drcl.inet.transport
Class TCP

java.lang.Object
  |
  +--drcl.DrclObj
        |
        +--drcl.comp.Component
              |
              +--drcl.net.Module
                    |
                    +--drcl.inet.Protocol
                          |
                          +--drcl.inet.transport.TCP

All Implemented Interfaces:

ActiveComponent, java.lang.Cloneable, drcl.inet.transport.Connection, InetConstants, ObjectDuplicable, java.io.Serializable, TCPConstants

Direct Known Subclasses:

TCPb

public class TCP

extends Protocol

implements TCPConstants, drcl.inet.transport.Connection, ActiveComponent

This component implements the single-session sender TCP. Since only one session is handled in this component, open and close of the connection is not implemented, nor is the 3-way handshaking.

Several variants of TCP are implemented: Tahoe, Reno, New-Reno ([Fall96]) and Vegas ([Brakmo95]). Each can be used with the SACK option. Currently only New-Reno takes advantage of the SACK blocks in an ACK. To specify which implementation, use setImplementation(String) with "Tahoe", "Reno", "New-Reno" or "Vegas" as argument. To enable SACK, use setSackEnabled(boolean).

The initial sequence number is set as 0, instead of a random value suggestted in [TCPILL2]

For Tahoe and Reno, the RTT and RXT timer base estimation is based on [TCPILL2]. The sending time of a segment is recorded as ts_ in the TCP header (similar to the timestamp option in the real TCP header) and returned by the corresponding acknowledgment packet. ts_ is set to -1 if the segment is a retransmitted one, so no RTT estimation is performed for retransmitted segments. The algorithm is described in [RFC793] and [TCPILL1].

SampleRTT = current time - ts_;
SmoothedRTT[new] = 7/8*SmoothedRTT[old] + 1/8*SampleRTT;
Delta = |SampleRTT - SmoothedRTT[old]|;
RTTVariance[new] = 3/4*RTTVariance[old] + 1/4*Delta;
and the retransmission timer base is 
RTO[new] = SmoothedRTT[new] + 4*RTTVariance[new].

The exception is that for the first acknowledgment received:

SampleRTT = current time - ts_;
SmoothedRTT[new] = SampleRTT;
RTTVariance[new] = SampleRTT/2;
and the retransmission timer base is 
RTO[new] = SmoothedRTT[new] + 4*RTTVariance[new].

Additional usage infomation:

1. The "maxburst" option, use setMaxburstEnabled(boolean). This option restricts the maximum number of bytes that can be sent in response to a single ACK to be one segment during Reno-style fast recovery, and two segments otherwise. This is based on [RFC2018] and is different from similar setting in [Fall96]. For Vegas, only two segments restriction applies since Vegas does not have fast recovery.
2. To change TTL value, use setTTL(int).
3. To change MSS value, use setMSS(int).
4. To change timer tick, use setTick(double).

References:

• [TCPILL1] W. Stevens, TCP/IP Illustrated vol.1: The Protocols, Addison-Wesley,1994.
• [TCPILL2] G. Wright and W. Stevens, TCP/IP Illustrated vol.2: The Implementation, Addison-Wesley,1995
• [RFC793] J. Postel, Transmission Control Protocol, September 1981.
• [RFC2018] M. Mathis, J. Mahdavi, S. Floyd and A. Romanow, TCP Selective Acknowledgment Options, Octobor 1996.
• [RFC2581] M. Allman, V. Paxson and W. Stevens, TCP Congestion Control, April 1999.
• [Fall96] K. Fall and S. Floyd, Simulation-based Comparisons of Tahoe, Reno and SACK TCP, Computer Comm. Review, V. 26 N. 3, July 1996, pp. 5-21.
• [Brakmo95] L. S. Brakmo and L. L. Peterson, TCP Vegas: End to End Congestion Avoidance on a Global Internet, IEEE Journal on Selected Areas in Communication, Vol 13, No. 8 (October 1995) pages 1465-1480.

Author:

Yuan Gao, Yung-ching Hsiao, Hung-ying Tyan

See Also:

TCPPacket, TCPSink, Serialized Form

Inner Class Summary

static class

TCP.VegasVariables Stores variables for implementing TCP-VEGAS.

