAL_ID);
 
         // queue up the replicated avatar data with the client data for the replicated node
         auto start = usecTimestampNow();
diff --git a/domain-server/src/DomainGatekeeper.cpp b/domain-server/src/DomainGatekeeper.cpp
index 9f24036e92..d78f0aaeb3 100644
--- a/domain-server/src/DomainGatekeeper.cpp
+++ b/domain-server/src/DomainGatekeeper.cpp
@@ -14,6 +14,7 @@
 #include <openssl/err.h>
 #include <openssl/rsa.h>
 #include <openssl/x509.h>
+#include <random>
 
 #include <AccountManager.h>
 #include <Assignment.h>
@@ -26,7 +27,7 @@ using SharedAssignmentPointer = QSharedPointer<Assignment>;
 DomainGatekeeper::DomainGatekeeper(DomainServer* server) :
     _server(server)
 {
-
+    initLocalIDManagement();
 }
 
 void DomainGatekeeper::addPendingAssignedNode(const QUuid& nodeUUID, const QUuid& assignmentUUID,
@@ -529,8 +530,10 @@ SharedNodePointer DomainGatekeeper::addVerifiedNodeFromConnectRequest(const Node
 
     auto limitedNodeList = DependencyManager::get<LimitedNodeList>();
 
+    Node::LocalID newLocalID = findOrCreateLocalID(nodeID);
     SharedNodePointer newNode = limitedNodeList->addOrUpdateNode(nodeID, nodeConnection.nodeType,
-                                                                 nodeConnection.publicSockAddr, nodeConnection.localSockAddr);
+                                                                 nodeConnection.publicSockAddr, nodeConnection.localSockAddr,
+                                                                 newLocalID);
 
     // So that we can send messages to this node at will - we need to activate the correct socket on this node now
     newNode->activateMatchingOrNewSymmetricSocket(discoveredSocket);
@@ -1020,3 +1023,31 @@ void DomainGatekeeper::refreshGroupsCache() {
     _server->_settingsManager.debugDumpGroupsState();
 #endif
 }
+
+void DomainGatekeeper::initLocalIDManagement() {
+    std::uniform_int_distribution<quint16> sixteenBitRand;
+    std::random_device randomDevice;
+    std::default_random_engine engine { randomDevice() };
+    _currentLocalID = sixteenBitRand(engine);
+    // Ensure increment is odd.
+    _idIncrement = sixteenBitRand(engine) | 1;
+}
+
+Node::LocalID DomainGatekeeper::findOrCreateLocalID(const QUuid& uuid) {
+    auto existingLocalIDIt = _uuidToLocalID.find(uuid);
+    if (existingLocalIDIt != _uuidToLocalID.end()) {
+        return existingLocalIDIt->second;
+    }
+
+    assert(_localIDs.size() < std::numeric_limits<LocalIDs::value_type>::max() - 2);
+
+    Node::LocalID newLocalID;
+    do {
+        newLocalID = _currentLocalID;
+        _currentLocalID += _idIncrement;
+    } while (newLocalID == Node::NULL_LOCAL_ID || _localIDs.find(newLocalID) != _localIDs.end());
+
+    _uuidToLocalID.emplace(uuid, newLocalID);
+    _localIDs.insert(newLocalID);
+    return newLocalID;
+}
diff --git a/domain-server/src/DomainGatekeeper.h b/domain-server/src/DomainGatekeeper.h
index 09db075e07..8402e58559 100644
--- a/domain-server/src/DomainGatekeeper.h
+++ b/domain-server/src/DomainGatekeeper.h
@@ -15,6 +15,7 @@
 #define hifi_DomainGatekeeper_h
 
 #include <unordered_map>
+#include <unordered_set>
 
 #include <QtCore/QObject>
 #include <QtNetwork/QNetworkReply>
@@ -41,6 +42,8 @@ public:
     
     void removeICEPeer(const QUuid& peerUUID) { _icePeers.remove(peerUUID); }
 
+    Node::LocalID findOrCreateLocalID(const QUuid& uuid);
+
     static void sendProtocolMismatchConnectionDenial(const HifiSockAddr& senderSockAddr);
 public slots:
     void processConnectRequestPacket(QSharedPointer<ReceivedMessage> message);
@@ -120,6 +123,16 @@ private:
     void getGroupMemberships(const QString& username);
     // void getIsGroupMember(const QString& username, const QUuid groupID);
     void getDomainOwnerFriendsList();
+
+    // Local ID management.
+    void initLocalIDManagement();
+    using UUIDToLocalID = std::unordered_map<QUuid, Node::LocalID> ;
+    using LocalIDs = std::unordered_set<Node::LocalID>;
+    LocalIDs _localIDs;
+    UUIDToLocalID _uuidToLocalID;
+
+    Node::LocalID _currentLocalID;
+    Node::LocalID _idIncrement;
 };
 
 
diff --git a/domain-server/src/DomainServer.cpp b/domain-server/src/DomainServer.cpp
index b054b5cf8e..ac157979bb 100644
--- a/domain-server/src/DomainServer.cpp
+++ b/domain-server/src/DomainServer.cpp
@@ -593,8 +593,8 @@ bool DomainServer::isPacketVerified(const udt::Packet& packet) {
 
     if (!PacketTypeEnum::getNonSourcedPackets().contains(headerType)) {
         // this is a sourced packet - first check if we have a node that matches
-        QUuid sourceID = NLPacket::sourceIDInHeader(packet);
-        SharedNodePointer sourceNode = nodeList->nodeWithUUID(sourceID);
+        Node::LocalID localSourceID = NLPacket::sourceIDInHeader(packet);
+        SharedNodePointer sourceNode = nodeList->nodeWithLocalID(localSourceID);
 
         if (sourceNode) {
             // unverified DS packets (due to a lack of connection secret between DS + node)
@@ -612,14 +612,12 @@ bool DomainServer::isPacketVerified(const udt::Packet& packet) {
                 return nodeList->isPacketVerifiedWithSource(packet, sourceNode.data());
             } else {
                 HIFI_FDEBUG("Packet of type" << headerType
-                    << "received from unmatched IP for UUID" << uuidStringWithoutCurlyBraces(sourceID));
-
+                    << "received from unmatched IP for UUID" << uuidStringWithoutCurlyBraces(sourceNode->getUUID()));
                 return false;
             }
         } else {
             HIFI_FDEBUG("Packet of type" << headerType
-                << "received from unknown node with UUID" << uuidStringWithoutCurlyBraces(sourceID));
-
+                << "received from unknown node with UUID" << uuidStringWithoutCurlyBraces(sourceNode->getUUID()));
             return false;
         }
     }
@@ -683,6 +681,10 @@ void DomainServer::setupNodeListAndAssignments() {
         }
     }
 
