Issue #25 Replacing usage of TCP RTT estimator with a customized version
In the current commit, RTT estimator does not implement Karn's algorithm
and takes into account all RTT samples, including ambiguous samples from
retransmitted Interests.
diff --git a/utils/ndn-rtt-estimator.cc b/utils/ndn-rtt-estimator.cc
new file mode 100644
index 0000000..93193d2
--- /dev/null
+++ b/utils/ndn-rtt-estimator.cc
@@ -0,0 +1,248 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+//
+// Copyright (c) 2006 Georgia Tech Research Corporation
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation;
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+//
+// Author: Rajib Bhattacharjea<raj.b@gatech.edu>
+//
+
+// THIS IS A COPY OF rtt-estimator.cc from internet module with minor modifications
+
+// Ported from:
+// Georgia Tech Network Simulator - Round Trip Time Estimation Class
+// George F. Riley. Georgia Tech, Spring 2002
+
+// Implements several variations of round trip time estimators
+
+#include <iostream>
+
+#include "ndn-rtt-estimator.h"
+#include "ns3/simulator.h"
+#include "ns3/double.h"
+#include "ns3/integer.h"
+#include "ns3/uinteger.h"
+#include "ns3/log.h"
+
+NS_LOG_COMPONENT_DEFINE ("ndn.RttEstimator");
+
+namespace ns3 {
+
+namespace ndn {
+
+NS_OBJECT_ENSURE_REGISTERED (RttEstimator);
+
+TypeId
+RttEstimator::GetTypeId (void)
+{
+ static TypeId tid = TypeId ("ns3::ndn::RttEstimator")
+ .SetParent<Object> ()
+ .AddAttribute ("MaxMultiplier",
+ "Maximum RTO Multiplier",
+ UintegerValue (64),
+ MakeUintegerAccessor (&RttEstimator::m_maxMultiplier),
+ MakeUintegerChecker<uint16_t> ())
+ .AddAttribute ("InitialEstimation",
+ "Initial RTT estimation",
+ TimeValue (Seconds (1.0)),
+ MakeTimeAccessor (&RttEstimator::m_initialEstimatedRtt),
+ MakeTimeChecker ())
+ .AddAttribute ("MinRTO",
+ "Minimum retransmit timeout value",
+ TimeValue (Seconds (0.2)), // RFC2988 says min RTO=1 sec, but Linux uses 200ms. See http://www.postel.org/pipermail/end2end-interest/2004-November/004402.html
+ MakeTimeAccessor (&RttEstimator::SetMinRto,
+ &RttEstimator::GetMinRto),
+ MakeTimeChecker ())
+ .AddAttribute ("MaxRTO",
+ "Maximum retransmit timeout value",
+ TimeValue (Seconds (200.0)),
+ MakeTimeAccessor (&RttEstimator::SetMaxRto,
+ &RttEstimator::GetMaxRto),
+ MakeTimeChecker ())
+ ;
+ return tid;
+}
+
+void
+RttEstimator::SetMinRto (Time minRto)
+{
+ NS_LOG_FUNCTION (this << minRto);
+ m_minRto = minRto;
+}
+Time
+RttEstimator::GetMinRto (void) const
+{
+ return m_minRto;
+}
+
+void
+RttEstimator::SetMaxRto (Time maxRto)
+{
+ NS_LOG_FUNCTION (this << maxRto);
+ m_maxRto = maxRto;
+}
+Time
+RttEstimator::GetMaxRto (void) const
+{
+ return m_maxRto;
+}
+
+void
+RttEstimator::SetCurrentEstimate (Time estimate)
+{
+ NS_LOG_FUNCTION (this << estimate);
+ m_currentEstimatedRtt = estimate;
+}
+Time
+RttEstimator::GetCurrentEstimate (void) const
+{
+ return m_currentEstimatedRtt;
+}
+
+
+//RttHistory methods
+RttHistory::RttHistory (SequenceNumber32 s, uint32_t c, Time t)
+ : seq (s), count (c), time (t), retx (false)
+{
+ NS_LOG_FUNCTION (this);
+}
+
+RttHistory::RttHistory (const RttHistory& h)
+ : seq (h.seq), count (h.count), time (h.time), retx (h.retx)
+{
+ NS_LOG_FUNCTION (this);
+}
+
+// Base class methods
+
+RttEstimator::RttEstimator ()
+ : m_next (1),
+ m_nSamples (0),
+ m_multiplier (1),
+ m_history ()
+{
+ NS_LOG_FUNCTION (this);
+ //note next=1 everywhere since first segment will have sequence 1
+
