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tcp-newreno.cc
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
2 /*
3  * Copyright (c) 2010 Adrian Sai-wah Tam
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation;
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17  *
18  * Author: Adrian Sai-wah Tam <adrian.sw.tam@gmail.com>
19  */
20 
21 #define NS_LOG_APPEND_CONTEXT \
22  if (m_node) { std::clog << Simulator::Now ().GetSeconds () << " [node " << m_node->GetId () << "] "; }
23 
24 #include "tcp-newreno.h"
25 #include "ns3/log.h"
26 #include "ns3/trace-source-accessor.h"
27 #include "ns3/simulator.h"
28 #include "ns3/abort.h"
29 #include "ns3/node.h"
30 
31 NS_LOG_COMPONENT_DEFINE ("TcpNewReno");
32 
33 namespace ns3 {
34 
35 NS_OBJECT_ENSURE_REGISTERED (TcpNewReno);
36 
37 TypeId
39 {
40  static TypeId tid = TypeId ("ns3::TcpNewReno")
42  .AddConstructor<TcpNewReno> ()
43  .AddAttribute ("ReTxThreshold", "Threshold for fast retransmit",
44  UintegerValue (3),
45  MakeUintegerAccessor (&TcpNewReno::m_retxThresh),
46  MakeUintegerChecker<uint32_t> ())
47  .AddAttribute ("LimitedTransmit", "Enable limited transmit",
48  BooleanValue (false),
49  MakeBooleanAccessor (&TcpNewReno::m_limitedTx),
50  MakeBooleanChecker ())
51  .AddTraceSource ("CongestionWindow",
52  "The TCP connection's congestion window",
54  .AddTraceSource ("SlowStartThreshold",
55  "TCP slow start threshold (bytes)",
57  ;
58  return tid;
59 }
60 
62  : m_retxThresh (3), // mute valgrind, actual value set by the attribute system
63  m_inFastRec (false),
64  m_limitedTx (false) // mute valgrind, actual value set by the attribute system
65 {
66  NS_LOG_FUNCTION (this);
67 }
68 
70  : TcpSocketBase (sock),
71  m_cWnd (sock.m_cWnd),
72  m_ssThresh (sock.m_ssThresh),
73  m_initialCWnd (sock.m_initialCWnd),
74  m_initialSsThresh (sock.m_initialSsThresh),
75  m_retxThresh (sock.m_retxThresh),
76  m_inFastRec (false),
77  m_limitedTx (sock.m_limitedTx)
78 {
79  NS_LOG_FUNCTION (this);
80  NS_LOG_LOGIC ("Invoked the copy constructor");
81 }
82 
84 {
85 }
86 
87 /* We initialize m_cWnd from this function, after attributes initialized */
88 int
90 {
91  NS_LOG_FUNCTION (this);
92  InitializeCwnd ();
93  return TcpSocketBase::Listen ();
94 }
95 
96 /* We initialize m_cWnd from this function, after attributes initialized */
97 int
99 {
100  NS_LOG_FUNCTION (this << address);
101  InitializeCwnd ();
102  return TcpSocketBase::Connect (address);
103 }
104 
105 /* Limit the size of in-flight data by cwnd and receiver's rxwin */
106 uint32_t
108 {
109  NS_LOG_FUNCTION (this);
110  return std::min (m_rWnd.Get (), m_cWnd.Get ());
111 }
112 
115 {
116  return CopyObject<TcpNewReno> (this);
117 }
118 
119 /* New ACK (up to seqnum seq) received. Increase cwnd and call TcpSocketBase::NewAck() */
120 void
122 {
123  NS_LOG_FUNCTION (this << seq);
124  NS_LOG_LOGIC ("TcpNewReno receieved ACK for seq " << seq <<
125  " cwnd " << m_cWnd <<
126  " ssthresh " << m_ssThresh);
127 
128  // Check for exit condition of fast recovery
129  if (m_inFastRec && seq < m_recover)
130  { // Partial ACK, partial window deflation (RFC2582 sec.3 bullet #5 paragraph 3)
132  NS_LOG_INFO ("Partial ACK in fast recovery: cwnd set to " << m_cWnd);