+    // Create our own short session ID.
+    Node::LocalID serverSessionLocalID = _gatekeeper.findOrCreateLocalID(nodeList->getSessionUUID());
+    nodeList->setSessionLocalID(serverSessionLocalID);
+
     if (isMetaverseDomain) {
         // see if we think we're a temp domain (we have an API key) or a full domain
         const auto& temporaryDomainKey = DependencyManager::get<AccountManager>()->getTemporaryDomainKey(getID());
@@ -1112,7 +1114,8 @@ void DomainServer::handleConnectedNode(SharedNodePointer newNode) {
 }
 
 void DomainServer::sendDomainListToNode(const SharedNodePointer& node, const HifiSockAddr &senderSockAddr) {
-    const int NUM_DOMAIN_LIST_EXTENDED_HEADER_BYTES = NUM_BYTES_RFC4122_UUID + NUM_BYTES_RFC4122_UUID + 2;
+    const int NUM_DOMAIN_LIST_EXTENDED_HEADER_BYTES = NUM_BYTES_RFC4122_UUID + NLPacket::NUM_BYTES_LOCALID + 
+        NUM_BYTES_RFC4122_UUID + NLPacket::NUM_BYTES_LOCALID + 4;
 
     // setup the extended header for the domain list packets
     // this data is at the beginning of each of the domain list packets
@@ -1122,7 +1125,9 @@ void DomainServer::sendDomainListToNode(const SharedNodePointer& node, const Hif
     auto limitedNodeList = DependencyManager::get<LimitedNodeList>();
 
     extendedHeaderStream << limitedNodeList->getSessionUUID();
+    extendedHeaderStream << limitedNodeList->getSessionLocalID();
     extendedHeaderStream << node->getUUID();
+    extendedHeaderStream << node->getLocalID();
     extendedHeaderStream << node->getPermissions();
 
     auto domainListPackets = NLPacketList::create(PacketType::DomainList, extendedHeader);
@@ -2841,7 +2846,7 @@ void DomainServer::updateReplicationNodes(ReplicationServerDirection direction)
                         // manually add the replication node to our node list
                         auto node = nodeList->addOrUpdateNode(QUuid::createUuid(), replicationServer.nodeType,
                                                               replicationServer.sockAddr, replicationServer.sockAddr,
-                                                              false, direction == Upstream);
+                                                              Node::NULL_LOCAL_ID, false, direction == Upstream);
                         node->setIsForcedNeverSilent(true);
 
                         qDebug() << "Adding" << (direction == Upstream ? "upstream" : "downstream")
@@ -3141,13 +3146,12 @@ void DomainServer::processNodeDisconnectRequestPacket(QSharedPointer<ReceivedMes
     // This packet has been matched to a source node and they're asking not to be in the domain anymore
     auto limitedNodeList = DependencyManager::get<LimitedNodeList>();
 
-    const QUuid& nodeUUID = message->getSourceID();
-
-    qDebug() << "Received a disconnect request from node with UUID" << nodeUUID;
+    auto localID = message->getSourceID();
+    qDebug() << "Received a disconnect request from node with local ID" << localID;
 
     // we want to check what type this node was before going to kill it so that we can avoid sending the RemovedNode
     // packet to nodes that don't care about this type
-    auto nodeToKill = limitedNodeList->nodeWithUUID(nodeUUID);
+    auto nodeToKill = limitedNodeList->nodeWithLocalID(localID);
 
     if (nodeToKill) {
         handleKillNode(nodeToKill);
@@ -3415,7 +3419,7 @@ void DomainServer::handleDomainContentReplacementFromURLRequest(QSharedPointer<R
 }
 
 void DomainServer::handleOctreeFileReplacementRequest(QSharedPointer<ReceivedMessage> message) {
-    auto node = DependencyManager::get<NodeList>()->nodeWithUUID(message->getSourceID());
+    auto node = DependencyManager::get<NodeList>()->nodeWithLocalID(message->getSourceID());
     if (node->getCanReplaceContent()) {
         handleOctreeFileReplacement(message->readAll());
     }
diff --git a/interface/src/octree/OctreePacketProcessor.cpp b/interface/src/octree/OctreePacketProcessor.cpp
index 122b58c057..0c2883a9a4 100644
--- a/interface/src/octree/OctreePacketProcessor.cpp
+++ b/interface/src/octree/OctreePacketProcessor.cpp
@@ -71,7 +71,7 @@ void OctreePacketProcessor::processPacket(QSharedPointer<ReceivedMessage> messag
     if (message->getVersion() != versionForPacketType(message->getType())) {
         static QMultiMap<QUuid, PacketType> versionDebugSuppressMap;
 
-        const QUuid& senderUUID = message->getSourceID();
+        const QUuid& senderUUID = sendingNode->getUUID();
         if (!versionDebugSuppressMap.contains(senderUUID, packetType)) {
             
             qDebug() << "Was stats packet? " << wasStatsPacket;
diff --git a/libraries/audio/src/InboundAudioStream.cpp b/libraries/audio/src/InboundAudioStream.cpp
index 72acc7fcf6..172ec9411a 100644
--- a/libraries/audio/src/InboundAudioStream.cpp
+++ b/libraries/audio/src/InboundAudioStream.cpp
@@ -120,8 +120,8 @@ int InboundAudioStream::parseData(ReceivedMessage& message) {
     // parse sequence number and track it
     quint16 sequence;
     message.readPrimitive(&sequence);
-    SequenceNumberStats::ArrivalInfo arrivalInfo = _incomingSequenceNumberStats.sequenceNumberReceived(sequence,
-                                                                                                       message.getSourceID());
+    SequenceNumberStats::ArrivalInfo arrivalInfo =
+        _incomingSequenceNumberStats.sequenceNumberReceived(sequence, message.getSourceID());
     QString codecInPacket = message.readString();
 
     packetReceivedUpdateTimingStats();
@@ -186,7 +186,7 @@ int InboundAudioStream::parseData(ReceivedMessage& message) {
                         _mismatchedAudioCodecCount = 0;
 