+ // We need attributes initialized here, not later, so use the
+ // ConstructSelf() technique documented in the manual
+ ObjectBase::ConstructSelf (AttributeConstructionList ());
+ m_currentEstimatedRtt = m_initialEstimatedRtt;
+ NS_LOG_DEBUG ("Initialize m_currentEstimatedRtt to " << m_currentEstimatedRtt.GetSeconds () << " sec.");
+}
+
+RttEstimator::RttEstimator (const RttEstimator& c)
+ : Object (c), m_next (c.m_next),
+ m_maxMultiplier (c.m_maxMultiplier),
+ m_initialEstimatedRtt (c.m_initialEstimatedRtt),
+ m_currentEstimatedRtt (c.m_currentEstimatedRtt), m_minRto (c.m_minRto), m_maxRto (c.m_maxRto),
+ m_nSamples (c.m_nSamples), m_multiplier (c.m_multiplier),
+ m_history (c.m_history)
+{
+ NS_LOG_FUNCTION (this);
+}
+
+RttEstimator::~RttEstimator ()
+{
+ NS_LOG_FUNCTION (this);
+}
+
+void RttEstimator::SentSeq (SequenceNumber32 seq, uint32_t size)
+{
+ NS_LOG_FUNCTION (this << seq << size);
+ // Note that a particular sequence has been sent
+ if (seq == m_next)
+ { // This is the next expected one, just log at end
+ m_history.push_back (RttHistory (seq, size, Simulator::Now () ));
+ m_next = seq + SequenceNumber32 (size); // Update next expected
+ }
+ else
+ { // This is a retransmit, find in list and mark as re-tx
+ for (RttHistory_t::iterator i = m_history.begin (); i != m_history.end (); ++i)
+ {
+ if ((seq >= i->seq) && (seq < (i->seq + SequenceNumber32 (i->count))))
+ { // Found it
+ i->retx = true;
+ // One final test..be sure this re-tx does not extend "next"
+ if ((seq + SequenceNumber32 (size)) > m_next)
+ {
+ m_next = seq + SequenceNumber32 (size);
+ i->count = ((seq + SequenceNumber32 (size)) - i->seq); // And update count in hist
+ }
+ break;
+ }
+ }
+ }
+}
+
+Time RttEstimator::AckSeq (SequenceNumber32 ackSeq)
+{
+ NS_LOG_FUNCTION (this << ackSeq);
+ // An ack has been received, calculate rtt and log this measurement
+ // Note we use a linear search (O(n)) for this since for the common
+ // case the ack'ed packet will be at the head of the list
+ Time m = Seconds (0.0);
+ if (m_history.size () == 0) return (m); // No pending history, just exit
+ RttHistory& h = m_history.front ();
+ if (!h.retx && ackSeq >= (h.seq + SequenceNumber32 (h.count)))
+ { // Ok to use this sample
+ m = Simulator::Now () - h.time; // Elapsed time
+ Measurement (m); // Log the measurement
+ ResetMultiplier (); // Reset multiplier on valid measurement
+ }
+ // Now delete all ack history with seq <= ack
+ while(m_history.size () > 0)
+ {
+ RttHistory& h = m_history.front ();
+ if ((h.seq + SequenceNumber32 (h.count)) > ackSeq) break; // Done removing
+ m_history.pop_front (); // Remove
+ }
+ return m;
+}
+
+void RttEstimator::ClearSent ()
+{
+ NS_LOG_FUNCTION (this);
+ // Clear all history entries
+ m_next = 1;
+ m_history.clear ();
+}
+
+void RttEstimator::IncreaseMultiplier ()
+{
+ NS_LOG_FUNCTION (this);
+ m_multiplier = (m_multiplier*2 < m_maxMultiplier) ? m_multiplier*2 : m_maxMultiplier;
+ NS_LOG_DEBUG ("Multiplier increased to " << m_multiplier);
+}
+
+void RttEstimator::ResetMultiplier ()
+{
+ NS_LOG_FUNCTION (this);
+ m_multiplier = 1;
+}
+
+void RttEstimator::Reset ()
+{
+ NS_LOG_FUNCTION (this);
+ // Reset to initial state
+ m_next = 1;
+ m_currentEstimatedRtt = m_initialEstimatedRtt;
+ m_history.clear (); // Remove all info from the history
+ m_nSamples = 0;
+ ResetMultiplier ();
+}
+
+
+} // namespace ndn
+} // namespace ns3
diff --git a/utils/ndn-rtt-estimator.h b/utils/ndn-rtt-estimator.h
new file mode 100644