133  m_txBuffer.DiscardUpTo(seq); //Bug 1850: retransmit before newack
134  DoRetransmit (); // Assume the next seq is lost. Retransmit lost packet
135  TcpSocketBase::NewAck (seq); // update m_nextTxSequence and send new data if allowed by window
136  return;
137  }
138  else if (m_inFastRec && seq >= m_recover)
139  { // Full ACK (RFC2582 sec.3 bullet #5 paragraph 2, option 1)
140  m_cWnd = std::min (m_ssThresh.Get (), BytesInFlight () + m_segmentSize);
141  m_inFastRec = false;
142  NS_LOG_INFO ("Received full ACK. Leaving fast recovery with cwnd set to " << m_cWnd);
143  }
144 
145  // Increase of cwnd based on current phase (slow start or congestion avoidance)
146  if (m_cWnd < m_ssThresh)
147  { // Slow start mode, add one segSize to cWnd. Default m_ssThresh is 65535. (RFC2001, sec.1)
149  NS_LOG_INFO ("In SlowStart, updated to cwnd " << m_cWnd << " ssthresh " << m_ssThresh);
150  }
151  else
152  { // Congestion avoidance mode, increase by (segSize*segSize)/cwnd. (RFC2581, sec.3.1)
153  // To increase cwnd for one segSize per RTT, it should be (ackBytes*segSize)/cwnd
154  double adder = static_cast<double> (m_segmentSize * m_segmentSize) / m_cWnd.Get ();
155  adder = std::max (1.0, adder);
156  m_cWnd += static_cast<uint32_t> (adder);
157  NS_LOG_INFO ("In CongAvoid, updated to cwnd " << m_cWnd << " ssthresh " << m_ssThresh);
158  }
159 
160  // Complete newAck processing
161  TcpSocketBase::NewAck (seq);
162 }
163 
164 /* Cut cwnd and enter fast recovery mode upon triple dupack */
165 void
166 TcpNewReno::DupAck (const TcpHeader& t, uint32_t count)
167 {
168  NS_LOG_FUNCTION (this << count);
169  if (count == m_retxThresh && !m_inFastRec)
170  { // triple duplicate ack triggers fast retransmit (RFC2582 sec.3 bullet #1)
171  m_ssThresh = std::max (2 * m_segmentSize, BytesInFlight () / 2);
174  m_inFastRec = true;
175  NS_LOG_INFO ("Triple dupack. Enter fast recovery mode. Reset cwnd to " << m_cWnd <<
176  ", ssthresh to " << m_ssThresh << " at fast recovery seqnum " << m_recover);
177  DoRetransmit ();
178  }
179  else if (m_inFastRec)
180  { // Increase cwnd for every additional dupack (RFC2582, sec.3 bullet #3)
182  NS_LOG_INFO ("Dupack in fast recovery mode. Increase cwnd to " << m_cWnd);
184  }
186  { // RFC3042 Limited transmit: Send a new packet for each duplicated ACK before fast retransmit
187  NS_LOG_INFO ("Limited transmit");
188  uint32_t sz = SendDataPacket (m_nextTxSequence, m_segmentSize, true);
189  m_nextTxSequence += sz; // Advance next tx sequence
190  };
191 }
192 
193 /* Retransmit timeout */
194 void
196 {
197  NS_LOG_FUNCTION (this);
198  NS_LOG_LOGIC (this << " ReTxTimeout Expired at time " << Simulator::Now ().GetSeconds ());
199  m_inFastRec = false;
200 
201  // If erroneous timeout in closed/timed-wait state, just return
202  if (m_state == CLOSED || m_state == TIME_WAIT) return;
203  // If all data are received (non-closing socket and nothing to send), just return
204  if (m_state <= ESTABLISHED && m_txBuffer.HeadSequence () >= m_highTxMark) return;
205 
206  // According to RFC2581 sec.3.1, upon RTO, ssthresh is set to half of flight
207  // size and cwnd is set to 1*MSS, then the lost packet is retransmitted and
208  // TCP back to slow start
