diff --git a/daemon/face/datagram-transport.hpp b/daemon/face/datagram-transport.hpp
index e0e2f58..950a49f 100644
--- a/daemon/face/datagram-transport.hpp
+++ b/daemon/face/datagram-transport.hpp
@@ -178,9 +178,7 @@
 
   NFD_LOG_FACE_TRACE("Received: " << buffer.size() << " bytes from " << m_sender);
 
-  bool isOk = false;
-  Block element;
-  std::tie(isOk, element) = Block::fromBuffer(buffer);
+  auto [isOk, element] = Block::fromBuffer(buffer);
   if (!isOk) {
     NFD_LOG_FACE_WARN("Failed to parse incoming packet from " << m_sender);
     // This packet won't extend the face lifetime
diff --git a/daemon/face/ethernet-channel.cpp b/daemon/face/ethernet-channel.cpp
index fae9af2..2509140 100644
--- a/daemon/face/ethernet-channel.cpp
+++ b/daemon/face/ethernet-channel.cpp
@@ -120,19 +120,15 @@
     return;
   }
 
-  span<const uint8_t> pkt;
-  std::string err;
-  std::tie(pkt, err) = m_pcap.readNextPacket();
-
+  auto [pkt, readErr] = m_pcap.readNextPacket();
   if (pkt.empty()) {
-    NFD_LOG_CHAN_WARN("Read error: " << err);
+    NFD_LOG_CHAN_WARN("Read error: " << readErr);
   }
   else {
-    const ether_header* eh;
-    std::tie(eh, err) = ethernet::checkFrameHeader(pkt, m_localEndpoint->getEthernetAddress(),
-                                                   m_localEndpoint->getEthernetAddress());
+    auto [eh, frameErr] = ethernet::checkFrameHeader(pkt, m_localEndpoint->getEthernetAddress(),
+                                                     m_localEndpoint->getEthernetAddress());
     if (eh == nullptr) {
-      NFD_LOG_CHAN_DEBUG(err);
+      NFD_LOG_CHAN_DEBUG(frameErr);
     }
     else {
       ethernet::Address sender(eh->ether_shost);
diff --git a/daemon/face/ethernet-factory.cpp b/daemon/face/ethernet-factory.cpp
index fec671f..4fea598 100644
--- a/daemon/face/ethernet-factory.cpp
+++ b/daemon/face/ethernet-factory.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2020,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -240,7 +240,7 @@
 {
   BOOST_ASSERT(address.isMulticast());
 
-  auto key = std::make_pair(netif.getName(), address);
+  std::pair key(netif.getName(), address);
   auto found = m_mcastFaces.find(key);
   if (found != m_mcastFaces.end()) {
     return found->second;
@@ -339,7 +339,7 @@
     return nullptr;
   }
 
-  if (face->getId() == face::INVALID_FACEID) {
+  if (face->getId() == INVALID_FACEID) {
     // new face: register with forwarding
     this->addFace(face);
   }
diff --git a/daemon/face/ethernet-transport.cpp b/daemon/face/ethernet-transport.cpp
index 7aac95a..568064b 100644
--- a/daemon/face/ethernet-transport.cpp
+++ b/daemon/face/ethernet-transport.cpp
@@ -168,19 +168,15 @@
     return;
   }
 
-  span<const uint8_t> pkt;
-  std::string err;
-  std::tie(pkt, err) = m_pcap.readNextPacket();
-
+  auto [pkt, readErr] = m_pcap.readNextPacket();
   if (pkt.empty()) {
-    NFD_LOG_FACE_WARN("Read error: " << err);
+    NFD_LOG_FACE_WARN("Read error: " << readErr);
   }
   else {
-    const ether_header* eh;
-    std::tie(eh, err) = ethernet::checkFrameHeader(pkt, m_srcAddress,
-                                                   m_destAddress.isMulticast() ? m_destAddress : m_srcAddress);
+    auto [eh, frameErr] = ethernet::checkFrameHeader(pkt, m_srcAddress,
+                                                     m_destAddress.isMulticast() ? m_destAddress : m_srcAddress);
     if (eh == nullptr) {
-      NFD_LOG_FACE_WARN(err);
+      NFD_LOG_FACE_WARN(frameErr);
     }
     else {
       ethernet::Address sender(eh->ether_shost);
@@ -204,9 +200,7 @@
 {
   NFD_LOG_FACE_TRACE("Received: " << payload.size() << " bytes from " << sender);
 