index 0000000..6bf6aa8
--- /dev/null
+++ b/utils/ndn-rtt-estimator.h
@@ -0,0 +1,172 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+//
+// Copyright (c) 2006 Georgia Tech Research Corporation
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation;
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+//
+// Author: Rajib Bhattacharjea<raj.b@gatech.edu>
+//
+
+// Georgia Tech Network Simulator - Round Trip Time Estimation Class
+// George F. Riley. Georgia Tech, Spring 2002
+
+// THIS IS A COPY OF rtt-estimator.h from internet module with minor modifications
+
+#ifndef NDN_RTT_ESTIMATOR_H
+#define NDN_RTT_ESTIMATOR_H
+
+#include <deque>
+#include "ns3/sequence-number.h"
+#include "ns3/nstime.h"
+#include "ns3/object.h"
+
+namespace ns3 {
+
+namespace ndn {
+
+/**
+ * \ingroup tcp
+ *
+ * \brief Helper class to store RTT measurements
+ */
+class RttHistory {
+public:
+ RttHistory (SequenceNumber32 s, uint32_t c, Time t);
+ RttHistory (const RttHistory& h); // Copy constructor
+public:
+ SequenceNumber32 seq; // First sequence number in packet sent
+ uint32_t count; // Number of bytes sent
+ Time time; // Time this one was sent
+ bool retx; // True if this has been retransmitted
+};
+
+typedef std::deque<RttHistory> RttHistory_t;
+
+/**
+ * \ingroup tcp
+ *
+ * \brief Base class for all RTT Estimators
+ */
+class RttEstimator : public Object {
+public:
+ static TypeId GetTypeId (void);
+
+ RttEstimator();
+ RttEstimator (const RttEstimator&);
+
+ virtual ~RttEstimator();
+
+ /**
+ * \brief Note that a particular sequence has been sent
+ * \param seq the packet sequence number.
+ * \param size the packet size.
+ */
+ virtual void SentSeq (SequenceNumber32 seq, uint32_t size);
+
+ /**
+ * \brief Note that a particular ack sequence has been received
+ * \param ackSeq the ack sequence number.
+ * \return The measured RTT for this ack.
+ */
+ virtual Time AckSeq (SequenceNumber32 ackSeq);
+
+ /**
+ * \brief Clear all history entries
+ */
+ virtual void ClearSent ();
+
+ /**
+ * \brief Add a new measurement to the estimator. Pure virtual function.
+ * \param t the new RTT measure.
+ */
+ virtual void Measurement (Time t) = 0;
+
+ /**
+ * \brief Returns the estimated RTO. Pure virtual function.
+ * \return the estimated RTO.
+ */
+ virtual Time RetransmitTimeout () = 0;
+
+ virtual Ptr<RttEstimator> Copy () const = 0;
+
+ /**
+ * \brief Increase the estimation multiplier up to MaxMultiplier.
+ */
+ virtual void IncreaseMultiplier ();
+
+ /**
+ * \brief Resets the estimation multiplier to 1.
+ */
+ virtual void ResetMultiplier ();
+
+ /**
+ * \brief Resets the estimation to its initial state.
+ */
+ virtual void Reset ();
+
+ /**
+ * \brief Sets the Minimum RTO.
+ * \param minRto The minimum RTO returned by the estimator.
+ */
+ void SetMinRto (Time minRto);
+
+ /**
+ * \brief Get the Minimum RTO.
+ * \return The minimum RTO returned by the estimator.
+ */
+ Time GetMinRto (void) const;
+
+ /**
+ * \brief Sets the Maximum RTO.
+ * \param minRto The maximum RTO returned by the estimator.
+ */
+ void SetMaxRto (Time maxRto);
+
+ /**
+ * \brief Get the Maximum RTO.
+ * \return The maximum RTO returned by the estimator.
+ */
+ Time GetMaxRto (void) const;
+
+ /**
+ * \brief Sets the current RTT estimate (forcefully).
+ * \param estimate The current RTT estimate.
+ */
+ void SetCurrentEstimate (Time estimate);
+
+ /**
+ * \brief gets the current RTT estimate.
+ * \return The current RTT estimate.
