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Unified Diff: src/internet-stack/tcp-tahoe.cc

Issue 1702042: New TCP architecture for NS-3
Patch Set: Make some variables into TracedValue (testsuite will be in next patchset) Created 13 years, 6 months ago
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Index: src/internet-stack/tcp-tahoe.cc
===================================================================
new file mode 100644
--- /dev/null
+++ b/src/internet-stack/tcp-tahoe.cc
@@ -0,0 +1,190 @@
+/* -*- 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-tahoe.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 ("TcpTahoe");
+
+namespace ns3 {
+
+NS_OBJECT_ENSURE_REGISTERED (TcpTahoe);
+
+TypeId
+TcpTahoe::GetTypeId (void)
+{
+ static TypeId tid = TypeId ("ns3::TcpTahoe")
+ .SetParent<TcpSocketBase> ()
+ .AddConstructor<TcpTahoe> ()
+ .AddTraceSource ("CongestionWindow",
+ "The TCP connection's congestion window",
+ MakeTraceSourceAccessor (&TcpTahoe::m_cWnd))
+ ;
+ return tid;
+}
+
+TcpTahoe::TcpTahoe (void) : m_initialCWnd (0)
+{
+ NS_LOG_FUNCTION (this);
+}
+
+TcpTahoe::TcpTahoe (const TcpTahoe& sock)
+ : TcpSocketBase (sock),
+ m_cWnd (sock.m_cWnd),
+ m_ssThresh (sock.m_ssThresh),
+ m_initialCWnd (sock.m_initialCWnd)
+{
+ NS_LOG_FUNCTION (this);
+ NS_LOG_LOGIC ("Invoked the copy constructor");
+}
+
+TcpTahoe::~TcpTahoe (void)
+{
+}
+
+void
+TcpTahoe::SetNode (Ptr<Node> node)
+{
+ TcpSocketBase::SetNode (node);
+ /*
+ * 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;
+}
+
+/** Limit the size of in-flight data by cwnd and receiver's rxwin */
+uint32_t
+TcpTahoe::Window (void)
+{
+ NS_LOG_FUNCTION (this);
+ return std::min (m_rWnd.Get (), m_cWnd.Get ());
+}
+
+Ptr<TcpSocketBase>
+TcpTahoe::Fork (void)
+{
+ return CopyObject<TcpTahoe> (this);
+}
+
+/** New ACK (up to seqnum seq) received. Increase cwnd and call TcpSocketBase::NewAck() */
+void
+TcpTahoe::NewAck (SequenceNumber32 const& seq)
+{
+ NS_LOG_FUNCTION (this << seq);
+ NS_LOG_LOGIC ("TcpTahoe receieved ACK for seq " << seq <<
+ " cwnd " << m_cWnd <<
+ " ssthresh " << m_ssThresh);
+ 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);
+ }
+ TcpSocketBase::NewAck (seq); // Complete newAck processing
+}
+
+/** Cut down ssthresh upon triple dupack */
+void
+TcpTahoe::DupAck (const TcpHeader& t, uint32_t count)
+{
+ NS_LOG_FUNCTION (this << "t " << count);
+ if (count == 3)
+ { // triple duplicate ack triggers fast retransmit (RFC2001, sec.3)
+ NS_LOG_INFO ("Triple Dup Ack: old ssthresh " << m_ssThresh << " cwnd " << m_cWnd);
+ // fast retransmit in Tahoe means triggering RTO earlier. Tx is restarted
+ // from the highest ack and run slow start again.
+ // (Fall & Floyd 1996, sec.1)
+ m_ssThresh = std::max (static_cast<unsigned> (m_cWnd / 2), m_segmentSize * 2); // Half ssthresh
+ m_cWnd = m_segmentSize; // Run slow start again
+ m_nextTxSequence = m_txBuffer.HeadSequence (); // Restart from highest Ack
+ NS_LOG_INFO ("Triple Dup Ack: new ssthresh " << m_ssThresh << " cwnd " << m_cWnd);
+ NS_LOG_LOGIC ("Triple Dup Ack: retransmit missing segment at " << Simulator::Now ().GetSeconds ());
+ DoRetransmit ();
+ }
+}
+
+/** Retransmit timeout */
+void TcpTahoe::Retransmit (void)
+{
+ NS_LOG_FUNCTION (this);
+ NS_LOG_LOGIC (this << " ReTxTimeout Expired at time " << Simulator::Now ().GetSeconds ());
+ // 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;
+
+ m_ssThresh = std::max (static_cast<unsigned> (m_cWnd / 2), m_segmentSize * 2); // Half ssthresh
+ m_cWnd = m_segmentSize; // Set cwnd to 1 segSize (RFC2001, sec.2)
+ m_nextTxSequence = m_txBuffer.HeadSequence (); // Restart from highest Ack
+ m_rtt->IncreaseMultiplier (); // Double the next RTO
+ DoRetransmit (); // Retransmit the packet
+}
+
+void
+TcpTahoe::SetSegSize (uint32_t size)
+{
+ NS_ABORT_MSG_UNLESS (m_state == CLOSED, "TcpTahoe::SetSegSize() cannot change segment size after connection started.");
+ m_segmentSize = size;
+ m_cWnd = m_initialCWnd * m_segmentSize;
+}
+
+void
+TcpTahoe::SetSSThresh (uint32_t threshold)
+{
+ m_ssThresh = threshold;
+}
+
+uint32_t
+TcpTahoe::GetSSThresh (void) const
+{
+ return m_ssThresh;
+}
+
+void
+TcpTahoe::SetInitialCwnd (uint32_t cwnd)
+{
+ NS_ABORT_MSG_UNLESS (m_state == CLOSED, "TcpTahoe::SetInitialCwnd() cannot change initial cwnd after connection started.");
+ m_initialCWnd = cwnd;
+ m_cWnd = m_initialCWnd * m_segmentSize;
+}
+
+uint32_t
+TcpTahoe::GetInitialCwnd (void) const
+{
+ return m_initialCWnd;
+}
+
+} // namespace ns3

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