Inner classes inherited from class drcl.comp.Component

Component.LockPack

Field Summary

protected Port	ackPort Port to export the acknowledged sequence number of each packet received.
protected long	AWND Receiver window size.
protected int	backoff Current RXT timer backoff value.
protected int	burst # of bytes that have been sent in response to last ACK.
protected long	bytesRetx # of bytes retransmitted.
protected double	cur_rtt Most recent RTT value.
protected double	CWND Congestion window size.
protected Port	cwndPort Port to export the congestion window changed event.
static int	DEBUG_ACK
static int	DEBUG_DUPACK
static java.lang.String[]	DEBUG_LEVELS
static int	DEBUG_RTT
static int	DEBUG_SACK
static int	DEBUG_SAMPLE
static int	DEBUG_SEND
static int	DEBUG_TIMEOUT
static int	DEBUG_VEGAS
protected long	dt_max Maximum seqence number of data in the buffer, = snd_una + sbuffer.size().
protected int	dup_ack Number of duplicated ACKs received.
protected java.lang.String	implementation
protected boolean	maxburst True if maxburst restriction is enabled.
protected double	MAXCWND Maximum congestion window size.
protected double	maxrto Max.
protected int	MSS MSS Maximum segmentation size.
static boolean	NS_COMPATIBLE Sets to true to make TCP ns compatible
protected long	numack # of effective acks received.
protected int	numTimeouts # of coarse-grained timeouts.
protected LongSpace	recvBuffer (Reconstructed) Sequence numbers that the receiver has received.
protected int	rttvar_bits Exponent of weight for updating t_rttvar.
protected int	rttvar_exp Exponent of multiple for t_rtxcur.
protected int	rttvar_init Initial value of RTT Variation (shifted by rttvar_bits)
protected Port	rttvarPort Port to export the RTTVAR event.
protected double	rtxcur_init Initial value of base RXT timer.
protected boolean	SACK True if SACK option is enabled.
protected CircularBuffer	sbuffer Sending buffer.
protected Port	seqNoPort Port to export the [first] sequence number of each packet sent.
protected long	snd_max Maximum seqence number that has been sent.
protected long	snd_nxt Sequence number to send next.
protected long	snd_nxt_marked snd_nxt marked for NEW-RENO and SACK.
protected long	snd_nxt_recorded during Reno-style fast recovery.
protected long	snd_una Smallest sequence number that has not yet been acknowledged.
protected int	srtt_bits Exponent of weight for updating t_srtt.
protected int	srtt_init Initial value of smoothed RTT (shifted by srtt_bits)
protected Port	srttPort Port to export the SRTT event.
protected Port	sstPort Port to export the slow start threshold changed event.
int	state FSM State of this TCP component.
protected long	sthld Congestion avoidance threshold.
protected double	t_grain TCP tick for all the rtt variables.
protected int	t_rttvar RTT Variation (shifted by rttvar_bits)
protected double	t_rtxcur Current RXT timeout value.
protected int	t_srtt Smoothed RTT (shifted by srtt_bits)
protected int	TTL TTL field to IP.
protected TCP.VegasVariables	vegas

Fields inherited from class drcl.net.Module

address, downPort, PortGroup_DOWN, PortGroup_UP, timerPort, upPort

Fields inherited from class drcl.comp.Component

FLAG_COMPONENT_NOTIFICATION, FLAG_DEBUG_ENABLED, FLAG_DIRECT_OUTPUT_ENABLED, FLAG_ENABLED, FLAG_ERROR_ENABLED, FLAG_EVENT_ENABLED, FLAG_GARBAGE_DISPLAY_ENABLED, FLAG_GARBAGE_ENABLED, FLAG_PORT_NOTIFICATION, FLAG_STARTED, FLAG_STOPPED, FLAG_TRACE_ENABLED, FLAG_UNDEFINED_START, id, infoPort, lockHead, name, parent, PortGroup_DEFAULT_GROUP, PortGroup_EVENT, PortGroup_SERVICE, Root, Trace_DATA, Trace_SEND

Fields inherited from interface drcl.inet.transport.TCPConstants

ACK_EVENT, ACK_PORT_ID, AWND_DEFAULT, CLOSE_WAIT, CLOSED, CLOSING, CWND_EVENT, CWND_PORT_ID, DEFAULT_PID, DELAY_ACK, ESTABLISHED, ESTABLISHED_FIN, ESTABLISHED_OVER, FIN_WAIT_1, FIN_WAIT_2, LAST_ACK, LISTEN, LISTEN1, LISTEN2, MAXCWND_DEFAULT, NEW_RENO, NUMDUPACKS, PRE_CLOSED, PRE_LAST_ACK, PRE_SYN_SENT, RECEIVE, RENO, RTT_EVT, RTTVAR_EVENT, RTTVAR_PORT_ID, RXT_EVT, SEND, SEQNO_EVENT, SEQNO_PORT_ID, SEQNO_RCV_EVENT, SEQNO_RCV_PORT_ID, SEQNO_SENT_EVENT, SEQNO_SENT_PORT_ID, SRTT_EVENT, SRTT_PORT_ID, SST_EVENT, SST_PORT_ID, STATES, SYN_RCVD, SYN_SENT, TAHOE, TIME_WAIT, TIMEOUT_TYPES, VEGAS