+ */
+ Time GetCurrentEstimate (void) const;
+
+private:
+ SequenceNumber32 m_next; // Next expected sequence to be sent
+ uint16_t m_maxMultiplier;
+ Time m_initialEstimatedRtt;
+
+protected:
+ Time m_currentEstimatedRtt; // Current estimate
+ Time m_minRto; // minimum value of the timeout
+ Time m_maxRto; // maximum value of the timeout
+ uint32_t m_nSamples; // Number of samples
+ uint16_t m_multiplier; // RTO Multiplier
+ RttHistory_t m_history; // List of sent packet
+};
+
+} // namespace ndn
+
+} // namespace ns3
+
+#endif /* RTT_ESTIMATOR_H */
diff --git a/utils/ndn-rtt-mean-deviation.cc b/utils/ndn-rtt-mean-deviation.cc
new file mode 100644
index 0000000..8675479
--- /dev/null
+++ b/utils/ndn-rtt-mean-deviation.cc
@@ -0,0 +1,160 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+//
+// Copyright (c) 2006 Georgia Tech Research Corporation
+// (c) 2013 University of Arizona
+// (c) 2013 University of California, Los Angeles
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation;
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+//
+// Author: Rajib Bhattacharjea<raj.b@gatech.edu>
+// Cheng Yi <yic@email.arizona.edu>
+// Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+//
+
+// Georgia Tech Network Simulator - Round Trip Time Estimation Class
+// George F. Riley. Georgia Tech, Spring 2002
+
+#include "ndn-rtt-mean-deviation.h"
+#include "ns3/simulator.h"
+#include "ns3/double.h"
+#include "ns3/integer.h"
+#include "ns3/uinteger.h"
+#include "ns3/log.h"
+
+NS_LOG_COMPONENT_DEFINE ("ndn.RttMeanDeviation");
+
+namespace ns3 {
+namespace ndn {
+
+//---------------------------------------------------------------------------------
+// A modified version of Mean-Deviation Estimator optimized for NDN packet delivery
+
+NS_OBJECT_ENSURE_REGISTERED (RttMeanDeviation);
+
+TypeId
+RttMeanDeviation::GetTypeId (void)
+{
+ static TypeId tid = TypeId ("ns3::ndn::RttMeanDeviation")
+ .SetParent<RttEstimator> ()
+ .AddConstructor<RttMeanDeviation> ()
+ .AddAttribute ("Gain",
+ "Gain used in estimating the RTT (smoothed RTT), must be 0 < Gain < 1",
+ DoubleValue (0.125),
+ MakeDoubleAccessor (&RttMeanDeviation::m_gain),
+ MakeDoubleChecker<double> ())
+ .AddAttribute ("Gain2",
+ "Gain2 used in estimating the RTT (variance), must be 0 < Gain2 < 1",
+ DoubleValue (0.25),
+ MakeDoubleAccessor (&RttMeanDeviation::m_gain2),
+ MakeDoubleChecker<double> ())
+ ;
+ return tid;
+}
+
+RttMeanDeviation::RttMeanDeviation() :
+ m_variance (0)
+{
+ NS_LOG_FUNCTION (this);
+}
+
+RttMeanDeviation::RttMeanDeviation (const RttMeanDeviation& c)
+ : RttEstimator (c), m_gain (c.m_gain), m_gain2 (c.m_gain2), m_variance (c.m_variance)
+{
+ NS_LOG_FUNCTION (this);
+}
+
+void RttMeanDeviation::Measurement (Time m)
+{
+ NS_LOG_FUNCTION (this << m);
+ if (m_nSamples)
+ { // Not first
+ Time err (m - m_currentEstimatedRtt);
+ double gErr = err.ToDouble (Time::S) * m_gain;
+ m_currentEstimatedRtt += Time::FromDouble (gErr, Time::S);
+ Time difference = Abs (err) - m_variance;
+ NS_LOG_DEBUG ("m_variance += " << Time::FromDouble (difference.ToDouble (Time::S) * m_gain2, Time::S));
+ m_variance += Time::FromDouble (difference.ToDouble (Time::S) * m_gain2, Time::S);
+ }
+ else
+ { // First sample
+ m_currentEstimatedRtt = m; // Set estimate to current
+ //variance = sample / 2; // And variance to current / 2
+ // m_variance = m; // try this why????
