diff --git a/daemon/face/generic-link-service.cpp b/daemon/face/generic-link-service.cpp
index 1fecdb6..7e32fc7 100644
--- a/daemon/face/generic-link-service.cpp
+++ b/daemon/face/generic-link-service.cpp
@@ -125,6 +125,14 @@
 }
 
 void
+GenericLinkService::assignSequences(std::vector<lp::Packet>& pkts)
+{
+  std::for_each(pkts.begin(), pkts.end(), [this] (lp::Packet& pkt) {
+    pkt.set<lp::SequenceField>(++m_lastSeqNo);
+  });
+}
+
+void
 GenericLinkService::encodeLpFields(const ndn::PacketBase& netPkt, lp::Packet& lpPacket)
 {
   if (m_options.allowLocalFields) {
@@ -200,8 +208,8 @@
     BOOST_ASSERT(!frags.front().has<lp::FragCountField>());
   }
 
-  // Only assign sequences to fragments if packet contains more than 1 fragment
-  if (frags.size() > 1) {
+  // Only assign sequences to fragments if reliability enabled or if packet contains >1 fragment
+  if (m_options.reliabilityOptions.isEnabled || frags.size() > 1) {
     // Assign sequences to all fragments
     this->assignSequences(frags);
   }
@@ -216,18 +224,6 @@
 }
 
 void
-GenericLinkService::assignSequence(lp::Packet& pkt)
-{
-  pkt.set<lp::SequenceField>(++m_lastSeqNo);
-}
-
-void
-GenericLinkService::assignSequences(std::vector<lp::Packet>& pkts)
-{
-  std::for_each(pkts.begin(), pkts.end(), [this] (auto& pkt) { this->assignSequence(pkt); });
-}
-
-void
 GenericLinkService::checkCongestionLevel(lp::Packet& pkt)
 {
   ssize_t sendQueueLength = getTransport()->getSendQueueLength();
@@ -279,7 +275,11 @@
     lp::Packet pkt(packet);
 
     if (m_options.reliabilityOptions.isEnabled) {
-      m_reliability.processIncomingPacket(pkt);
+      if (!m_reliability.processIncomingPacket(pkt)) {
+        NFD_LOG_FACE_TRACE("received duplicate fragment: DROP");
+        ++this->nDuplicateSequence;
+        return;
+      }
     }
 
     if (!pkt.has<lp::FragmentField>()) {
diff --git a/daemon/face/generic-link-service.hpp b/daemon/face/generic-link-service.hpp
index 3137555..e30a3e6 100644
--- a/daemon/face/generic-link-service.hpp
+++ b/daemon/face/generic-link-service.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2019,  Regents of the University of California,
+ * Copyright (c) 2014-2020,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -81,6 +81,10 @@
    */
   PacketCounter nRetxExhausted;
 
+  /** \brief count of LpPackets dropped due to duplicate Sequence numbers
+   */
+  PacketCounter nDuplicateSequence;
+
   /** \brief count of outgoing LpPackets that were marked with congestion marks
    */
   PacketCounter nCongestionMarked;
@@ -199,6 +203,11 @@
   void
   doSendNack(const ndn::lp::Nack& nack, const EndpointId& endpointId) OVERRIDE_WITH_TESTS_ELSE_FINAL;
 
+  /** \brief assign consecutive sequence numbers to LpPackets
+   */
+  void
+  assignSequences(std::vector<lp::Packet>& pkts);
+
 private: // send path
   /** \brief encode link protocol fields from tags onto an outgoing LpPacket
    *  \param netPkt network-layer packet to extract tags from
@@ -215,16 +224,6 @@
   void
   sendNetPacket(lp::Packet&& pkt, const EndpointId& endpointId, bool isInterest);
 