                         // inform others of the mismatch
-                        auto sendingNode = DependencyManager::get<NodeList>()->nodeWithUUID(message.getSourceID());
+                        auto sendingNode = DependencyManager::get<NodeList>()->nodeWithLocalID(message.getSourceID());
                         if (sendingNode) {
                             emit mismatchedAudioCodec(sendingNode, _selectedCodecName, codecInPacket);
                             qDebug(audio) << "Codec mismatch threshold exceeded, SelectedAudioFormat(" << _selectedCodecName << " ) sent";
diff --git a/libraries/networking/src/DomainHandler.h b/libraries/networking/src/DomainHandler.h
index 7137b8084d..2d4712209d 100644
--- a/libraries/networking/src/DomainHandler.h
+++ b/libraries/networking/src/DomainHandler.h
@@ -45,6 +45,9 @@ public:
     const QUuid& getUUID() const { return _uuid; }
     void setUUID(const QUuid& uuid);
 
+    Node::LocalID getLocalID() const { return _localID; }
+    void setLocalID(Node::LocalID localID) { _localID = localID; }
+
     QString getHostname() const { return _domainURL.host(); }
 
     const QHostAddress& getIP() const { return _sockAddr.getAddress(); }
@@ -185,6 +188,7 @@ private:
     void hardReset();
 
     QUuid _uuid;
+    Node::LocalID _localID;
     QUrl _domainURL;
     HifiSockAddr _sockAddr;
     QUuid _assignmentUUID;
diff --git a/libraries/networking/src/LimitedNodeList.cpp b/libraries/networking/src/LimitedNodeList.cpp
index d7eb472d65..aaf1b58a0a 100644
--- a/libraries/networking/src/LimitedNodeList.cpp
+++ b/libraries/networking/src/LimitedNodeList.cpp
@@ -132,6 +132,16 @@ void LimitedNodeList::setSessionUUID(const QUuid& sessionUUID) {
     }
 }
 
+Node::LocalID LimitedNodeList::getSessionLocalID() const {
+    QReadLocker readLock { &_sessionUUIDLock };
+    return _sessionLocalID;
+}
+
+void LimitedNodeList::setSessionLocalID(Node::LocalID sessionLocalID) {
+    QWriteLocker lock { &_sessionUUIDLock };
+    _sessionLocalID = sessionLocalID;
+}
+
 void LimitedNodeList::setPermissions(const NodePermissions& newPermissions) {
     NodePermissions originalPermissions = _permissions;
 
@@ -230,13 +240,16 @@ bool LimitedNodeList::packetVersionMatch(const udt::Packet& packet) {
                 senderString = QString("%1:%2").arg(senderSockAddr.getAddress().toString()).arg(senderSockAddr.getPort());
             }
         } else {
-            sourceID = NLPacket::sourceIDInHeader(packet);
+            SharedNodePointer sourceNode = nodeWithLocalID(NLPacket::sourceIDInHeader(packet));
+            if (sourceNode) {
+                sourceID = sourceNode->getUUID();
 
-            hasBeenOutput = sourcedVersionDebugSuppressMap.contains(sourceID, headerType);
+                hasBeenOutput = sourcedVersionDebugSuppressMap.contains(sourceID, headerType);
 
-            if (!hasBeenOutput) {
-                sourcedVersionDebugSuppressMap.insert(sourceID, headerType);
-                senderString = uuidStringWithoutCurlyBraces(sourceID.toString());
+                if (!hasBeenOutput) {
+                    sourcedVersionDebugSuppressMap.insert(sourceID, headerType);
+                    senderString = uuidStringWithoutCurlyBraces(sourceID.toString());
+                }
             }
         }
 
@@ -289,17 +302,20 @@ bool LimitedNodeList::packetSourceAndHashMatchAndTrackBandwidth(const udt::Packe
             return true;
         }
     } else {
-        QUuid sourceID = NLPacket::sourceIDInHeader(packet);
-
+        NLPacket::LocalID sourceLocalID = Node::NULL_LOCAL_ID;
         // check if we were passed a sourceNode hint or if we need to look it up
         if (!sourceNode) {
             // figure out which node this is from
-            SharedNodePointer matchingNode = nodeWithUUID(sourceID);
+            sourceLocalID = NLPacket::sourceIDInHeader(packet);
+
+            SharedNodePointer matchingNode = nodeWithLocalID(sourceLocalID);
             sourceNode = matchingNode.data();
         }
+        
+        QUuid sourceID = sourceNode ? sourceNode->getUUID() : QUuid();
 
         if (!sourceNode &&
-            sourceID == getDomainUUID() &&
+            sourceLocalID == getDomainLocalID() &&
             packet.getSenderSockAddr() == getDomainSockAddr() &&
             PacketTypeEnum::getDomainSourcedPackets().contains(headerType)) {
             // This is a packet sourced by the domain server
@@ -357,7 +373,7 @@ void LimitedNodeList::collectPacketStats(const NLPacket& packet) {
 
 void LimitedNodeList::fillPacketHeader(const NLPacket& packet, HMACAuth* hmacAuth) {
     if (!PacketTypeEnum::getNonSourcedPackets().contains(packet.getType())) {
-        packet.writeSourceID(getSessionUUID());
+        packet.writeSourceID(getSessionLocalID());
     }
 
     if (hmacAuth
@@ -541,6 +557,13 @@ SharedNodePointer LimitedNodeList::nodeWithUUID(const QUuid& nodeUUID) {
     return it == _nodeHash.cend() ? SharedNodePointer() : it->second;
  }
 
+SharedNodePointer LimitedNodeList::nodeWithLocalID(Node::LocalID localID) const {
+    QReadLocker readLocker(&_nodeMutex);
+
+    LocalIDMapping::const_iterator idIter = _localIDMap.find(localID);
+    return idIter == _localIDMap.cend() ? nullptr : idIter->second;
+}
+
 void LimitedNodeList::eraseAllNodes() {
     QSet<SharedNodePointer> killedNodes;
 
