ack-recons.h

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/*
 * Copyright (c) 1996-1997 The Regents of the University of California.
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 *  This product includes software developed by the Daedalus 
 *      Research Group at the University of California, Berkeley.
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 *
 * ack-recons.cc: contributed by the Daedalus Research Group, 
 * UC Berkeley (http://daedalus.cs.berkeley.edu).
 *
 * $Header: /nfs/jade/vint/CVSROOT/ns-2/tcp/ack-recons.h,v 1.4 2000/09/01 03:04:05 haoboy Exp $
 */

/*
 * TCP Ack reconstructor.  This object sits on the other end of a constrained 
 * link and intersperses TCP acks to the source (without violating the e2e 
 * semantics of TCP acks).  This allows us to get good performance for TCP 
 * over various asymmetric networks, in conjunction with techniques to reduce 
 * the frequency of acks (such as ack filtering) with making any changes to 
 * the TCP source (e.g., like those implemented in tcp-asym.cc).  
 */

#ifndef ns_ack_recons_h
#define ns_ack_recons_h

#include "semantic-packetqueue.h"

class AckReconsController : public TclObject {
public:
    AckReconsController() : spq_(0) {}
    void recv(Packet *p, Handler *h=0);
    SemanticPacketQueue *spq_;
};
    
class AckRecons : public Agent {
public:
    AckRecons(nsaddr_t src, nsaddr_t dst) :
        Agent(PT_TCP), spq_(0), src_(src), dst_(dst),
        ackTemplate_(0), ackPending_(0), lastAck_(0), 
        lastRealAck_(0) {
            bind("lastTime_", &lastTime_);
            bind("lastAck_", &lastAck_);
            bind("lastRealTime_", &lastRealTime_);
            bind("lastRealAck_", &lastRealAck_);
            bind("ackInterArr_", &ackInterArr_);
            bind("ackSpacing_", &ackSpacing_);
            bind("deltaAckThresh_", &deltaAckThresh_);
            bind("delack_", &delack_);
            bind("adaptive_", &adaptive_);
            bind("alpha_", &alpha_);
            bind("size_", &size_);
        }
    int command(int argc, const char*const* argv);
    void handle(Event *e);
    void recv(Packet *p);
    SemanticPacketQueue *spq_; /* the corresponding queue of packets */
private:
    void sendack(int ack, double t); /* send ack pkt at time t */
    nsaddr_t src_;      /* src addr:port */
    nsaddr_t dst_;      /* dst addr:port */
    Packet  *ackTemplate_;  /* used as a template for generated acks */
    int ackPending_;
    int lastAck_;   /* last ack sent by recons, maybe generated */
    int lastRealAck_;   /* last ack actually received on link */
    double  lastTime_;  /* time when last ack was sent */
    double  lastRealTime_;  /* time when last ack arrived on link */
    int dupacks_;   /* number of dup acks seen so far */
    int size_;      /* TCP packet size -- needed because TCP
                 * acks are in terms of packets */
    /* knobs/policies */
    int deltaAckThresh_; /* threshold for reconstruction to kick in */
    double  ackInterArr_;   /* estimate of arrival rate of acks */
    double  ackSpacing_;    /* time duration between acks sent by recons */
    int delack_;    /* generate ack at least every delack_ acks */
    int adaptive_;  /* whether to adapt ack bandwidth? */
    double  alpha_; /* used in linear filter for ack rate est. */
};

#endif

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