+ m_variance = Seconds (m.ToDouble (Time::S) / 2);
+ NS_LOG_DEBUG ("(first sample) m_variance += " << m);
+ }
+ m_nSamples++;
+}
+
+Time RttMeanDeviation::RetransmitTimeout ()
+{
+ NS_LOG_FUNCTION (this);
+
+ double retval = std::min (m_maxRto.ToDouble (Time::S),
+ std::max (m_multiplier*m_minRto.ToDouble (Time::S),
+ m_multiplier*(m_currentEstimatedRtt.ToDouble (Time::S) + 4 * m_variance.ToDouble (Time::S))));
+
+ NS_LOG_DEBUG ("RetransmitTimeout: return " << retval);
+
+ return Seconds (retval);
+}
+
+Ptr<RttEstimator> RttMeanDeviation::Copy () const
+{
+ NS_LOG_FUNCTION (this);
+ return CopyObject<RttMeanDeviation> (this);
+}
+
+void RttMeanDeviation::Reset ()
+{
+ NS_LOG_FUNCTION (this);
+ // Reset to initial state
+ m_variance = Seconds (0);
+ RttEstimator::Reset ();
+}
+
+void RttMeanDeviation::Gain (double g)
+{
+ NS_LOG_FUNCTION (this);
+ NS_ASSERT_MSG( (g > 0) && (g < 1), "RttMeanDeviation: Gain must be less than 1 and greater than 0" );
+ m_gain = g;
+}
+
+Time RttMeanDeviation::AckSeq (SequenceNumber32 ackSeq)
+{
+ NS_LOG_FUNCTION (this << ackSeq);
+ // An ack has been received, calculate rtt and log this measurement
+ // Note we use a linear search (O(n)) for this since for the common
+ // case the ack'ed packet will be at the head of the list
+ Time m = Seconds (0.0);
+ if (m_history.size () == 0) return (m); // No pending history, just exit
+
+ for (RttHistory_t::iterator i = m_history.begin (); i != m_history.end (); ++i)
+ {
+ if (ackSeq == i->seq)
+ { // Found it
+ m = Simulator::Now () - i->time;// Elapsed time
+ Measurement (m); // Log the measurement
+ ResetMultiplier (); // Reset multiplier on valid measurement
+ m_history.erase(i);
+ break;
+ }
+ }
+
+ return m;
+}
+
+} // namespace ndn
+} // namespace ns3
+
diff --git a/utils/ndn-rtt-mean-deviation.h b/utils/ndn-rtt-mean-deviation.h
new file mode 100644
index 0000000..7ceecce
--- /dev/null
+++ b/utils/ndn-rtt-mean-deviation.h
@@ -0,0 +1,70 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+//
+// Copyright (c) 2006 Georgia Tech Research Corporation
+// (c) 2013 University of Arizona
+// (c) 2013 University of California, Los Angeles
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation;
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+//
+// Author: Rajib Bhattacharjea<raj.b@gatech.edu>
+// Cheng Yi <yic@email.arizona.edu>
+// Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+//
+
+// Georgia Tech Network Simulator - Round Trip Time Estimation Class
+// George F. Riley. Georgia Tech, Spring 2002
+
+
+#ifndef NDN_RTT_MEAN_DEVIATION_H
+#define NDN_RTT_MEAN_DEVIATION_H
+
+#include <ns3/ndnSIM/utils/ndn-rtt-estimator.h>
+
+namespace ns3 {
+namespace ndn {
+
+/**
+ * \ingroup ndn
+ *
+ * \brief The modified version of "Mean--Deviation" RTT estimator, as discussed by Van Jacobson that better suits NDN communication model
+ *
+ * This class implements the "Mean--Deviation" RTT estimator, as discussed
+ * by Van Jacobson and Michael J. Karels, in
+ * "Congestion Avoidance and Control", SIGCOMM 88, Appendix A
+ *
+ */
+class RttMeanDeviation : public RttEstimator {
+public:
+ static TypeId GetTypeId (void);
+
+ RttMeanDeviation ();
+ RttMeanDeviation (const RttMeanDeviation&);
+
+ Time AckSeq (SequenceNumber32 ackSeq);
+ void Measurement (Time measure);
+ Time RetransmitTimeout ();
+ Ptr<RttEstimator> Copy () const;
+ void Reset ();
+ void Gain (double g);
+
+private:
+ double m_gain; // Filter gain
+ double m_gain2; // Filter gain
+ Time m_variance; // Current variance
+};
+
+} // namespace ndn
+} // namespace ns3
+
+#endif // NDN_RTT_MEAN_DEVIATION