@@ -549,6 +572,8 @@ void LimitedNodeList::eraseAllNodes() {
         // and then remove them from the hash
         QWriteLocker writeLocker(&_nodeMutex);
 
+        _localIDMap.clear();
+
         if (_nodeHash.size() > 0) {
             qCDebug(networking) << "LimitedNodeList::eraseAllNodes() removing all nodes from NodeList.";
 
@@ -624,7 +649,7 @@ void LimitedNodeList::handleNodeKill(const SharedNodePointer& node, ConnectionID
 
 SharedNodePointer LimitedNodeList::addOrUpdateNode(const QUuid& uuid, NodeType_t nodeType,
                                                    const HifiSockAddr& publicSocket, const HifiSockAddr& localSocket,
-                                                   bool isReplicated, bool isUpstream,
+                                                   Node::LocalID localID, bool isReplicated, bool isUpstream,
                                                    const QUuid& connectionSecret, const NodePermissions& permissions) {
     QReadLocker readLocker(&_nodeMutex);
     NodeHash::const_iterator it = _nodeHash.find(uuid);
@@ -638,6 +663,7 @@ SharedNodePointer LimitedNodeList::addOrUpdateNode(const QUuid& uuid, NodeType_t
         matchingNode->setConnectionSecret(connectionSecret);
         matchingNode->setIsReplicated(isReplicated);
         matchingNode->setIsUpstream(isUpstream || NodeType::isUpstream(nodeType));
+        matchingNode->setLocalID(localID);
 
         return matchingNode;
     } else {
@@ -652,6 +678,7 @@ SharedNodePointer LimitedNodeList::addOrUpdateNode(const QUuid& uuid, NodeType_t
         newNode->setIsUpstream(isUpstream || NodeType::isUpstream(nodeType));
         newNode->setConnectionSecret(connectionSecret);
         newNode->setPermissions(permissions);
+        newNode->setLocalID(localID);
 
         // move the newly constructed node to the LNL thread
         newNode->moveToThread(thread());
@@ -677,6 +704,7 @@ SharedNodePointer LimitedNodeList::addOrUpdateNode(const QUuid& uuid, NodeType_t
 
                 auto oldSoloNode = previousSoloIt->second;
 
+                _localIDMap.unsafe_erase(oldSoloNode->getLocalID());
                 _nodeHash.unsafe_erase(previousSoloIt);
                 handleNodeKill(oldSoloNode);
 
@@ -692,6 +720,7 @@ SharedNodePointer LimitedNodeList::addOrUpdateNode(const QUuid& uuid, NodeType_t
 #else
         _nodeHash.emplace(newNode->getUUID(), newNodePointer);
 #endif
+        _localIDMap.emplace(localID, newNodePointer);
         readLocker.unlock();
 
         qCDebug(networking) << "Added" << *newNode;
@@ -819,6 +848,7 @@ void LimitedNodeList::removeSilentNodes() {
         if (!node->isForcedNeverSilent()
             && (usecTimestampNow() - node->getLastHeardMicrostamp()) > (NODE_SILENCE_THRESHOLD_MSECS * USECS_PER_MSEC)) {
             // call the NodeHash erase to get rid of this node
+            _localIDMap.unsafe_erase(node->getLocalID());
             it = _nodeHash.unsafe_erase(it);
 
             killedNodes.insert(node);
diff --git a/libraries/networking/src/LimitedNodeList.h b/libraries/networking/src/LimitedNodeList.h
index d4517bdcec..05374bbfbb 100644
--- a/libraries/networking/src/LimitedNodeList.h
+++ b/libraries/networking/src/LimitedNodeList.h
@@ -110,6 +110,8 @@ public:
     Q_ENUM(ConnectionStep);
     QUuid getSessionUUID() const;
     void setSessionUUID(const QUuid& sessionUUID);
+    Node::LocalID getSessionLocalID() const;
+    void setSessionLocalID(Node::LocalID localID);
 
     void setPermissions(const NodePermissions& newPermissions);
     bool isAllowedEditor() const { return _permissions.can(NodePermissions::Permission::canAdjustLocks); }
@@ -130,6 +132,7 @@ public:
 
     virtual bool isDomainServer() const { return true; }
     virtual QUuid getDomainUUID() const { assert(false); return QUuid(); }
+    virtual Node::LocalID getDomainLocalID() const { assert(false); return Node::NULL_LOCAL_ID; }
     virtual HifiSockAddr getDomainSockAddr() const { assert(false); return HifiSockAddr(); }
 
     // use sendUnreliablePacket to send an unreliable packet (that you do not need to move)
@@ -157,11 +160,12 @@ public:
     size_t size() const { QReadLocker readLock(&_nodeMutex); return _nodeHash.size(); }
 
     SharedNodePointer nodeWithUUID(const QUuid& nodeUUID);
+    SharedNodePointer nodeWithLocalID(Node::LocalID localID) const;
 
     SharedNodePointer addOrUpdateNode(const QUuid& uuid, NodeType_t nodeType,
                                       const HifiSockAddr& publicSocket, const HifiSockAddr& localSocket,
-                                      bool isReplicated = false, bool isUpstream = false,
-                                      const QUuid& connectionSecret = QUuid(),
+                                      Node::LocalID localID = Node::NULL_LOCAL_ID, bool isReplicated = false,
+                                      bool isUpstream = false, const QUuid& connectionSecret = QUuid(),
                                       const NodePermissions& permissions = DEFAULT_AGENT_PERMISSIONS);
 
     static bool parseSTUNResponse(udt::BasePacket* packet, QHostAddress& newPublicAddress, uint16_t& newPublicPort);
@@ -430,6 +434,9 @@ private slots:
 private:
     mutable QReadWriteLock _sessionUUIDLock;
     QUuid _sessionUUID;
+    using LocalIDMapping = tbb::concurrent_unordered_map<Node::LocalID, SharedNodePointer>;
+    LocalIDMapping _localIDMap;
+    Node::LocalID _sessionLocalID { 0 };
 };
 