209  m_ssThresh = std::max (2 * m_segmentSize, BytesInFlight () / 2);
211  m_nextTxSequence = m_txBuffer.HeadSequence (); // Restart from highest Ack
212  NS_LOG_INFO ("RTO. Reset cwnd to " << m_cWnd <<
213  ", ssthresh to " << m_ssThresh << ", restart from seqnum " << m_nextTxSequence);
214  m_rtt->IncreaseMultiplier (); // Double the next RTO
215  DoRetransmit (); // Retransmit the packet
216 }
217 
218 void
219 TcpNewReno::SetSegSize (uint32_t size)
220 {
221  NS_ABORT_MSG_UNLESS (m_state == CLOSED, "TcpNewReno::SetSegSize() cannot change segment size after connection started.");
222  m_segmentSize = size;
223 }
224 
225 void
226 TcpNewReno::SetInitialSSThresh (uint32_t threshold)
227 {
228  NS_ABORT_MSG_UNLESS (m_state == CLOSED, "TcpNewReno::SetSSThresh() cannot change initial ssThresh after connection started.");
229  m_initialSsThresh = threshold;
230 }
231 
232 uint32_t
234 {
235  return m_initialSsThresh;
236 }
237 
238 void
240 {
241  NS_ABORT_MSG_UNLESS (m_state == CLOSED, "TcpNewReno::SetInitialCwnd() cannot change initial cwnd after connection started.");
242  m_initialCWnd = cwnd;
243 }
244 
245 uint32_t
247 {
248  return m_initialCWnd;
249 }
250 
251 void
253 {
254  /*
255  * Initialize congestion window, default to 1 MSS (RFC2001, sec.1) and must
256  * not be larger than 2 MSS (RFC2581, sec.3.1). Both m_initiaCWnd and
257  * m_segmentSize are set by the attribute system in ns3::TcpSocket.
258  */
261 }
262 
263 } // namespace ns3
virtual int Listen(void)
Listen for incoming connections.
smart pointer class similar to boost::intrusive_ptr
Definition: ptr.h:60
#define NS_LOG_FUNCTION(parameters)
If log level LOG_FUNCTION is enabled, this macro will output all input parameters separated by "...
virtual void NewAck(SequenceNumber32 const &seq)
Update buffers w.r.t.
Definition: tcp-newreno.cc:121
Hold a bool native type.
Definition: boolean.h:38
bool m_limitedTx
perform limited transmit
Definition: tcp-newreno.h:86
uint32_t SendDataPacket(SequenceNumber32 seq, uint32_t maxSize, bool withAck)
Extract at most maxSize bytes from the TxBuffer at sequence seq, add the TCP header, and send to TcpL4Protocol.
void DiscardUpTo(const SequenceNumber32 &seq)
Discard data up to but not including this sequence number.
#define NS_OBJECT_ENSURE_REGISTERED(type)
Register the class in the ns-3 factory.
Definition: object-base.h:38
uint32_t SizeFromSequence(const SequenceNumber32 &seq) const
Returns the number of bytes from the buffer in the range [seq, tailSequence)
SequenceNumber32 HeadSequence(void) const
Returns the first byte's sequence number.
uint32_t m_initialSsThresh
Initial Slow Start Threshold value.
Definition: tcp-newreno.h:82
virtual int Listen(void)
Listen for incoming connections.
Definition: tcp-newreno.cc:89
#define NS_LOG_COMPONENT_DEFINE(name)
Define a Log component with a specific name.
Definition: log.h:170
virtual uint32_t GetInitialCwnd(void) const
Get the initial Congestion Window.
Definition: tcp-newreno.cc:246
virtual uint32_t Window(void)
Return the max possible number of unacked bytes.
Definition: tcp-newreno.cc:107
#define NS_LOG_INFO(msg)
Use NS_LOG to output a message of level LOG_INFO.
Definition: log.h:223
uint32_t m_segmentSize
Segment size.