-  bool isOk = false;
-  Block element;
-  std::tie(isOk, element) = Block::fromBuffer(payload);
+  auto [isOk, element] = Block::fromBuffer(payload);
   if (!isOk) {
     NFD_LOG_FACE_WARN("Failed to parse incoming packet from " << sender);
     // This packet won't extend the face lifetime
diff --git a/daemon/face/face-common.hpp b/daemon/face/face-common.hpp
index 0e6f0bb..039d2fe 100644
--- a/daemon/face/face-common.hpp
+++ b/daemon/face/face-common.hpp
@@ -39,26 +39,28 @@
 class Face;
 class LinkService;
 
-/** \brief Identifies a face.
+/**
+ * \brief Identifies a face.
  */
 using FaceId = uint64_t;
 
-/// indicates an invalid FaceId
-const FaceId INVALID_FACEID = ndn::nfd::INVALID_FACE_ID;
-/// identifies the InternalFace used in management
-const FaceId FACEID_INTERNAL_FACE = 1;
-/// identifies a packet comes from the ContentStore
-const FaceId FACEID_CONTENT_STORE = 254;
-/// identifies the NullFace that drops every packet
-const FaceId FACEID_NULL = 255;
-/// upper bound of reserved FaceIds
-const FaceId FACEID_RESERVED_MAX = 255;
+/// Indicates an invalid FaceId
+constexpr FaceId INVALID_FACEID = ndn::nfd::INVALID_FACE_ID;
+/// Identifies the InternalFace used in management
+constexpr FaceId FACEID_INTERNAL_FACE = 1;
+/// Identifies a packet comes from the ContentStore
+constexpr FaceId FACEID_CONTENT_STORE = 254;
+/// Identifies the NullFace that drops every packet
+constexpr FaceId FACEID_NULL = 255;
+/// Upper bound of reserved FaceIds
+constexpr FaceId FACEID_RESERVED_MAX = 255;
 
-/** \brief Minimum MTU that may be set
+/**
+ * \brief Minimum MTU that may be set.
  *
- *  This is done to ensure the NDNLPv2 fragmentation feature functions properly.
+ * This is done to ensure the NDNLPv2 fragmentation feature functions properly.
  */
-const ssize_t MIN_MTU = 64;
+constexpr ssize_t MIN_MTU = 64;
 
 /** \brief Identifies a remote endpoint on the link.
  *
diff --git a/daemon/face/face-system.cpp b/daemon/face/face-system.cpp
index 79cb436..f86ea25 100644
--- a/daemon/face/face-system.cpp
+++ b/daemon/face/face-system.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2021,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -120,22 +120,19 @@
   }
 
   // process in protocol factories
-  for (const auto& pair : m_factories) {
-    const std::string& sectionName = pair.first;
-    ProtocolFactory* factory = pair.second.get();
-
+  for (const auto& [sectionName, factory] : m_factories) {
     std::set<std::string> oldProvidedSchemes = factory->getProvidedSchemes();
     factory->processConfig(configSection.get_child_optional(sectionName), context);
 