-  /** \brief assign a sequence number to an LpPacket
-   */
-  void
-  assignSequence(lp::Packet& pkt);
-
-  /** \brief assign consecutive sequence numbers to LpPackets
-   */
-  void
-  assignSequences(std::vector<lp::Packet>& pkts);
-
   /** \brief if the send queue is found to be congested, add a congestion mark to the packet
    *         according to CoDel
    *  \sa https://tools.ietf.org/html/rfc8289
diff --git a/daemon/face/lp-reliability.cpp b/daemon/face/lp-reliability.cpp
index e9a4914..21189be 100644
--- a/daemon/face/lp-reliability.cpp
+++ b/daemon/face/lp-reliability.cpp
@@ -73,6 +73,9 @@
   netPkt->unackedFrags.reserve(frags.size());
 
   for (lp::Packet& frag : frags) {
+    // Non-IDLE packets are required to have assigned Sequence numbers with LpReliability enabled
+    BOOST_ASSERT(frag.has<lp::SequenceField>());
+
     // Assign TxSequence number
     lp::Sequence txSeq = assignTxSequence(frag);
 
@@ -83,11 +86,11 @@
                                                  std::forward_as_tuple(frag));
     unackedFragsIt->second.sendTime = sendTime;
     auto rto = m_rttEst.getEstimatedRto();
-    NFD_LOG_FACE_TRACE("transmitting txseq=" << txSeq << ", rto=" <<
+    lp::Sequence seq = frag.get<lp::SequenceField>();
+    NFD_LOG_FACE_TRACE("transmitting seq=" << seq << ", txseq=" << txSeq << ", rto=" <<
                        time::duration_cast<time::milliseconds>(rto).count() << "ms");
     unackedFragsIt->second.rtoTimer = getScheduler().schedule(rto, [=] {
-      NFD_LOG_FACE_TRACE("rto timer expired for txseq=" << txSeq);
-      onLpPacketLost(txSeq);
+      onLpPacketLost(txSeq, true);
     });
     unackedFragsIt->second.netPkt = netPkt;
 
@@ -100,19 +103,20 @@
   }
 }
 
-void
+bool
 LpReliability::processIncomingPacket(const lp::Packet& pkt)
 {
   BOOST_ASSERT(m_options.isEnabled);
 
+  bool isDuplicate = false;
   auto now = time::steady_clock::now();
 
   // Extract and parse Acks
-  for (lp::Sequence ackSeq : pkt.list<lp::AckField>()) {
-    auto fragIt = m_unackedFrags.find(ackSeq);
+  for (lp::Sequence ackTxSeq : pkt.list<lp::AckField>()) {
+    auto fragIt = m_unackedFrags.find(ackTxSeq);
     if (fragIt == m_unackedFrags.end()) {
       // Ignore an Ack for an unknown TxSequence number
-      NFD_LOG_FACE_DEBUG("received ack for unknown txseq=" << ackSeq);
+      NFD_LOG_FACE_DEBUG("received ack for unknown txseq=" << ackTxSeq);
       continue;
     }
     auto& frag = fragIt->second;
@@ -121,17 +125,19 @@
     frag.rtoTimer.cancel();
 
     if (frag.retxCount == 0) {
-      NFD_LOG_FACE_TRACE("received ack for txseq=" << ackSeq << ", retx=0, rtt=" <<
+      NFD_LOG_FACE_TRACE("received ack for seq=" << frag.pkt.get<lp::SequenceField>() << ", txseq=" <<
+                         ackTxSeq << ", retx=0, rtt=" <<
                          time::duration_cast<time::milliseconds>(now - frag.sendTime).count() << "ms");
       // This sequence had no retransmissions, so use it to estimate the RTO
       m_rttEst.addMeasurement(now - frag.sendTime);
     }
     else {
-      NFD_LOG_FACE_TRACE("received ack for txseq=" << ackSeq << ", retx=" << frag.retxCount);
+      NFD_LOG_FACE_TRACE("received ack for seq=" << frag.pkt.get<lp::SequenceField>() << ", txseq=" <<
+                         ackTxSeq << ", retx=" << frag.retxCount);
     }
 
-    // Look for frags with TxSequence numbers < ackSeq (allowing for wraparound) and consider them
-    // lost if a configurable number of Acks containing greater TxSequence numbers have been
+    // Look for frags with TxSequence numbers < ackTxSeq (allowing for wraparound) and consider
+    // them lost if a configurable number of Acks containing greater TxSequence numbers have been
     // received.
     auto lostLpPackets = findLostLpPackets(fragIt);
 
