tfrc.h

Ns2 TCP 协议改进 版本 提高goodput

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/*
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 *    must display the following acknowledgement:
 *	This product includes software developed by the Computer Systems
 *	Engineering Group at Lawrence Berkeley Laboratory.
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 *    to endorse or promote products derived from this software without
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#include "agent.h"
#include "packet.h"
#include "ip.h"
#include "timer-handler.h"
#include "random.h"

#define SMALLFLOAT 0.0000001

/* receiver response */ 

#define DECREASE 1
#define NORMAL 2
#define INCREASE 3

#define MAXSEQ 1073741824   /* Number that curseq_ is set to for */
                                /* "infinite send" (2^30)            */


/* modes of rate change */
#define SLOW_START 1
#define CONG_AVOID 2
#define RATE_DECREASE	 3
#define OUT_OF_SLOW_START 4 

struct hdr_tfrc {

	// RFC 3448 specifies that the data packet include the sequence
	// number, timestamp, and RTT estimate.
	int seqno;		//data sequence number
	double timestamp; 	//time this message was sent
	double rtt;	 	//RTT estimate of sender
	// "rate" is used by one of the experimental algorithms, RBPH.
	double rate;		//sender's current rate
	// In a real implementation, tzero, psize, and fsize
	// would not be in the packet header.
	// They are here for convenience.
	double tzero;	 	//RTO in Umass eqn
	int psize;		//Packet size.
	int fsize;		//The default large packet size for VoIP.  
 	// UrgentFlag is used to request that a loss report be sent
	//  immediately.
	int UrgentFlag;		//Urgent Flag
	// "round_id" is used by PreciseLoss_, a variant for more
	//  precise loss events that is on by default.
	int round_id ; 		//round id.

	static int offset_;	// offset for this header
	inline static int& offset() { 
		return offset_; 
	}
	inline static hdr_tfrc* access(const Packet* p) {
		return (hdr_tfrc*) p->access(offset_);
	}

};

struct hdr_tfrc_ack {

	// RFC 3448 specifies that feedback packets must include the
	// timestamp_echo, timestamp_offset, flost, and 
	// rate_since_last_report. 
	double timestamp_offset;	//offset since we received data packet
	double timestamp_echo;		//timestamp from the last data packet
	double flost;		//frequency of loss indications
	double rate_since_last_report;	//what it says ...
	// Used in optional variants:
	int losses;		// number of losses in last RTT
	double NumFeedback_;	//number of times/RTT feedback is to be sent 
	// Used for statistics-reporting only:
	double true_loss;	// true loss event rate.  
	// Not used:
	int seqno;	 	// not sure yet
	double timestamp;		//time this nack was sent


	static int offset_;		 // offset for this header
	inline static int& offset() { 
		return offset_; 
	}
	inline static hdr_tfrc_ack* access(const Packet* p) {
		return (hdr_tfrc_ack*) p->access(offset_);
	}
};

class TfrcAgent; 

class TfrcSendTimer : public TimerHandler {
public:
		TfrcSendTimer(TfrcAgent *a) : TimerHandler() { a_ = a; }
		virtual void expire(Event *e);
protected:
		TfrcAgent *a_;
};	

class TfrcNoFeedbackTimer : public TimerHandler {
public:
		TfrcNoFeedbackTimer(TfrcAgent *a) : TimerHandler() { a_ = a; }
		virtual void expire(Event *e);
protected:
		TfrcAgent *a_;
}; 