     if (!isDryRun) {
-      for (const std::string& scheme : factory->getProvidedSchemes()) {
-        m_factoryByScheme[scheme] = factory;
+      for (const auto& scheme : factory->getProvidedSchemes()) {
+        m_factoryByScheme[scheme] = factory.get();
         if (oldProvidedSchemes.erase(scheme) == 0) {
           NFD_LOG_TRACE("factory " << sectionName <<
                         " provides " << scheme << " FaceUri scheme");
         }
       }
-      for (const std::string& scheme : oldProvidedSchemes) {
+      for (const auto& scheme : oldProvidedSchemes) {
         m_factoryByScheme.erase(scheme);
         NFD_LOG_TRACE("factory " << sectionName <<
                       " no longer provides " << scheme << " FaceUri scheme");
diff --git a/daemon/face/face.cpp b/daemon/face/face.cpp
index 6422a39..cc606d0 100644
--- a/daemon/face/face.cpp
+++ b/daemon/face/face.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2017,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -34,7 +34,6 @@
   , afterReceiveNack(service->afterReceiveNack)
   , onDroppedInterest(service->onDroppedInterest)
   , afterStateChange(transport->afterStateChange)
-  , m_id(INVALID_FACEID)
   , m_service(std::move(service))
   , m_transport(std::move(transport))
   , m_counters(m_service->getCounters(), m_transport->getCounters())
diff --git a/daemon/face/face.hpp b/daemon/face/face.hpp
index e9731ee..976a959 100644
--- a/daemon/face/face.hpp
+++ b/daemon/face/face.hpp
@@ -202,7 +202,7 @@
   }
 
 private:
-  FaceId m_id;
+  FaceId m_id = INVALID_FACEID;
   unique_ptr<LinkService> m_service;
   unique_ptr<Transport> m_transport;
   FaceCounters m_counters;
diff --git a/daemon/face/generic-link-service.cpp b/daemon/face/generic-link-service.cpp
index 5ed4ac2..a21aec2 100644
--- a/daemon/face/generic-link-service.cpp
+++ b/daemon/face/generic-link-service.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2021,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -312,10 +312,7 @@
       return;
     }
 
-    bool isReassembled = false;
-    Block netPkt;
-    lp::Packet firstPkt;
-    std::tie(isReassembled, netPkt, firstPkt) = m_reassembler.receiveFragment(endpoint, pkt);
+    auto [isReassembled, netPkt, firstPkt] = m_reassembler.receiveFragment(endpoint, pkt);
     if (isReassembled) {
       this->decodeNetPacket(netPkt, firstPkt, endpoint);
     }
diff --git a/daemon/face/generic-link-service.hpp b/daemon/face/generic-link-service.hpp
index 7a86b09..0f589a3 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) 2014-2021,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -310,7 +310,7 @@
   /// number of marked packets in the current incident of congestion
   size_t m_nMarkedSinceInMarkingState;
 
-  friend class LpReliability;
+  friend LpReliability;
 };
 
 inline const GenericLinkService::Options&
diff --git a/daemon/face/internal-face.cpp b/daemon/face/internal-face.cpp
index 764dfd7..a7aa7fb 100644
--- a/daemon/face/internal-face.cpp
+++ b/daemon/face/internal-face.cpp
@@ -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) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -46,7 +46,7 @@
 
   auto clientFace = make_shared<ndn::Face>(clientTransport, getGlobalIoService(), clientKeyChain);
 
-  return std::make_tuple(face, clientFace);
+  return {face, clientFace};
 }
 
 } // namespace face
diff --git a/daemon/face/lp-fragmenter.cpp b/daemon/face/lp-fragmenter.cpp
index 7494ca7..6b1755a 100644
--- a/daemon/face/lp-fragmenter.cpp
+++ b/daemon/face/lp-fragmenter.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -39,18 +39,18 @@
 static_assert(lp::tlv::FragCount < 253, "FragCount TLV-TYPE must fit in 1 octet");
 static_assert(lp::tlv::Fragment < 253, "Fragment TLV-TYPE must fit in 1 octet");
 
-/** \brief maximum overhead on a single fragment,
- *         not counting other NDNLPv2 headers
+/**
+ * \brief Maximum overhead on a single fragment, not counting other NDNLPv2 headers.
  */
-static const size_t MAX_SINGLE_FRAG_OVERHEAD =
+const size_t MAX_SINGLE_FRAG_OVERHEAD =
   1 + 9 + // LpPacket TLV-TYPE and TLV-LENGTH
   1 + 1 + 8 + // Sequence TLV
   1 + 9; // Fragment TLV-TYPE and TLV-LENGTH
 