 #endif // hifi_LimitedNodeList_h
diff --git a/libraries/networking/src/NLPacket.cpp b/libraries/networking/src/NLPacket.cpp
index 93274843a6..3355e1cd6b 100644
--- a/libraries/networking/src/NLPacket.cpp
+++ b/libraries/networking/src/NLPacket.cpp
@@ -16,7 +16,7 @@
 int NLPacket::localHeaderSize(PacketType type) {
     bool nonSourced = PacketTypeEnum::getNonSourcedPackets().contains(type);
     bool nonVerified = PacketTypeEnum::getNonVerifiedPackets().contains(type);
-    qint64 optionalSize = (nonSourced ? 0 : NUM_BYTES_RFC4122_UUID) + ((nonSourced || nonVerified) ? 0 : NUM_BYTES_MD5_HASH);
+    qint64 optionalSize = (nonSourced ? 0 : NUM_BYTES_LOCALID) + ((nonSourced || nonVerified) ? 0 : NUM_BYTES_MD5_HASH);
     return sizeof(PacketType) + sizeof(PacketVersion) + optionalSize;
 }
 int NLPacket::totalHeaderSize(PacketType type, bool isPartOfMessage) {
@@ -141,19 +141,22 @@ PacketVersion NLPacket::versionInHeader(const udt::Packet& packet) {
     return *reinterpret_cast<const PacketVersion*>(packet.getData() + headerOffset + sizeof(PacketType));
 }
 
-QUuid NLPacket::sourceIDInHeader(const udt::Packet& packet) {
+NLPacket::LocalID NLPacket::sourceIDInHeader(const udt::Packet& packet) {
     int offset = Packet::totalHeaderSize(packet.isPartOfMessage()) + sizeof(PacketType) + sizeof(PacketVersion);
-    return QUuid::fromRfc4122(QByteArray::fromRawData(packet.getData() + offset, NUM_BYTES_RFC4122_UUID));
+    return *reinterpret_cast<const LocalID*>(packet.getData() + offset);
 }
 
 QByteArray NLPacket::verificationHashInHeader(const udt::Packet& packet) {
-    int offset = Packet::totalHeaderSize(packet.isPartOfMessage()) + sizeof(PacketType) + sizeof(PacketVersion) + NUM_BYTES_RFC4122_UUID;
+    int offset = Packet::totalHeaderSize(packet.isPartOfMessage()) + sizeof(PacketType) +
+        sizeof(PacketVersion) + NUM_BYTES_LOCALID;
     return QByteArray(packet.getData() + offset, NUM_BYTES_MD5_HASH);
 }
 
 QByteArray NLPacket::hashForPacketAndHMAC(const udt::Packet& packet, HMACAuth& hash) {
     int offset = Packet::totalHeaderSize(packet.isPartOfMessage()) + sizeof(PacketType) + sizeof(PacketVersion)
-        + NUM_BYTES_RFC4122_UUID + NUM_BYTES_MD5_HASH;
+        + NUM_BYTES_LOCALID + NUM_BYTES_MD5_HASH;
+    
+    // add the packet payload and the connection UUID
     hash.addData(packet.getData() + offset, packet.getDataSize() - offset);
     auto hashResult { hash.result() };
     return QByteArray((const char*) hashResult.data(), (int) hashResult.size());
@@ -199,11 +202,12 @@ void NLPacket::readSourceID() {
     }
 }
 
-void NLPacket::writeSourceID(const QUuid& sourceID) const {
+void NLPacket::writeSourceID(LocalID sourceID) const {
     Q_ASSERT(!PacketTypeEnum::getNonSourcedPackets().contains(_type));
     
     auto offset = Packet::totalHeaderSize(isPartOfMessage()) + sizeof(PacketType) + sizeof(PacketVersion);
-    memcpy(_packet.get() + offset, sourceID.toRfc4122().constData(), NUM_BYTES_RFC4122_UUID);
+
+    memcpy(_packet.get() + offset, &sourceID, sizeof(sourceID));
     
     _sourceID = sourceID;
 }
@@ -213,7 +217,7 @@ void NLPacket::writeVerificationHash(HMACAuth& hmacAuth) const {
              !PacketTypeEnum::getNonVerifiedPackets().contains(_type));
     
     auto offset = Packet::totalHeaderSize(isPartOfMessage()) + sizeof(PacketType) + sizeof(PacketVersion)
-                + NUM_BYTES_RFC4122_UUID;
+                + NUM_BYTES_LOCALID;
 
     QByteArray verificationHash = hashForPacketAndHMAC(*this, hmacAuth);
     
diff --git a/libraries/networking/src/NLPacket.h b/libraries/networking/src/NLPacket.h
index 302598f77c..4103f2068e 100644
--- a/libraries/networking/src/NLPacket.h
+++ b/libraries/networking/src/NLPacket.h
@@ -24,31 +24,29 @@ class NLPacket : public udt::Packet {
     Q_OBJECT
 public:
     //
-    //    |      BYTE     |      BYTE     |      BYTE     |      BYTE     |
+    //    NLPacket format:
     //
+    //    |      BYTE     |      BYTE     |      BYTE     |      BYTE     |
     //     0                   1                   2                   3
     //     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    //    |  Packet Type  |    Version    |                               |
-    //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
+    //    |  Packet Type  |    Version    | Local Node ID - sourced only  |
+    //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //    |                                                               |
-    //    |                       Node UUID - 16 bytes                    |
-    //    |                   (ONLY FOR SOURCED PACKETS)                  |
-    //    |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    //    |                               |                               |
-    //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
+    //    |                 MD5 Verification - 16 bytes                   |
+    //    |                 (ONLY FOR VERIFIED PACKETS)                   |
     //    |                                                               |
-    //    |                   MD5 Verification - 16 bytes                 |
-    //    |                   (ONLY FOR VERIFIED PACKETS)                 |
-    //    |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    //    |                               |                               |
-    //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
-    //    NLPacket Header Format
+    //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    //
 
