--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/internet/model/tcp-newreno.cc Fri Feb 25 10:32:35 2011 -0800
@@ -0,0 +1,236 @@
+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2010 Adrian Sai-wah Tam
+ *
+ * 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: Adrian Sai-wah Tam <adrian.sw.tam@gmail.com>
+ */
+
+#define NS_LOG_APPEND_CONTEXT \
+ if (m_node) { std::clog << Simulator::Now ().GetSeconds () << " [node " << m_node->GetId () << "] "; }
+
+#include "tcp-newreno.h"
+#include "ns3/log.h"
+#include "ns3/trace-source-accessor.h"
+#include "ns3/simulator.h"
+#include "ns3/abort.h"
+#include "ns3/node.h"
+
+NS_LOG_COMPONENT_DEFINE ("TcpNewReno");
+
+namespace ns3 {
+
+NS_OBJECT_ENSURE_REGISTERED (TcpNewReno);
+
+TypeId
+TcpNewReno::GetTypeId (void)
+{
+ static TypeId tid = TypeId ("ns3::TcpNewReno")
+ .SetParent<TcpSocketBase> ()
+ .AddConstructor<TcpNewReno> ()
+ .AddTraceSource ("CongestionWindow",
+ "The TCP connection's congestion window",
+ MakeTraceSourceAccessor (&TcpNewReno::m_cWnd))
+ ;
+ return tid;
+}
+
+TcpNewReno::TcpNewReno (void) : m_inFastRec (false)
+{
+ NS_LOG_FUNCTION (this);
+}
+
+TcpNewReno::TcpNewReno (const TcpNewReno& sock)
+ : TcpSocketBase (sock),
+ m_cWnd (sock.m_cWnd),
+ m_ssThresh (sock.m_ssThresh),
+ m_initialCWnd (sock.m_initialCWnd),
+ m_inFastRec (false)
+{
+ NS_LOG_FUNCTION (this);
+ NS_LOG_LOGIC ("Invoked the copy constructor");
+}
+
+TcpNewReno::~TcpNewReno (void)
+{
+}
+
+/** We initialize m_cWnd from this function, after attributes initialized */
+int
+TcpNewReno::Listen (void)
+{
+ NS_LOG_FUNCTION (this);
+ InitializeCwnd ();
+ return TcpSocketBase::Listen ();
+}
+
+/** We initialize m_cWnd from this function, after attributes initialized */
+int
+TcpNewReno::Connect (const Address & address)
+{
+ NS_LOG_FUNCTION (this << address);
+ InitializeCwnd ();
+ return TcpSocketBase::Connect (address);
+}
+
+/** Limit the size of in-flight data by cwnd and receiver's rxwin */
+uint32_t
+TcpNewReno::Window (void)
+{
+ NS_LOG_FUNCTION (this);
+ return std::min (m_rWnd.Get (), m_cWnd.Get ());
+}
+
+Ptr<TcpSocketBase>
+TcpNewReno::Fork (void)
+{
+ return CopyObject<TcpNewReno> (this);
+}
+
+/** New ACK (up to seqnum seq) received. Increase cwnd and call TcpSocketBase::NewAck() */
+void
+TcpNewReno::NewAck (const SequenceNumber32& seq)
+{
+ NS_LOG_FUNCTION (this << seq);
+ NS_LOG_LOGIC ("TcpNewReno receieved ACK for seq " << seq <<
+ " cwnd " << m_cWnd <<
+ " ssthresh " << m_ssThresh);
+
+ // Check for exit condition of fast recovery
+ if (m_inFastRec && seq < m_recover)
+ { // Partial ACK, partial window deflation (RFC2582 sec.3 bullet #5 paragraph 3)
+ m_cWnd += m_segmentSize; // increase cwnd
+ NS_LOG_INFO ("Partial ACK in fast recovery: cwnd set to " << m_cWnd);
+ TcpSocketBase::NewAck(seq); // update m_nextTxSequence and send new data if allowed by window
+ DoRetransmit (); // Assume the next seq is lost. Retransmit lost packet
+ return;
+ }
+ else if (m_inFastRec && seq >= m_recover)
+ { // Full ACK (RFC2582 sec.3 bullet #5 paragraph 2, option 1)
+ m_cWnd = std::min (m_ssThresh, BytesInFlight () + m_segmentSize);
+ m_inFastRec = false;
+ NS_LOG_INFO ("Received full ACK. Leaving fast recovery with cwnd set to " << m_cWnd);
+ }
+
+ // Increase of cwnd based on current phase (slow start or congestion avoidance)
+ if (m_cWnd < m_ssThresh)
+ { // Slow start mode, add one segSize to cWnd. Default m_ssThresh is 65535. (RFC2001, sec.1)
+ m_cWnd += m_segmentSize;