-/** \brief maximum overhead of adding fragmentation to payload,
- *         not counting other NDNLPv2 headers
+/**
+ * \brief Maximum overhead of adding fragmentation to payload, not counting other NDNLPv2 headers.
  */
-static const size_t MAX_FRAG_OVERHEAD =
+const size_t MAX_FRAG_OVERHEAD =
   1 + 9 + // LpPacket TLV-TYPE and TLV-LENGTH
   1 + 1 + 8 + // Sequence TLV
   1 + 1 + 8 + // FragIndex TLV
@@ -86,18 +86,17 @@
     // fast path: fragmentation not needed
     // To qualify for fast path, the packet must have space for adding a sequence number,
     // because another NDNLPv2 feature may require the sequence number.
-    return std::make_tuple(true, std::vector<lp::Packet>{packet});
+    return {true, {packet}};
   }
 
-  ndn::Buffer::const_iterator netPktBegin, netPktEnd;
-  std::tie(netPktBegin, netPktEnd) = packet.get<lp::FragmentField>();
+  auto [netPktBegin, netPktEnd] = packet.get<lp::FragmentField>();
   size_t netPktSize = std::distance(netPktBegin, netPktEnd);
 
   // compute size of other NDNLPv2 headers to be placed on the first fragment
   size_t firstHeaderSize = 0;
-  const Block& packetWire = packet.wireEncode();
+  const auto& packetWire = packet.wireEncode();
   if (packetWire.type() == lp::tlv::LpPacket) {
-    for (const Block& element : packetWire.elements()) {
+    for (const auto& element : packetWire.elements()) {
       if (element.type() != lp::tlv::Fragment) {
         firstHeaderSize += element.size();
       }
@@ -107,7 +106,7 @@
   // compute payload size
   if (MAX_FRAG_OVERHEAD + firstHeaderSize + 1 > mtu) { // 1-octet fragment
     NFD_LOG_FACE_WARN("fragmentation error, MTU too small for first fragment: DROP");
-    return std::make_tuple(false, std::vector<lp::Packet>{});
+    return {false, {}};
   }
   size_t firstPayloadSize = std::min(netPktSize, mtu - firstHeaderSize - MAX_FRAG_OVERHEAD);
   size_t payloadSize = mtu - MAX_FRAG_OVERHEAD;
@@ -117,7 +116,7 @@
   // compute FragCount
   if (fragCount > m_options.nMaxFragments) {
     NFD_LOG_FACE_WARN("fragmentation error, FragCount over limit: DROP");
-    return std::make_tuple(false, std::vector<lp::Packet>{});
+    return {false, {}};
   }
 
   // populate fragments
@@ -139,7 +138,7 @@
   }
   BOOST_ASSERT(fragIndex == fragCount);
 
-  return std::make_tuple(true, frags);
+  return {true, frags};
 }
 
 std::ostream&
diff --git a/daemon/face/lp-reassembler.cpp b/daemon/face/lp-reassembler.cpp
index 77a7120..a4b255b 100644
--- a/daemon/face/lp-reassembler.cpp
+++ b/daemon/face/lp-reassembler.cpp
@@ -45,8 +45,6 @@
 {
   BOOST_ASSERT(packet.has<lp::FragmentField>());
 
-  static auto FALSE_RETURN = std::make_tuple(false, Block(), lp::Packet());
-
   // read and check FragIndex and FragCount
   uint64_t fragIndex = 0;
   uint64_t fragCount = 1;
@@ -59,12 +57,12 @@
 
   if (fragIndex >= fragCount) {
     NFD_LOG_FACE_WARN("reassembly error, FragIndex>=FragCount: DROP");
-    return FALSE_RETURN;
+    return {false, {}, {}};
   }
 
   if (fragCount > m_options.nMaxFragments) {
     NFD_LOG_FACE_WARN("reassembly error, FragCount over limit: DROP");
-    return FALSE_RETURN;
+    return {false, {}, {}};
   }
 