+    using LocalID = NetworkLocalID;
+    static const LocalID NULL_LOCAL_ID = 0;
+    
+    static const int NUM_BYTES_LOCALID = sizeof(LocalID);
     // this is used by the Octree classes - must be known at compile time
     static const int MAX_PACKET_HEADER_SIZE =
         sizeof(udt::Packet::SequenceNumberAndBitField) + sizeof(udt::Packet::MessageNumberAndBitField) +
-        sizeof(PacketType) + sizeof(PacketVersion) + NUM_BYTES_RFC4122_UUID + NUM_BYTES_MD5_HASH;
+        sizeof(PacketType) + sizeof(PacketVersion) + NUM_BYTES_LOCALID + NUM_BYTES_MD5_HASH;
     
     static std::unique_ptr<NLPacket> create(PacketType type, qint64 size = -1,
                     bool isReliable = false, bool isPartOfMessage = false, PacketVersion version = 0);
@@ -71,7 +69,7 @@ public:
     static PacketType typeInHeader(const udt::Packet& packet);
     static PacketVersion versionInHeader(const udt::Packet& packet);
     
-    static QUuid sourceIDInHeader(const udt::Packet& packet);
+    static LocalID sourceIDInHeader(const udt::Packet& packet);
     static QByteArray verificationHashInHeader(const udt::Packet& packet);
     static QByteArray hashForPacketAndHMAC(const udt::Packet& packet, HMACAuth& hash);
     
@@ -81,9 +79,9 @@ public:
     PacketVersion getVersion() const { return _version; }
     void setVersion(PacketVersion version);
 
-    const QUuid& getSourceID() const { return _sourceID; }
+    LocalID getSourceID() const { return _sourceID; }
     
-    void writeSourceID(const QUuid& sourceID) const;
+    void writeSourceID(LocalID sourceID) const;
     void writeVerificationHash(HMACAuth& hmacAuth) const;
 
 protected:
@@ -108,7 +106,7 @@ protected:
     
     PacketType _type;
     PacketVersion _version;
-    mutable QUuid _sourceID;
+    mutable LocalID _sourceID;
 };
 
 #endif // hifi_NLPacket_h
diff --git a/libraries/networking/src/NLPacketList.h b/libraries/networking/src/NLPacketList.h
index 910d39f71b..9c50033ca7 100644
--- a/libraries/networking/src/NLPacketList.h
+++ b/libraries/networking/src/NLPacketList.h
@@ -22,7 +22,7 @@ public:
                                                 bool isReliable = false, bool isOrdered = false);
     
     PacketVersion getVersion() const { return _packetVersion; }
-    const QUuid& getSourceID() const { return _sourceID; }
+    NLPacket::LocalID getSourceID() const { return _sourceID; }
 
     qint64 getMaxSegmentSize() const override { return NLPacket::maxPayloadSize(_packetType, _isOrdered); }
     
@@ -37,7 +37,7 @@ private:
 
 
     PacketVersion _packetVersion;
-    QUuid _sourceID;
+    NLPacket::LocalID _sourceID;
 };
 
 Q_DECLARE_METATYPE(QSharedPointer<NLPacketList>)
diff --git a/libraries/networking/src/NetworkPeer.cpp b/libraries/networking/src/NetworkPeer.cpp
index b52c54c468..6d384ba558 100644
--- a/libraries/networking/src/NetworkPeer.cpp
+++ b/libraries/networking/src/NetworkPeer.cpp
@@ -23,6 +23,7 @@
 #include <Trace.h>
 #include "NodeType.h"
 
+const NetworkPeer::LocalID NetworkPeer::NULL_LOCAL_ID;
 
 NetworkPeer::NetworkPeer(QObject* parent) :
     QObject(parent),
diff --git a/libraries/networking/src/NetworkPeer.h b/libraries/networking/src/NetworkPeer.h
index 9842768b37..462daa1ed2 100644
--- a/libraries/networking/src/NetworkPeer.h
+++ b/libraries/networking/src/NetworkPeer.h
@@ -18,6 +18,7 @@
 #include <QtCore/QTimer>
 #include <QtCore/QUuid>
 
+#include "UUID.h"
 #include "HifiSockAddr.h"
 
 const QString ICE_SERVER_HOSTNAME = "localhost";
@@ -39,6 +40,12 @@ public:
     const QUuid& getUUID() const { return _uuid; }
     void setUUID(const QUuid& uuid) { _uuid = uuid; }
 
+    using LocalID = NetworkLocalID;
+    static const LocalID NULL_LOCAL_ID = 0;
+
+    LocalID getLocalID() const { return _localID; }
+    void setLocalID(LocalID localID) { _localID = localID; }
+
     void softReset();
     void reset();
 
@@ -99,6 +106,7 @@ protected:
     void setActiveSocket(HifiSockAddr* discoveredSocket);
 
     QUuid _uuid;
+    LocalID _localID { 0 };
 
     HifiSockAddr _publicSocket;
     HifiSockAddr _localSocket;
diff --git a/libraries/networking/src/Node.cpp b/libraries/networking/src/Node.cpp
index 132d27d311..7979b36e30 100644
--- a/libraries/networking/src/Node.cpp
+++ b/libraries/networking/src/Node.cpp
@@ -169,6 +169,7 @@ QDataStream& operator<<(QDataStream& out, const Node& node) {
     out << node._localSocket;
     out << node._permissions;
     out << node._isReplicated;
+    out << node._localID;
     return out;
 }
 
@@ -179,6 +180,7 @@ QDataStream& operator>>(QDataStream& in, Node& node) {
     in >> node._localSocket;
     in >> node._permissions;
     in >> node._isReplicated;
+    in >> node._localID;
     return in;
 }
 
@@ -189,7 +191,7 @@ QDebug operator<<(QDebug debug, const Node& node) {
     } else {
         debug.nospace() << " (" << node.getType() << ")";
     }
-    debug << " " << node.getUUID().toString().toLocal8Bit().constData() << " ";
+    debug << " " << node.getUUID().toString().toLocal8Bit().constData() << "(" << node.getLocalID() << ") ";
     debug.nospace() << node.getPublicSocket() << "/" << node.getLocalSocket();
     return debug.nospace();
 }
diff --git a/libraries/networking/src/NodeList.cpp b/libraries/networking/src/NodeList.cpp
index fdb503eee5..cfe81a58af 100644
--- a/libraries/networking/src/NodeList.cpp
+++ b/libraries/networking/src/NodeList.cpp
@@ -624,13 +624,21 @@ void NodeList::processDomainServerList(QSharedPointer<ReceivedMessage> message)
         return;
     }
 