Fields inherited from interface drcl.inet.InetConstants

BYTE_MODE, DEFAULT_BANDWIDTH, DEFAULT_BUFFER_SIZE, DEFAULT_MTU, EVENT_ID_CHANGED_PORT_ID, EVENT_IDENTITY_ADDED, EVENT_IDENTITY_REMOVED, EVENT_IF_NEIGHBOR_DOWN, EVENT_IF_NEIGHBOR_UP, EVENT_IF_PORT_ID, EVENT_MCAST_HOST_PORT_ID, EVENT_PKT_ARRIVAL, EVENT_PKT_ARRIVAL_PORT_ID, EVENT_RT_ENTRY_ADDED, EVENT_RT_ENTRY_MODIFIED, EVENT_RT_ENTRY_REMOVED, EVENT_RT_MCAST_CHANGED_PORT_ID, EVENT_RT_UCAST_CHANGED_PORT_ID, EVENT_VIF_NEIGHBOR_DOWN, EVENT_VIF_NEIGHBOR_UP, EVENT_VIF_PORT_ID, HOST_ENTRY_EXT, ID_CSL, MCAST_QUERY_PORT_ID, PACKET_MODE, PID_DV, PID_DVMRP, PID_HELLO, PID_IGMP, PID_OSPF, PID_RSVP, PID_TCP, PID_UDP, SERVICE_CONFIGSW_PORT_ID, SERVICE_ID_PORT_ID, SERVICE_IF_PORT_ID, SERVICE_MCAST_PORT_ID, SERVICE_RT_PORT_ID, UCAST_QUERY_PORT_ID

Constructor Summary

TCP()

TCP(java.lang.String id_)

Method Summary

protected void	_start() Used to output initial states events.
protected void	ack_syn_fin(boolean ack_, boolean syn_, boolean fin_)
java.lang.String	configInfo()
void	configureRTT(double tick_, double srtt_init_, double rttvar_init_, double basertt_init_, double maxrto_) Configures RTT parameters.
protected void	dataArriveAtDownPort(java.lang.Object data_, Port downPort_) The handler invoked when a packet arrives at a "down" port.
protected void	dataArriveAtUpPort(java.lang.Object data_, Port upPort_) The handler invoked when a packet arrives at an "up" port.
void	duplicate(java.lang.Object source_) Duplicates the content of source_, including ID, name, child components and connections among them, to this component.
protected int	getAckNo()
protected int	getAvailableRcvBuffer()
double	getBASERTT_INIT() Returns the initial value of baseRTT (in second).
java.lang.String[]	getDebugLevelNames() Returns the names of defined debug levels; subclasses should override this method if debug levels are defined.
java.lang.String	getImplementation()
long	getLocalAddr() Returns the local address.
int	getLocalPort() Returns the local port.
double	getMAXCWND()
double	getMAXRTO() Returns the maximum retr timeout (in second).
int	getMSS()
java.lang.String	getName() Returns the (informational) name of the component.
long	getNumBytesRetransmitted() Returns # of bytes retransmitted.
int	getNumTimeouts() Returns # of coarse-grained timeouts.
long	getPeer() Returns the peer address.
int	getRemotePort() Returns the peer port.
double	getRTTVAR_INIT() Returns the initial value of rttvar (in second).
protected int	getSendingBuffer()
protected int	getSeqNo()
double	getSRTT_INIT() Returns the initial value of srtt (in second).
int	getState()
double	getTick()
int	getTTL()
java.lang.String	info() Returns information regarding this component.
boolean	isMaxburstEnabled()
boolean	isSackEnabled()
protected void	option_process(TCPPacket pkt_, long seq_) Processing TCP header options.
protected void	recv(TCPPacket pkt_) Handles a packet arriving at the down port.
void	reset() Resets the component for being used anew.
protected void	resetRXTTimer(double now_) Resets the retransmission timer.
protected void	rtt_init() Initialize variables for the retransmit timer as in [TCPILL2].
protected void	rtt_update(double now_, double ts_) Update RTT estimations and recalculate RXT timer base.
protected double	rxt_timer(int t_backoff_) Returns the RXT timeout value by multiplying base value and back off value.
protected long	seq_max() Returns the maximum sequence number that can be sent.
void	setBASERTT_INIT(double v_) Sets the initial value of baseRTT (in second).
void	setImplementation(java.lang.String impl_)
void	setMaxburstEnabled(boolean maxburst_)
void	setMAXCWND(long max_)
void	setMAXRTO(double v_) Sets the maximum retr timeout (in second).
void	setMSS(int mss) Sets the maximum segment size.
void	setPeer(long peer_)
void	setRTTVAR_INIT(double v_) Sets the initial value of rttvar (in second).
void	setSackEnabled(boolean sack_)
void	setSRTT_INIT(double v_) Sets the initial value of srtt (in second).
void	setTick(double tick_) Sets the clock tick for RTT estimation.
void	setTTL(int ttl)
protected void	snd_maxpck(java.lang.String debugMsg_) Sends as many packets as allowed by the current window.
protected void	snd_packet(long seqno_, int size_) Sends one packet with specified starting sequence number and packet size.
protected long	snd_wnd() Returns the size of usable window, which is the smaller value of congestion window and window size advertized by peer.
protected void	tcp_init() Initializes this TCP component.
protected void	timeout(java.lang.Object evt_) The handler invoked when a timeout event occurs.
protected void	timer_backoff() Backs off the RXT timer backoff.
protected void	win_decrease(boolean timeout_) Updates congestion window and sending window variables when three duplicate acks are received.
protected void	win_increase() Updates congestion window and sending window variables.
protected void	win_init() Initializes sliding window variables.