   // check for fast path
@@ -77,10 +75,11 @@
   // check Sequence and compute message identifier
   if (!packet.has<lp::SequenceField>()) {
     NFD_LOG_FACE_WARN("reassembly error, Sequence missing: DROP");
-    return FALSE_RETURN;
+    return {false, {}, {}};
   }
+
   lp::Sequence messageIdentifier = packet.get<lp::SequenceField>() - fragIndex;
-  Key key = std::make_tuple(remoteEndpoint, messageIdentifier);
+  Key key(remoteEndpoint, messageIdentifier);
 
   // add to PartialPacket
   PartialPacket& pp = m_partialPackets[key];
@@ -92,13 +91,13 @@
   else {
     if (fragCount != pp.fragCount) {
       NFD_LOG_FACE_WARN("reassembly error, FragCount changed: DROP");
-      return FALSE_RETURN;
+      return {false, {}, {}};
     }
   }
 
   if (pp.fragments[fragIndex].has<lp::SequenceField>()) {
     NFD_LOG_FACE_TRACE("fragment already received: DROP");
-    return FALSE_RETURN;
+    return {false, {}, {}};
   }
 
   pp.fragments[fragIndex] = packet;
@@ -109,13 +108,13 @@
     Block reassembled = doReassembly(key);
     lp::Packet firstFrag(std::move(pp.fragments[0]));
     m_partialPackets.erase(key);
-    return std::make_tuple(true, reassembled, firstFrag);
+    return {true, reassembled, firstFrag};
   }
 
   // set drop timer
   pp.dropTimer = getScheduler().schedule(m_options.reassemblyTimeout, [=] { timeoutPartialPacket(key); });
 
-  return FALSE_RETURN;
+  return {false, {}, {}};
 }
 
 Block
@@ -125,20 +124,16 @@
 
   size_t payloadSize = std::accumulate(pp.fragments.begin(), pp.fragments.end(), 0U,
     [&] (size_t sum, const lp::Packet& pkt) -> size_t {
-      ndn::Buffer::const_iterator fragBegin, fragEnd;
-      std::tie(fragBegin, fragEnd) = pkt.get<lp::FragmentField>();
+      auto [fragBegin, fragEnd] = pkt.get<lp::FragmentField>();
       return sum + std::distance(fragBegin, fragEnd);
     });
 
   ndn::Buffer fragBuffer(payloadSize);
   auto it = fragBuffer.begin();
-
   for (const lp::Packet& frag : pp.fragments) {
-    ndn::Buffer::const_iterator fragBegin, fragEnd;
-    std::tie(fragBegin, fragEnd) = frag.get<lp::FragmentField>();
+    auto [fragBegin, fragEnd] = frag.get<lp::FragmentField>();
     it = std::copy(fragBegin, fragEnd, it);
   }
-
   return Block(fragBuffer);
 }
 
diff --git a/daemon/face/lp-reassembler.hpp b/daemon/face/lp-reassembler.hpp
index 95c66ff..59db89b 100644
--- a/daemon/face/lp-reassembler.hpp
+++ b/daemon/face/lp-reassembler.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) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -33,8 +33,9 @@
 namespace nfd {
 namespace face {
 
-/** \brief reassembles fragmented network-layer packets
- *  \sa https://redmine.named-data.net/projects/nfd/wiki/NDNLPv2
+/**
+ * \brief Reassembles fragmented network-layer packets
+ * \sa https://redmine.named-data.net/projects/nfd/wiki/NDNLPv2
  */
 class LpReassembler : noncopyable
 {
@@ -96,7 +97,8 @@
   signal::Signal<LpReassembler, EndpointId, size_t> beforeTimeout;
 
 private:
-  /** \brief holds all fragments of packet until reassembled
+  /**
+   * \brief Holds all fragments of packet until reassembled
    */
   struct PartialPacket
   {
@@ -106,12 +108,13 @@
     scheduler::ScopedEventId dropTimer;
   };
 
-  /** \brief index key for PartialPackets
+  /**
+   * \brief Index key for PartialPackets
    */
-  typedef std::tuple<
+  using Key = std::tuple<
     EndpointId, // remoteEndpoint
     lp::Sequence // message identifier (sequence of the first fragment)
-  > Key;
+  >;
 
