1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
2 /*
3  * Copyright (c) 2016 NITK Surathkal
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  * Authors: Charitha Sangaraju <charitha29193@gmail.com>
19  *          Nandita G <gm.nandita@gmail.com>
20  *          Mohit P. Tahiliani <tahiliani@nitk.edu.in>
21  *
22  */
23 
24 #ifndef TCPLP_H
25 #define TCPLP_H
26 
27 #include "tcp-congestion-ops.h"
28 
29 #include "ns3/traced-value.h"
30 
31 namespace ns3 {
32 
33 class TcpSocketState;
34 
35 class TcpLp : public TcpNewReno
36 {
37 public:
38   /**
39    * \brief Get the type ID.
40    *
41    * \return the object TypeId
42    */
43   static TypeId GetTypeId (void);
44 
45   /**
46    * \brief Creates an unbound tcp socket.
47    *
48    */
49   TcpLp (void);
50 
51   /**
52    * \brief Copy constructor
53    *
54    * \param sock the object to copy
55    */
56   TcpLp (const TcpLp& sock);
57 
58   virtual ~TcpLp (void);
59 
60   /**
61    * \brief Timing information on received ACK
62    *
63    * The function is called every time an ACK is received.
64    * It determines the state of TcpLp and adjusts the congestion window accordingly.
65    *
66    * \param tcb internal congestion state
67    * \param segmentsAcked count of segments acked
68    * \param rtt last rtt
69    */
70   virtual void PktsAcked (Ptr<TcpSocketState> tcb, uint32_t segmentsAcked,
71                           const Time& rtt);
72 
73   virtual std::string GetName () const;
74 
75   virtual Ptr<TcpCongestionOps> Fork ();
76 
77 protected:
78   /**
79    * \brief Invokes Congestion Avoidance of TcpNewReno if TcpLp is not within inference.
80    *
81    * \param tcb internal congestion state
82    * \param segmentsAcked count of segments acked
83    */
84   virtual void CongestionAvoidance (Ptr<TcpSocketState> tcb, uint32_t segmentsAcked);
85 
86 private:
87   /**
88    * \brief Describes the state of TcpLp.
89    *
90    */
91   enum State
92   {
93     LP_VALID_OWD = (1 << 1),    /**< Calculated One-Way Delay is valid */
94     LP_WITHIN_THR = (1 << 3),   /**< TcpLp is within Threshold */
95     LP_WITHIN_INF = (1 << 4),   /**< TcpLp is within Inference */
96   };
97 
98   uint32_t            m_flag;       //!<TcpLp state flag
99   uint32_t            m_sOwd;       //!<Smoothed One-Way Delay
100   uint32_t            m_owdMin;     //!<Minimum One-Way Delay
101   uint32_t            m_owdMax;     //!<Maximum One-Way Delay
102   uint32_t            m_owdMaxRsv;  //!<Reserved Maximum One-Way Delay
103   Time                m_lastDrop;   //!<Last time when cwnd was reduced
104   Time                m_inference;  //!<Current inference period
105 
106 private:
107   /**
108    * \brief Calculates One-Way Delay using Sender and Receiver timestamps.
109    *
110    * \param tcb internal congestion state
111    * \return One-Way Delay
112    */
113   uint32_t OwdCalculator (Ptr<TcpSocketState> tcb);
114 
115   /**
116    * \brief Estimates minimum and maximum One-Way Delays and calculates the smoothed One-Way Delay.
117    *
118    * \param tcb internal congestion state
119    */
120   void RttSample (Ptr<TcpSocketState> tcb);
121 };
122 
123 } // namespace ns3
124 
125 #endif // TCPLP_H
126