Methods inherited from class drcl.inet.Protocol

broadcast, broadcast, broadcast, broadcast, broadcast, broadcast, createConfigSwitchPort, createIDChangedEventPort, createIDServicePort, createIFEventPort, createIFQueryPort, createMcastHostEventPort, createMcastQueryPort, createMulticastRTChangedEventPort, createPktArrivalEventPort, createRTServicePort, createUcastQueryPort, createUnicastRTChangedEventPort, createVIFEventPort, forward, forward, forward, forward, forward, forward, idAddedEventHandler, idRemovedEventHandler, mcastHostJoinEventHandler, mcastHostLeaveEventHandler, mcastQueryHandler, neighborDownEventHandler, neighborUpEventHandler, pktArrivalHandler, processOther, rtAddedEventHandler, rtModifiedEventHandler, rtRemovedEventHandler, ucastQueryHandler, vNeighborDownEventHandler, vNeighborUpEventHandler

Methods inherited from class drcl.net.Module

cancelTimeout, deliver, getAddress, process, removeDefaultDownPort, removeDefaultUpPort, removeTimerPort, setAddress, setTimeout, setTimeoutAt

Methods inherited from class drcl.comp.Component

_resume, _stop, addComponent, addComponent, addEventPort, addEventPort, addForkPort, addPort, addPort, addPort, addPort, addPort, addPort, addPort, addPort, addServerPort, addServerPort, cancelFork, componentAdded, componentRemoved, connect, containsComponent, containsComponent, containsPort, debug, disconnectAll, disconnectAllPeers, disconnectAllPorts, drop, drop, error, error, expose, exposeEventPorts, exposePort, exposePort, exposePort, exposePort, exposePort, findAvailable, findAvailable, findAvailable, finishing, fork, forkAt, getAllComponents, getAllPorts, getAllPorts, getAllWiresInside, getAllWiresInsideOut, getAllWiresOut, getComponent, getComponentFlag, getComponentFlag, getContract, getContractHT, getContractHT, getDebugFlagsInBinary, getForkManager, getID, getParent, getPort, getPort, getRoot, getRuntime, getTime, iduplicate, isAncestorOf, isComponentNotificationEnabled, isContainer, isDebugEnabled, isDebugEnabledAt, isDirectOutputEnabled, isEnabled, isErrorNoticeEnabled, isEventExportEnabled, isGarbageDisplayEnabled, isGarbageEnabled, isPortNotificationEnabled, isPortRemovable, isStarted, isStopped, isTraceEnabled, lock, notify, notifyAll, operate, portAdded, portRemoved, reboot, removeAll, removeAllComponents, removeAllPorts, removeAllPorts, removeComponent, removeComponent, removePort, removePort, removePort, resume, run, sduplicate, send, sendAt, setComponentFlag, setComponentFlag, setComponentNotificationEnabled, setContract, setDebugEnabled, setDebugEnabled, setDebugEnabledAt, setDebugEnabledAt, setDebugEnabledAt, setDirectOutputEnabled, setDirectOutputEnabled, setEnabled, setErrorNoticeEnabled, setErrorNoticeEnabled, setEventExportEnabled, setEventExportEnabled, setExecutionBoundary, setGarbageDisplayEnabled, setGarbageDisplayEnabled, setGarbageEnabled, setGarbageEnabled, setID, setID, setName, setPort, setPort, setPortNotificationEnabled, setPortRemovable, setRuntime, setTraceEnabled, setTraceEnabled, sleepFor, sleepUntil, stop, toString, unexpose, unlock, useLocalForkManager, useLocalForkManager, wait