   Block
   doReassembly(const Key& key);
diff --git a/daemon/face/lp-reliability.cpp b/daemon/face/lp-reliability.cpp
index 95849b1..b287bc3 100644
--- a/daemon/face/lp-reliability.cpp
+++ b/daemon/face/lp-reliability.cpp
@@ -80,10 +80,7 @@
     lp::Sequence txSeq = assignTxSequence(frag);
 
     // Store LpPacket for future retransmissions
-    unackedFragsIt = m_unackedFrags.emplace_hint(unackedFragsIt,
-                                                 std::piecewise_construct,
-                                                 std::forward_as_tuple(txSeq),
-                                                 std::forward_as_tuple(frag));
+    unackedFragsIt = m_unackedFrags.try_emplace(unackedFragsIt, txSeq, frag);
     unackedFragsIt->second.sendTime = sendTime;
     auto rto = m_rttEst.getEstimatedRto();
     lp::Sequence seq = frag.get<lp::SequenceField>();
@@ -179,7 +176,7 @@
         m_recentRecvSeqs.erase(m_recentRecvSeqsQueue.front());
         m_recentRecvSeqsQueue.pop();
       }
-      m_recentRecvSeqs.emplace(pktSequence, now);
+      m_recentRecvSeqs.try_emplace(pktSequence, now);
       m_recentRecvSeqsQueue.push(pktSequence);
     }
 
@@ -324,13 +321,10 @@
     netPkt->didRetx = true;
 
     // Move fragment to new TxSequence mapping
-    auto newTxFragIt = m_unackedFrags.emplace_hint(
-      m_firstUnackedFrag != m_unackedFrags.end() && m_firstUnackedFrag->first > newTxSeq
-        ? m_firstUnackedFrag
-        : m_unackedFrags.end(),
-      std::piecewise_construct,
-      std::forward_as_tuple(newTxSeq),
-      std::forward_as_tuple(txFrag.pkt));
+    auto hint = m_firstUnackedFrag != m_unackedFrags.end() && m_firstUnackedFrag->first > newTxSeq
+                ? m_firstUnackedFrag
+                : m_unackedFrags.end();
+    auto newTxFragIt = m_unackedFrags.try_emplace(hint, newTxSeq, txFrag.pkt);
     auto& newTxFrag = newTxFragIt->second;
     newTxFrag.retxCount = txFrag.retxCount + 1;
     newTxFrag.netPkt = netPkt;
diff --git a/daemon/face/lp-reliability.hpp b/daemon/face/lp-reliability.hpp
index 4349fca..c83b0bc 100644
--- a/daemon/face/lp-reliability.hpp
+++ b/daemon/face/lp-reliability.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2021,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -39,12 +39,18 @@
 
 class GenericLinkService;
 
-/** \brief provides for reliable sending and receiving of link-layer packets
- *  \sa https://redmine.named-data.net/projects/nfd/wiki/NDNLPv2
+/**
+ * \brief Provides for reliable sending and receiving of link-layer packets
+ * \sa https://redmine.named-data.net/projects/nfd/wiki/NDNLPv2
  */
 class LpReliability : noncopyable
 {
 public:
+  /// TxSequence TLV-TYPE (3 octets) + TLV-LENGTH (1 octet) + lp::Sequence (8 octets)
+  static constexpr size_t RESERVED_HEADER_SPACE = tlv::sizeOfVarNumber(lp::tlv::TxSequence) +
+                                                  tlv::sizeOfVarNumber(sizeof(lp::Sequence)) +
+                                                  sizeof(lp::Sequence);
+
   struct Options
   {
     /** \brief enables link-layer reliability
@@ -110,7 +116,6 @@
   class NetPkt;
   using UnackedFrags = std::map<lp::Sequence, UnackedFrag>;
 
-NFD_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
   /** \brief assign TxSequence number to a fragment
    *  \param frag fragment to assign TxSequence to
    *  \return assigned TxSequence number
@@ -163,7 +168,8 @@
   deleteUnackedFrag(UnackedFrags::iterator fragIt);
 