@@ -148,9 +154,8 @@
     // Resend or fail fragments considered lost. Potentially increment the start of the window.
     for (lp::Sequence txSeq : lostLpPackets) {
       if (removedLpPackets.find(txSeq) == removedLpPackets.end()) {
-        NFD_LOG_FACE_TRACE("txseq=" << txSeq << " considered lost from acks for more recent txseqs");
-        auto removedThisTxSeq = onLpPacketLost(txSeq);
-        for (auto removedTxSeq : removedThisTxSeq) {
+        auto removedTxSeqs = onLpPacketLost(txSeq, false);
+        for (auto removedTxSeq : removedTxSeqs) {
           removedLpPackets.insert(removedTxSeq);
         }
       }
@@ -161,8 +166,27 @@
   if (pkt.has<lp::FragmentField>() && pkt.has<lp::TxSequenceField>()) {
     NFD_LOG_FACE_TRACE("queueing ack for remote txseq=" << pkt.get<lp::TxSequenceField>());
     m_ackQueue.push(pkt.get<lp::TxSequenceField>());
+
+    // Check for received frames with duplicate Sequences
+    if (pkt.has<lp::SequenceField>()) {
+      lp::Sequence pktSequence = pkt.get<lp::SequenceField>();
+      isDuplicate = m_recentRecvSeqs.count(pktSequence) > 0;
+      // Check for recent received Sequences to remove
+      auto now = time::steady_clock::now();
+      auto rto = m_rttEst.getEstimatedRto();
+      while (m_recentRecvSeqsQueue.size() > 0 &&
+             now > m_recentRecvSeqs[m_recentRecvSeqsQueue.front()] + rto) {
+        m_recentRecvSeqs.erase(m_recentRecvSeqsQueue.front());
+        m_recentRecvSeqsQueue.pop();
+      }
+      m_recentRecvSeqs.emplace(pktSequence, now);
+      m_recentRecvSeqsQueue.push(pktSequence);
+    }
+
     startIdleAckTimer();
   }
+
+  return !isDuplicate;
 }
 
 void
@@ -179,7 +203,7 @@
   remainingSpace -= pktSize;
 
   while (!m_ackQueue.empty()) {
-    lp::Sequence ackSeq = m_ackQueue.front();
+    lp::Sequence ackTxSeq = m_ackQueue.front();
     // Ack size = Ack TLV-TYPE (3 octets) + TLV-LENGTH (1 octet) + lp::Sequence (8 octets)
     const ssize_t ackSize = tlv::sizeOfVarNumber(lp::tlv::Ack) +
                             tlv::sizeOfVarNumber(sizeof(lp::Sequence)) +
@@ -189,9 +213,9 @@
       break;
     }
 
-    NFD_LOG_FACE_TRACE("piggybacking ack for remote txseq=" << ackSeq);
+    NFD_LOG_FACE_TRACE("piggybacking ack for remote txseq=" << ackTxSeq);
 
-    pkt.add<lp::AckField>(ackSeq);
+    pkt.add<lp::AckField>(ackTxSeq);
     m_ackQueue.pop();
     remainingSpace -= ackSize;
   }
@@ -239,8 +263,8 @@
 
     auto& unackedFrag = it->second;
     unackedFrag.nGreaterSeqAcks++;
-    NFD_LOG_FACE_TRACE("received ack=" << ackIt->first << ", out-of-order for txseq=" <<
-                       it->first << ", out-of-order count=" << unackedFrag.nGreaterSeqAcks);
+    NFD_LOG_FACE_TRACE("received ack=" << ackIt->first << " before=" << it->first <<
+                       ", before count=" << unackedFrag.nGreaterSeqAcks);
 
     if (unackedFrag.nGreaterSeqAcks >= m_options.seqNumLossThreshold) {
       lostLpPackets.push_back(it->first);
@@ -251,7 +275,7 @@
 }
 