Methods inherited from class drcl.DrclObj

clone

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

NS_COMPATIBLE

public static boolean NS_COMPATIBLE

Sets to true to make TCP ns compatible

DEBUG_LEVELS

public static final java.lang.String[] DEBUG_LEVELS

DEBUG_ACK

public static final int DEBUG_ACK

DEBUG_DUPACK

public static final int DEBUG_DUPACK

DEBUG_SEND

public static final int DEBUG_SEND

DEBUG_TIMEOUT

public static final int DEBUG_TIMEOUT

DEBUG_RTT

public static final int DEBUG_RTT

DEBUG_SACK

public static final int DEBUG_SACK

DEBUG_SAMPLE

public static final int DEBUG_SAMPLE

DEBUG_VEGAS

public static final int DEBUG_VEGAS

cwndPort

protected Port cwndPort

Port to export the congestion window changed event.

sstPort

protected Port sstPort

Port to export the slow start threshold changed event.

srttPort

protected Port srttPort

Port to export the SRTT event.

rttvarPort

protected Port rttvarPort

Port to export the RTTVAR event.

seqNoPort

protected Port seqNoPort

Port to export the [first] sequence number of each packet sent.

ackPort

protected Port ackPort

Port to export the acknowledged sequence number of each packet received.

srtt_init

protected int srtt_init

Initial value of smoothed RTT (shifted by srtt_bits)

rttvar_init

protected int rttvar_init

Initial value of RTT Variation (shifted by rttvar_bits)

rtxcur_init

protected double rtxcur_init

Initial value of base RXT timer.

t_grain

protected double t_grain

TCP tick for all the rtt variables. The tick value is set as 100 ms (0.1 second) as the fast timer in [TCPILL2].

t_srtt

protected transient int t_srtt

Smoothed RTT (shifted by srtt_bits)

t_rttvar

protected transient int t_rttvar

RTT Variation (shifted by rttvar_bits)

t_rtxcur

protected transient double t_rtxcur

Current RXT timeout value.

backoff

protected transient int backoff

Current RXT timer backoff value.

srtt_bits

protected int srtt_bits

Exponent of weight for updating t_srtt.

rttvar_bits

protected int rttvar_bits

Exponent of weight for updating t_rttvar.

rttvar_exp

protected int rttvar_exp

Exponent of multiple for t_rtxcur.

maxrto

protected double maxrto

Max. value of a RXT timeout.

cur_rtt

protected transient double cur_rtt

Most recent RTT value.

vegas

protected transient TCP.VegasVariables vegas

TTL

protected int TTL

TTL field to IP.

MSS

protected int MSS

MSS Maximum segmentation size.

implementation

protected java.lang.String implementation

CWND

protected transient double CWND

Congestion window size.

MAXCWND

protected double MAXCWND

Maximum congestion window size.