 NFD_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
-  /** \brief contains a sent fragment that has not been acknowledged and associated data
+  /**
+   * \brief Contains a sent fragment that has not been acknowledged and associated data
    */
   class UnackedFrag
   {
@@ -180,7 +186,8 @@
     shared_ptr<NetPkt> netPkt;
   };
 
-  /** \brief contains a network-layer packet with unacknowledged fragments
+  /**
+   * \brief Contains a network-layer packet with unacknowledged fragments
    */
   class NetPkt
   {
@@ -194,13 +201,6 @@
     bool didRetx;
   };
 
-public:
-  /// TxSequence TLV-TYPE (3 octets) + TLV-LENGTH (1 octet) + lp::Sequence (8 octets)
-  static constexpr size_t RESERVED_HEADER_SPACE = tlv::sizeOfVarNumber(lp::tlv::TxSequence) +
-                                                  tlv::sizeOfVarNumber(sizeof(lp::Sequence)) +
-                                                  sizeof(lp::Sequence);
-
-NFD_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
   Options m_options;
   GenericLinkService* m_linkService;
   UnackedFrags m_unackedFrags;
diff --git a/daemon/face/netdev-bound.cpp b/daemon/face/netdev-bound.cpp
index 124ea3a..b22bf62 100644
--- a/daemon/face/netdev-bound.cpp
+++ b/daemon/face/netdev-bound.cpp
@@ -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) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -46,9 +46,7 @@
   std::vector<Rule> rules;
   if (configSection) {
     int ruleIndex = 0;
-    for (const auto& pair : *configSection) {
-      const std::string& key = pair.first;
-      const ConfigSection& value = pair.second;
+    for (const auto& [key, value] : *configSection) {
       if (key == "rule") {
         rules.push_back(parseRule(ruleIndex++, value));
       }
@@ -94,9 +92,7 @@
 
   bool hasWhitelist = false;
   bool hasBlacklist = false;
-  for (const auto& pair : confRule) {
-    const std::string& key = pair.first;
-    const ConfigSection& value = pair.second;
+  for (const auto& [key, value] : confRule) {
     if (key == "remote") {
       try {
         rule.remotes.emplace_back(value.get_value<std::string>());
diff --git a/daemon/face/protocol-factory.hpp b/daemon/face/protocol-factory.hpp
index 50023cc..fcc0418 100644
--- a/daemon/face/protocol-factory.hpp
+++ b/daemon/face/protocol-factory.hpp
@@ -69,9 +69,11 @@
   static void
   registerType(const std::string& id = PF::getId())
   {
-    Registry& registry = getRegistry();
-    BOOST_ASSERT(registry.count(id) == 0);
-    registry[id] = [] (const CtorParams& p) { return make_unique<PF>(p); };
+    BOOST_ASSERT(!id.empty());
+    auto r = getRegistry().insert_or_assign(id, [] (auto&&... p) {
+      return make_unique<PF>(std::forward<decltype(p)>(p)...);
+    });
+    BOOST_VERIFY(r.second);
   }
 
   /** \brief Create a protocol factory instance
diff --git a/daemon/face/tcp-transport.cpp b/daemon/face/tcp-transport.cpp
index 0da07af..466e2c6 100644
--- a/daemon/face/tcp-transport.cpp
+++ b/daemon/face/tcp-transport.cpp
@@ -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) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -36,16 +36,12 @@
 
 NFD_LOG_MEMBER_INIT_SPECIALIZED(StreamTransport<boost::asio::ip::tcp>, TcpTransport);
 
-time::milliseconds TcpTransport::s_initialReconnectWait = 1_s;
-time::milliseconds TcpTransport::s_maxReconnectWait = 5_min;
-float TcpTransport::s_reconnectWaitMultiplier = 2.0f;
-
 TcpTransport::TcpTransport(protocol::socket&& socket,
                            ndn::nfd::FacePersistency persistency,
                            ndn::nfd::FaceScope faceScope)
   : StreamTransport(std::move(socket))
   , m_remoteEndpoint(m_socket.remote_endpoint())
-  , m_nextReconnectWait(s_initialReconnectWait)
+  , m_nextReconnectWait(INITIAL_RECONNECT_DELAY)
 {
   this->setLocalUri(FaceUri(m_socket.local_endpoint()));
   this->setRemoteUri(FaceUri(m_socket.remote_endpoint()));
@@ -165,7 +161,7 @@
   }
 
   m_reconnectEvent.cancel();
-  m_nextReconnectWait = s_initialReconnectWait;
+  m_nextReconnectWait = INITIAL_RECONNECT_DELAY;
 
   this->setLocalUri(FaceUri(m_socket.local_endpoint()));
   NFD_LOG_FACE_TRACE("TCP connection reestablished");
@@ -182,8 +178,8 @@
 