-    // pull our owner UUID from the packet, it's always the first thing
+    Node::LocalID domainLocalID;
+    packetStream >> domainLocalID;
+
+    // pull our owner (ie. session) UUID from the packet, it's always the first thing
+    // The short (16 bit) ID comes next.
     QUuid newUUID;
+    Node::LocalID newLocalID;
     packetStream >> newUUID;
+    packetStream >> newLocalID;
+    setSessionLocalID(newLocalID);
     setSessionUUID(newUUID);
 
     // if this was the first domain-server list from this domain, we've now connected
     if (!_domainHandler.isConnected()) {
+        _domainHandler.setLocalID(newLocalID);
         _domainHandler.setUUID(domainUUID);
         _domainHandler.setIsConnected(true);
 
@@ -668,12 +676,14 @@ void NodeList::processDomainServerRemovedNode(QSharedPointer<ReceivedMessage> me
 void NodeList::parseNodeFromPacketStream(QDataStream& packetStream) {
     // setup variables to read into from QDataStream
     qint8 nodeType;
-    QUuid nodeUUID, connectionUUID;
+    QUuid nodeUUID, connectionSecretUUID;
     HifiSockAddr nodePublicSocket, nodeLocalSocket;
     NodePermissions permissions;
     bool isReplicated;
+    Node::LocalID sessionLocalID;
 
-    packetStream >> nodeType >> nodeUUID >> nodePublicSocket >> nodeLocalSocket >> permissions >> isReplicated;
+    packetStream >> nodeType >> nodeUUID >> nodePublicSocket >> nodeLocalSocket >> permissions
+        >> isReplicated >> sessionLocalID;
 
     // if the public socket address is 0 then it's reachable at the same IP
     // as the domain server
@@ -681,10 +691,10 @@ void NodeList::parseNodeFromPacketStream(QDataStream& packetStream) {
         nodePublicSocket.setAddress(_domainHandler.getIP());
     }
 
-    packetStream >> connectionUUID;
+    packetStream >> connectionSecretUUID;
 
-    SharedNodePointer node = addOrUpdateNode(nodeUUID, nodeType, nodePublicSocket,
-                                             nodeLocalSocket, isReplicated, false, connectionUUID, permissions);
+    SharedNodePointer node = addOrUpdateNode(nodeUUID, nodeType, nodePublicSocket, nodeLocalSocket,
+                                             sessionLocalID, isReplicated, false, connectionSecretUUID, permissions);
 
     // nodes that are downstream or upstream of our own type are kept alive when we hear about them from the domain server
     // and always have their public socket as their active socket
diff --git a/libraries/networking/src/NodeList.h b/libraries/networking/src/NodeList.h
index 7e3a7c2bd7..9595c5da84 100644
--- a/libraries/networking/src/NodeList.h
+++ b/libraries/networking/src/NodeList.h
@@ -94,6 +94,7 @@ public:
 
     virtual bool isDomainServer() const override { return false; }
     virtual QUuid getDomainUUID() const override { return _domainHandler.getUUID(); }
+    virtual Node::LocalID getDomainLocalID() const override { return _domainHandler.getLocalID(); }
     virtual HifiSockAddr getDomainSockAddr() const override { return _domainHandler.getSockAddr(); }
 
 public slots:
diff --git a/libraries/networking/src/PacketReceiver.cpp b/libraries/networking/src/PacketReceiver.cpp
index 27b57ef26c..fe2a273d61 100644
--- a/libraries/networking/src/PacketReceiver.cpp
+++ b/libraries/networking/src/PacketReceiver.cpp
@@ -261,10 +261,9 @@ void PacketReceiver::handleVerifiedMessage(QSharedPointer<ReceivedMessage> recei
     
     SharedNodePointer matchingNode;
     
-    if (!receivedMessage->getSourceID().isNull()) {
-        matchingNode = nodeList->nodeWithUUID(receivedMessage->getSourceID());
+    if (receivedMessage->getSourceID() != Node::NULL_LOCAL_ID) {
+        matchingNode = nodeList->nodeWithLocalID(receivedMessage->getSourceID());
     }
-    
     QMutexLocker packetListenerLocker(&_packetListenerLock);
     
     auto it = _messageListenerMap.find(receivedMessage->getType());
diff --git a/libraries/networking/src/ReceivedMessage.cpp b/libraries/networking/src/ReceivedMessage.cpp
index 00b16908ce..e1a036b041 100644
--- a/libraries/networking/src/ReceivedMessage.cpp
+++ b/libraries/networking/src/ReceivedMessage.cpp
@@ -43,7 +43,7 @@ ReceivedMessage::ReceivedMessage(NLPacket& packet)
 }
 
 ReceivedMessage::ReceivedMessage(QByteArray byteArray, PacketType packetType, PacketVersion packetVersion,
-                const HifiSockAddr& senderSockAddr, QUuid sourceID) :
+                const HifiSockAddr& senderSockAddr, NLPacket::LocalID sourceID) :
     _data(byteArray),
     _headData(_data.mid(0, HEAD_DATA_SIZE)),
     _numPackets(1),
diff --git a/libraries/networking/src/ReceivedMessage.h b/libraries/networking/src/ReceivedMessage.h
index ae51e7592a..af87ef75af 100644
--- a/libraries/networking/src/ReceivedMessage.h
+++ b/libraries/networking/src/ReceivedMessage.h
@@ -25,7 +25,7 @@ public:
     ReceivedMessage(const NLPacketList& packetList);
     ReceivedMessage(NLPacket& packet);
     ReceivedMessage(QByteArray byteArray, PacketType packetType, PacketVersion packetVersion,
-                    const HifiSockAddr& senderSockAddr, QUuid sourceID = QUuid());
+                    const HifiSockAddr& senderSockAddr, NLPacket::LocalID sourceID = NLPacket::NULL_LOCAL_ID);
 
     QByteArray getMessage() const { return _data; }
     const char* getRawMessage() const { return _data.constData(); }
@@ -40,7 +40,7 @@ public:
     bool failed() const { return _failed; }
     bool isComplete() const { return _isComplete; }
 
-    const QUuid& getSourceID() const { return _sourceID; }
+    NLPacket::LocalID getSourceID() const { return _sourceID; }
     const HifiSockAddr& getSenderSockAddr() { return _senderSockAddr; }
 
     qint64 getPosition() const { return _position; }
@@ -93,7 +93,7 @@ private:
     std::atomic<qint64> _position { 0 };
     std::atomic<qint64> _numPackets { 0 };
 