class TfrcAgent : public Agent {
		friend class TfrcSendTimer;
	friend class TfrcNoFeedbackTimer;
public:
	TfrcAgent();
	void recv(Packet*, Handler*);
	void sendpkt();
	void nextpkt();
	int command(int argc, const char*const* argv);
	void start();
	void stop();
	void update_rtt(double tao, double now); 
	void increase_rate(double p);
	void decrease_rate();
	double initial_rate();
	void slowstart();
	void reduce_rate_on_no_feedback();
	void advanceby(int delta); 
	void sendmsg(int nbytes, const char *flags = 0);
protected:
	TfrcSendTimer send_timer_;
	TfrcNoFeedbackTimer NoFeedbacktimer_;
	int SndrType_;          // 0 -> infinite sender, 1 -> need FTP
	int maxseq_;            // max seq produced by the app so far
	int seqno_;             // next seq to be sent 
	int psize_;
	double rate_;		// send rate
	double oldrate_;	// allows rate to be changed gradually
	double delta_;		// allows rate to be changed gradually
	int rate_change_; 	// slow start, cong avoid, decrease ...
	double rcvrate  ; 	// TCP friendly rate based on current RTT 
				//  and recever-provded loss estimate
	double maxrate_;	// prevents sending at more than 2 times the 
				//  rate at which the receiver is _receving_ 
	double ss_maxrate_;	// max rate for during slowstart
 	int printStatus_;	// to print status reports
	int datalimited_;	// to send immediately when a new packet
				//   arrives after a data-limited period
	int oldCode_;		// set to 1 not to use "datalimited_"
				//   parameter.
	double last_pkt_time_;	// time the last data packet was sent
	int maxqueue_;		// max queue from application

	/* "accurate" estimates for formula */
	double rtt_; /*EWMA version*/
	double rttcur_; /*Instantaneous version*/
	double rttvar_;
	double tzero_;
	double sqrtrtt_; /*The mean of the sqrt of the RTT*/

	int ca_; //Enable Sqrt(RTT) based congestion avoidance mode

	/* TCP variables for tracking RTT */
	int t_srtt_; 
	int t_rtt_;
	int t_rttvar_;
	int rttvar_exp_;
	double t_rtxcur_;
	double tcp_tick_;
	int T_SRTT_BITS; 
	int T_RTTVAR_BITS;
	int srtt_init_; 
	int rttvar_init_;
	double rtxcur_init_;
	/* End of TCP variables for tracking RTT */

	int InitRate_;		// initial send rate
	double df_;		// decay factor for accurate RTT estimate
	double last_change_;	// time last change in rate was made
	double ssmult_;		// during slow start, increase rate by this 
				//  factor every rtt
	int bval_;		// value of B for the formula
	double overhead_;	// if > 0, dither outgoing packets 
	TracedInt ndatapack_;	// number of packets sent
	TracedInt ndatabytes_;	// number of bytes sent
	TracedDouble true_loss_rate_;	// true loss event rate,
	int UrgentFlag;		// urgent flag
	int active_;		// have we shut down? 
	int round_id ;		// round id
	int first_pkt_rcvd ;	// first ack received yet?
	int ecn_ ;		// Set to 1 for an ECN-capable connection.
	double minrto_ ;	// for experimental purposes, for a minimum
				//  RTO value (for use in the TCP-friendly
				//  equation).
	double rate_init_;	// Static value for initial rate, in 
				//   packets per RTT.
					// for statistics only

	/* Variants in the TFRC algorithms.  */
        int rate_init_option_;  /* 1 for using static rate_init_ */
                                /* 2 for using RFC 3390 */
	int slow_increase_;	// To use slow increases in the rate during
				//  slow-start.
	int ss_changes_;	// To use changes in the slow-start code
				//  to enable higher initial sending rates.
	/* End of variants.  */

	/* Responses to heavy congestion. */
	int conservative_;	// set to 1 for an experimental, conservative 
				//   response to heavy congestion
	double scmult_;         // self clocking parameter for conservative_
	/* End of responses to heavy congestion.  */

	int heavyrounds_;	// the number of RTTs so far when the
				//  sending rate > 2 * receiving rate
	int maxHeavyRounds_;	// the number of allowed rounds for
				//  sending rate > 2 * receiving rate

	/* VoIP mode, for using small packets. */
	int voip_;		// 1 for voip mode.
	int voip_max_pkt_rate_ ;	// Max pkt rate in pps, for voip mode.
	int fsize_;		// Default size for large TCP packets 
				//  (e.g., 1460 bytes).
	/* end of VoIP mode. */

        int useHeaders_;        /* boolean: Add DCCP/IP header sizes */  
        int headersize_;	// Size for packet headers.

};