 std::vector<lp::Sequence>
-LpReliability::onLpPacketLost(lp::Sequence txSeq)
+LpReliability::onLpPacketLost(lp::Sequence txSeq, bool isTimeout)
 {
   BOOST_ASSERT(m_unackedFrags.count(txSeq) > 0);
   auto txSeqIt = m_unackedFrags.find(txSeq);
@@ -260,10 +284,19 @@
   txFrag.rtoTimer.cancel();
   auto netPkt = txFrag.netPkt;
   std::vector<lp::Sequence> removedThisTxSeq;
+  lp::Sequence seq = txFrag.pkt.get<lp::SequenceField>();
+
+  if (isTimeout) {
+    NFD_LOG_FACE_TRACE("rto timer expired for seq=" << seq << ", txseq=" << txSeq);
+  }
+  else { // lost due to out-of-order TxSeqs
+    NFD_LOG_FACE_TRACE("seq=" << seq << ", txseq=" << txSeq <<
+                       " considered lost from acks for more recent txseqs");
+  }
 
   // Check if maximum number of retransmissions exceeded
   if (txFrag.retxCount >= m_options.maxRetx) {
-    NFD_LOG_FACE_DEBUG("txseq=" << txSeq << " exceeded allowed retransmissions: DROP");
+    NFD_LOG_FACE_DEBUG("seq=" << seq << " exceeded allowed retransmissions: DROP");
     // Delete all LpPackets of NetPkt from m_unackedFrags (except this one)
     for (size_t i = 0; i < netPkt->unackedFrags.size(); i++) {
       if (netPkt->unackedFrags[i] != txSeqIt) {
@@ -316,14 +349,13 @@
     m_linkService->sendLpPacket(lp::Packet(newTxFrag.pkt), 0);
 
     auto rto = m_rttEst.getEstimatedRto();
-    NFD_LOG_FACE_TRACE("retransmitting txseq=" << txSeq << " as " << newTxSeq << ", retx=" <<
+    NFD_LOG_FACE_TRACE("retransmitting seq=" << seq << ", txseq=" << newTxSeq << ", retx=" <<
                        txFrag.retxCount << ", rto=" <<
                        time::duration_cast<time::milliseconds>(rto).count() << "ms");
 
     // Start RTO timer for this sequence
     newTxFrag.rtoTimer = getScheduler().schedule(rto, [=] {
-      NFD_LOG_FACE_TRACE("rto timer expired for txseq=" << newTxSeq);
-      onLpPacketLost(newTxSeq);
+      onLpPacketLost(newTxSeq, true);
     });
   }
 
diff --git a/daemon/face/lp-reliability.hpp b/daemon/face/lp-reliability.hpp
index ad7c968..1ea2b9a 100644
--- a/daemon/face/lp-reliability.hpp
+++ b/daemon/face/lp-reliability.hpp
@@ -93,8 +93,9 @@
 
   /** \brief extract and parse all Acks and add Ack for contained Fragment (if any) to AckQueue
    *  \param pkt incoming LpPacket
+   *  \return whether incoming LpPacket is new and not a duplicate
    */
-  void
+  bool
   processIncomingPacket(const lp::Packet& pkt);
 
   /** \brief called by GenericLinkService to attach Acks onto an outgoing LpPacket
@@ -139,7 +140,7 @@
    *  \return vector of the TxSequences of fragments removed due to a network packet being removed
    */
   std::vector<lp::Sequence>
-  onLpPacketLost(lp::Sequence txSeq);
+  onLpPacketLost(lp::Sequence txSeq, bool isTimeout);
 
   /** \brief remove the fragment with the given sequence number from the map of unacknowledged
    *         fragments, as well as its associated network packet (if any)
@@ -210,6 +211,8 @@
    */
   UnackedFrags::iterator m_firstUnackedFrag;
   std::queue<lp::Sequence> m_ackQueue;
+  std::map<lp::Sequence, time::steady_clock::TimePoint> m_recentRecvSeqs;
+  std::queue<lp::Sequence> m_recentRecvSeqsQueue;
   lp::Sequence m_lastTxSeqNo;
   scheduler::ScopedEventId m_idleAckTimer;
   ndn::util::RttEstimator m_rttEst;