TracedValue< SequenceNumber32 > m_nextTxSequence
Next seqnum to be sent (SND.NXT), ReTx pushes it back.
An implementation of a stream socket using TCP.
Definition: tcp-newreno.h:36
T Get(void) const
Definition: traced-value.h:99
TracedValue< TcpStates_t > m_state
TCP state.
virtual void SetSegSize(uint32_t size)
Set the segment size.
Definition: tcp-newreno.cc:219
a polymophic address class
Definition: address.h:86
TracedValue< uint32_t > m_ssThresh
Slow Start Threshold.
Definition: tcp-newreno.h:80
TcpTxBuffer m_txBuffer
Tx buffer.
static TypeId GetTypeId(void)
Get the type ID.
Definition: tcp-newreno.cc:38
virtual void DupAck(const TcpHeader &t, uint32_t count)
Received dupack (duplicate ACK)
Definition: tcp-newreno.cc:166
Hold an unsigned integer type.
Definition: uinteger.h:46
virtual void SetInitialCwnd(uint32_t cwnd)
Set the initial Congestion Window.
Definition: tcp-newreno.cc:239
virtual uint32_t GetInitialSSThresh(void) const
Get the initial Slow Start Threshold.
Definition: tcp-newreno.cc:233
virtual int Connect(const Address &address)
Initiate a connection to a remote host.
Definition: tcp-newreno.cc:98
TracedValue< uint32_t > m_cWnd
Congestion window.
Definition: tcp-newreno.h:79
A base class for implementation of a stream socket using TCP.
Ptr< RttEstimator > m_rtt
Round trip time estimator.
void InitializeCwnd(void)
Set the congestion window when connection starts.
Definition: tcp-newreno.cc:252
#define NS_LOG_LOGIC(msg)
Use NS_LOG to output a message of level LOG_LOGIC.
Definition: log.h:233
bool m_inFastRec
currently in fast recovery
Definition: tcp-newreno.h:85
uint32_t m_retxThresh
Fast Retransmit threshold.
Definition: tcp-newreno.h:84
Ptr< const TraceSourceAccessor > MakeTraceSourceAccessor(T a)
Header for the Transmission Control Protocol.
Definition: tcp-header.h:44
virtual uint32_t BytesInFlight(void)
Return total bytes in flight.
virtual int Connect(const Address &address)
Initiate a connection to a remote host.
virtual void Retransmit(void)
Halving cwnd and call DoRetransmit()
Definition: tcp-newreno.cc:195
static Time Now(void)
Return the "current simulation time".
Definition: simulator.cc:180
TracedValue< SequenceNumber32 > m_highTxMark
Highest seqno ever sent, regardless of ReTx.
uint32_t m_initialCWnd
Initial cWnd value.
Definition: tcp-newreno.h:81
virtual void NewAck(SequenceNumber32 const &seq)
Update buffers w.r.t.
bool m_connected
Connection established.
#define NS_ABORT_MSG_UNLESS(cond, msg)
Abnormal program termination if cond is false.
Definition: abort.h:136
virtual Ptr< TcpSocketBase > Fork(void)
Call CopyObject<> to clone me.
Definition: tcp-newreno.cc:114
tuple address
Definition: first.py:37
TcpNewReno(void)
Create an unbound tcp socket.
Definition: tcp-newreno.cc:61
a unique identifier for an interface.
Definition: type-id.h:49
virtual void SetInitialSSThresh(uint32_t threshold)
Set the initial Slow Start Threshold.
Definition: tcp-newreno.cc:226
TypeId SetParent(TypeId tid)
Definition: type-id.cc:610
bool SendPendingData(bool withAck=false)
Send as much pending data as possible according to the Tx window.
TracedValue< uint32_t > m_rWnd
Flow control window at remote side.
virtual void DoRetransmit(void)
Retransmit the oldest packet.
SequenceNumber32 m_recover
Previous highest Tx seqnum for fast recovery.
Definition: tcp-newreno.h:83
virtual ~TcpNewReno(void)
Definition: tcp-newreno.cc:83