   // exponentially back off the reconnection timer
   m_nextReconnectWait =
-      std::min(time::duration_cast<time::milliseconds>(m_nextReconnectWait * s_reconnectWaitMultiplier),
-               s_maxReconnectWait);
+      std::min(time::duration_cast<time::milliseconds>(m_nextReconnectWait * RECONNECT_DELAY_MULTIPLIER),
+               MAX_RECONNECT_DELAY);
 
   // do this asynchronously because there could be some callbacks still pending
   getGlobalIoService().post([this] { reconnect(); });
diff --git a/daemon/face/tcp-transport.hpp b/daemon/face/tcp-transport.hpp
index c300eed..950d850 100644
--- a/daemon/face/tcp-transport.hpp
+++ b/daemon/face/tcp-transport.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2021,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -72,17 +72,20 @@
   handleReconnectTimeout();
 
 NFD_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
-  /** \brief how long to wait before the first reconnection attempt after the TCP connection has been severed
+  /**
+   * \brief Delay before the first reconnection attempt after the TCP connection has been severed
    */
-  static time::milliseconds s_initialReconnectWait;
+  static constexpr time::milliseconds INITIAL_RECONNECT_DELAY = 1_s;
 
-  /** \brief maximum amount of time to wait before a reconnection attempt
+  /**
+   * \brief Maximum amount of time to wait before a reconnection attempt
    */
-  static time::milliseconds s_maxReconnectWait;
+  static constexpr time::milliseconds MAX_RECONNECT_DELAY = 5_min;
 
-  /** \brief multiplier for the exponential backoff of the reconnection timer
+  /**
+   * \brief Multiplier for the exponential backoff of the reconnection timer
    */
-  static float s_reconnectWaitMultiplier;
+  static constexpr float RECONNECT_DELAY_MULTIPLIER = 2.0f;
 
 private:
   typename protocol::endpoint m_remoteEndpoint;
diff --git a/daemon/face/transport.hpp b/daemon/face/transport.hpp
index 9b84c99..2725596 100644
--- a/daemon/face/transport.hpp
+++ b/daemon/face/transport.hpp
@@ -86,24 +86,29 @@
   ByteCounter nOutBytes;
 };
 
-/** \brief indicates the transport has no limit on payload size
+/**
+ * \brief Indicates that the transport has no limit on payload size
  */
-const ssize_t MTU_UNLIMITED = -1;
+constexpr ssize_t MTU_UNLIMITED = -1;
 
-/** \brief (for internal use) indicates MTU field is unset
+/**
+ * \brief (for internal use) Indicates that the MTU field is unset
  */
-const ssize_t MTU_INVALID = -2;
+constexpr ssize_t MTU_INVALID = -2;
 
-/** \brief indicates that the transport does not support reading the queue capacity/length
+/**
+ * \brief Indicates that the transport does not support reading the queue capacity/length
  */
-const ssize_t QUEUE_UNSUPPORTED = -1;
+constexpr ssize_t QUEUE_UNSUPPORTED = -1;
 
-/** \brief indicates that the transport was unable to retrieve the queue capacity/length
+/**
+ * \brief Indicates that the transport was unable to retrieve the queue capacity/length
  */
-const ssize_t QUEUE_ERROR = -2;
+constexpr ssize_t QUEUE_ERROR = -2;
 
-/** \brief The lower half of a Face.
- *  \sa Face
+/**
+ * \brief The lower half of a Face.
+ * \sa Face
  */
 class Transport : protected virtual TransportCounters, noncopyable
 {