-    QUuid _sourceID;
+    NLPacket::LocalID _sourceID { NLPacket::NULL_LOCAL_ID };
     PacketType _packetType;
     PacketVersion _packetVersion;
     HifiSockAddr _senderSockAddr;
diff --git a/libraries/networking/src/SequenceNumberStats.cpp b/libraries/networking/src/SequenceNumberStats.cpp
index 7f1ee39554..e11fcf22d4 100644
--- a/libraries/networking/src/SequenceNumberStats.cpp
+++ b/libraries/networking/src/SequenceNumberStats.cpp
@@ -25,7 +25,7 @@ SequenceNumberStats::SequenceNumberStats(int statsHistoryLength, bool canDetectO
     : _lastReceivedSequence(0),
     _missingSet(),
     _stats(),
-    _lastSenderUUID(),
+    _lastSenderID(NULL_LOCAL_ID),
     _statsHistory(statsHistoryLength),
     _lastUnreasonableSequence(0),
     _consecutiveUnreasonableOnTime(0)
@@ -35,7 +35,7 @@ SequenceNumberStats::SequenceNumberStats(int statsHistoryLength, bool canDetectO
 void SequenceNumberStats::reset() {
     _missingSet.clear();
     _stats = PacketStreamStats();
-    _lastSenderUUID = QUuid();
+    _lastSenderID = NULL_LOCAL_ID;
     _statsHistory.clear();
     _lastUnreasonableSequence = 0;
     _consecutiveUnreasonableOnTime = 0;
@@ -43,18 +43,18 @@ void SequenceNumberStats::reset() {
 
 static const int UINT16_RANGE = std::numeric_limits<uint16_t>::max() + 1;
 
-SequenceNumberStats::ArrivalInfo SequenceNumberStats::sequenceNumberReceived(quint16 incoming, QUuid senderUUID, const bool wantExtraDebugging) {
+SequenceNumberStats::ArrivalInfo SequenceNumberStats::sequenceNumberReceived(quint16 incoming, NetworkLocalID senderID, const bool wantExtraDebugging) {
 
     SequenceNumberStats::ArrivalInfo arrivalInfo;
 
     // if the sender node has changed, reset all stats
-    if (senderUUID != _lastSenderUUID) {
+    if (senderID != _lastSenderID) {
         if (_stats._received > 0) {
             qCDebug(networking) << "sequence number stats was reset due to new sender node";
-            qCDebug(networking) << "previous:" << _lastSenderUUID << "current:" << senderUUID;
+            qCDebug(networking) << "previous:" << _lastSenderID << "current:" << senderID;
             reset();
         }
-        _lastSenderUUID = senderUUID;
+        _lastSenderID = senderID;
     }
 
     // determine our expected sequence number... handle rollover appropriately
diff --git a/libraries/networking/src/SequenceNumberStats.h b/libraries/networking/src/SequenceNumberStats.h
index 46149d4307..8705f960b7 100644
--- a/libraries/networking/src/SequenceNumberStats.h
+++ b/libraries/networking/src/SequenceNumberStats.h
@@ -14,7 +14,7 @@
 
 #include "SharedUtil.h"
 #include "RingBufferHistory.h"
-#include <quuid.h>
+#include "UUID.h"
 
 const int MAX_REASONABLE_SEQUENCE_GAP = 1000;
 
@@ -73,7 +73,7 @@ public:
     SequenceNumberStats(int statsHistoryLength = 0, bool canDetectOutOfSync = true);
 
     void reset();
-    ArrivalInfo sequenceNumberReceived(quint16 incoming, QUuid senderUUID = QUuid(), const bool wantExtraDebugging = false);
+    ArrivalInfo sequenceNumberReceived(quint16 incoming, NetworkLocalID senderID = NULL_LOCAL_ID, const bool wantExtraDebugging = false);
     void pruneMissingSet(const bool wantExtraDebugging = false);
     void pushStatsToHistory() { _statsHistory.insert(_stats); }
 
@@ -100,7 +100,8 @@ private:
 
     PacketStreamStats _stats;
 
-    QUuid _lastSenderUUID;
+    NetworkLocalID _lastSenderID;
+    static const NetworkLocalID NULL_LOCAL_ID = (NetworkLocalID) 0;
 
     RingBufferHistory<PacketStreamStats> _statsHistory;
 
diff --git a/libraries/networking/src/udt/PacketHeaders.cpp b/libraries/networking/src/udt/PacketHeaders.cpp
index 765f01db0e..db466a0403 100644
--- a/libraries/networking/src/udt/PacketHeaders.cpp
+++ b/libraries/networking/src/udt/PacketHeaders.cpp
@@ -91,7 +91,7 @@ PacketVersion versionForPacketType(PacketType packetType) {
         case PacketType::Ping:
             return static_cast<PacketVersion>(PingVersion::IncludeConnectionID);
         default:
-            return 18;
+            return 19;
     }
 }
 
diff --git a/libraries/octree/src/OctreeProcessor.cpp b/libraries/octree/src/OctreeProcessor.cpp
index 0808e817ed..43019c7acc 100644
--- a/libraries/octree/src/OctreeProcessor.cpp
+++ b/libraries/octree/src/OctreeProcessor.cpp
@@ -96,7 +96,7 @@ void OctreeProcessor::processDatagram(ReceivedMessage& message, SharedNodePointe
         quint64 totalUncompress = 0;
         quint64 totalReadBitsteam = 0;
 
-        const QUuid& sourceUUID = message.getSourceID();
+        const QUuid& sourceUUID = sourceNode->getUUID();
         
         int subsection = 1;
         
diff --git a/libraries/shared/src/UUID.h b/libraries/shared/src/UUID.h
index 7e7048486f..55ac0866ee 100644
--- a/libraries/shared/src/UUID.h
+++ b/libraries/shared/src/UUID.h
@@ -15,6 +15,7 @@
 #include <QtCore/QUuid>
 
 const int NUM_BYTES_RFC4122_UUID = 16;
+using NetworkLocalID = quint16;
 
 QString uuidStringWithoutCurlyBraces(const QUuid& uuid);