+ NS_LOG_INFO ("In SlowStart, updated to cwnd " << m_cWnd << " ssthresh " << m_ssThresh);
+ }
+ else
+ { // Congestion avoidance mode, increase by (segSize*segSize)/cwnd. (RFC2581, sec.3.1)
+ // To increase cwnd for one segSize per RTT, it should be (ackBytes*segSize)/cwnd
+ double adder = static_cast<double> (m_segmentSize * m_segmentSize) / m_cWnd.Get ();
+ adder = std::max (1.0, adder);
+ m_cWnd += static_cast<uint32_t> (adder);
+ NS_LOG_INFO ("In CongAvoid, updated to cwnd " << m_cWnd << " ssthresh " << m_ssThresh);
+ }
+
+ // Complete newAck processing
+ TcpSocketBase::NewAck (seq);
+}
+
+/** Cut cwnd and enter fast recovery mode upon triple dupack */
+void
+TcpNewReno::DupAck (const TcpHeader& t, uint32_t count)
+{
+ if (count == 3 && ! m_inFastRec)
+ { // triple duplicate ack triggers fast retransmit (RFC2582 sec.3 bullet #1)
+ m_ssThresh = std::max (2 * m_segmentSize, BytesInFlight () / 2);
+ m_cWnd = m_ssThresh + 3 * m_segmentSize;
+ m_recover = m_highTxMark;
+ m_inFastRec = true;
+ NS_LOG_INFO ("Triple dupack. Enter fast recovery mode. Reset cwnd to " << m_cWnd <<
+ ", ssthresh to " << m_ssThresh << " at fast recovery seqnum " << m_recover);
+ DoRetransmit ();
+ }
+ else if (m_inFastRec)
+ { // Increase cwnd for every additional dupack (RFC2582, sec.3 bullet #3)
+ m_cWnd += m_segmentSize;
+ NS_LOG_INFO ("Dupack in fast recovery mode. Increase cwnd to " << m_cWnd);
+ SendPendingData (m_connected);
+ };
+}
+
+/** Retransmit timeout */
+void
+TcpNewReno::Retransmit (void)
+{
+ NS_LOG_FUNCTION (this);
+ NS_LOG_LOGIC (this << " ReTxTimeout Expired at time " << Simulator::Now ().GetSeconds ());
+ m_inFastRec = false;
+
+ // If erroneous timeout in closed/timed-wait state, just return
+ if (m_state == CLOSED || m_state == TIME_WAIT) return;
+ // If all data are received, just return
+ if (m_txBuffer.HeadSequence () >= m_nextTxSequence) return;
+
+ // According to RFC2581 sec.3.1, upon RTO, ssthresh is set to half of flight
+ // size and cwnd is set to 1*MSS, then the lost packet is retransmitted and
+ // TCP back to slow start
+ m_ssThresh = std::max (2 * m_segmentSize, BytesInFlight () / 2);
+ m_cWnd = m_segmentSize;
+ m_nextTxSequence = m_txBuffer.HeadSequence (); // Restart from highest Ack
+ NS_LOG_INFO ("RTO. Reset cwnd to " << m_cWnd <<
+ ", ssthresh to " << m_ssThresh << ", restart from seqnum " << m_nextTxSequence);
+ m_rtt->IncreaseMultiplier (); // Double the next RTO
+ DoRetransmit (); // Retransmit the packet
+}
+
+void
+TcpNewReno::SetSegSize (uint32_t size)
+{
+ NS_ABORT_MSG_UNLESS (m_state == CLOSED, "TcpNewReno::SetSegSize() cannot change segment size after connection started.");
+ m_segmentSize = size;
+}
+
+void
+TcpNewReno::SetSSThresh (uint32_t threshold)
+{
+ m_ssThresh = threshold;
+}
+
+uint32_t
+TcpNewReno::GetSSThresh (void) const
+{
+ return m_ssThresh;
+}
+
+void
+TcpNewReno::SetInitialCwnd (uint32_t cwnd)
+{
+ NS_ABORT_MSG_UNLESS (m_state == CLOSED, "TcpNewReno::SetInitialCwnd() cannot change initial cwnd after connection started.");
+ m_initialCWnd = cwnd;
+}
+
+uint32_t
+TcpNewReno::GetInitialCwnd (void) const
+{
+ return m_initialCWnd;
+}
+
+void
+TcpNewReno::InitializeCwnd (void)
+{
+ /*
+ * Initialize congestion window, default to 1 MSS (RFC2001, sec.1) and must
+ * not be larger than 2 MSS (RFC2581, sec.3.1). Both m_initiaCWnd and
+ * m_segmentSize are set by the attribute system in ns3::TcpSocket.
+ */
+ m_cWnd = m_initialCWnd * m_segmentSize;
+}
+
+} // namespace ns3