AWND

protected transient long AWND

Receiver window size.

sthld

protected transient long sthld

Congestion avoidance threshold.

snd_una

protected transient long snd_una

Smallest sequence number that has not yet been acknowledged.

snd_nxt

protected transient long snd_nxt

Sequence number to send next.

snd_nxt_recorded

protected transient long snd_nxt_recorded

during Reno-style fast recovery.

snd_nxt_marked

protected transient long snd_nxt_marked

snd_nxt marked for NEW-RENO and SACK.

snd_max

protected transient long snd_max

Maximum seqence number that has been sent.

dt_max

protected transient long dt_max

Maximum seqence number of data in the buffer, = snd_una + sbuffer.size().

dup_ack

protected transient int dup_ack

Number of duplicated ACKs received.

numack

protected transient long numack

# of effective acks received.

sbuffer

protected transient CircularBuffer sbuffer

Sending buffer.

bytesRetx

protected transient long bytesRetx

# of bytes retransmitted.

numTimeouts

protected transient int numTimeouts

# of coarse-grained timeouts.

burst

protected transient int burst

# of bytes that have been sent in response to last ACK.

SACK

protected boolean SACK

True if SACK option is enabled. Default is false.

maxburst

protected boolean maxburst

True if maxburst restriction is enabled. Default is true.

recvBuffer

protected transient LongSpace recvBuffer

(Reconstructed) Sequence numbers that the receiver has received.

state

public transient int state

FSM State of this TCP component.

Constructor Detail

TCP

public TCP()

TCP

public TCP(java.lang.String id_)

Method Detail

getDebugLevelNames

public java.lang.String[] getDebugLevelNames()

Description copied from class: Component

Returns the names of defined debug levels; subclasses should override this method if debug levels are defined.

Overrides:

getDebugLevelNames in class Component

getName

public java.lang.String getName()

Description copied from class: Component

Returns the (informational) name of the component.

Overrides:

getName in class Component

reset

public void reset()

Description copied from class: Component

Resets the component for being used anew. All the internal variables must be set to the initial state. All the ports and child components are reset as well.

Overrides:

reset in class Component

duplicate

public void duplicate(java.lang.Object source_)

Description copied from class: Component

Duplicates the content of source_, including ID, name, child components and connections among them, to this component. Subclasses need to override this method to copy its own variables.

Overrides:

duplicate in class Protocol

_start

protected void _start()

Used to output initial states events.

Overrides:

_start in class Component

getState

public int getState()

setPeer

public void setPeer(long peer_)

getPeer

public long getPeer()

Description copied from interface: drcl.inet.transport.Connection

Returns the peer address.

Specified by:

getPeer in interface drcl.inet.transport.Connection

setTTL

public void setTTL(int ttl)

getTTL

public int getTTL()

setMSS

public void setMSS(int mss)

Sets the maximum segment size. This method initializes this TCP component. Should not be called during simulation.

getMSS

public int getMSS()

setMAXCWND

public void setMAXCWND(long max_)

getMAXCWND

public double getMAXCWND()

setTick

public void setTick(double tick_)

Sets the clock tick for RTT estimation.

getTick

public double getTick()

setSRTT_INIT

public void setSRTT_INIT(double v_)

Sets the initial value of srtt (in second).

getSRTT_INIT

public double getSRTT_INIT()

Returns the initial value of srtt (in second).

setRTTVAR_INIT

public void setRTTVAR_INIT(double v_)

Sets the initial value of rttvar (in second).

getRTTVAR_INIT

public double getRTTVAR_INIT()

Returns the initial value of rttvar (in second).

setBASERTT_INIT

public void setBASERTT_INIT(double v_)

Sets the initial value of baseRTT (in second).

getBASERTT_INIT

public double getBASERTT_INIT()

Returns the initial value of baseRTT (in second).

setMAXRTO

public void setMAXRTO(double v_)

Sets the maximum retr timeout (in second).

getMAXRTO

public double getMAXRTO()

Returns the maximum retr timeout (in second).

getNumBytesRetransmitted

public long getNumBytesRetransmitted()

Returns # of bytes retransmitted.

getNumTimeouts

public int getNumTimeouts()

Returns # of coarse-grained timeouts.

configureRTT

public void configureRTT(double tick_,
                         double srtt_init_,
                         double rttvar_init_,
                         double basertt_init_,
                         double maxrto_)

Configures RTT parameters.

Parameters:

tick_ - time unit for RTT variables.

srtt_init_ - initial value of srtt.

rttvar_init_ - initial value of rttvar.

basertt_init_ - initial value of baseRTT.

maxrto_ - maximum retrx timeout.

setImplementation

public void setImplementation(java.lang.String impl_)

getImplementation

public java.lang.String getImplementation()

setSackEnabled

public void setSackEnabled(boolean sack_)

isSackEnabled

public boolean isSackEnabled()

setMaxburstEnabled

public void setMaxburstEnabled(boolean maxburst_)

isMaxburstEnabled

public boolean isMaxburstEnabled()

tcp_init

protected void tcp_init()

Initializes this TCP component.

rtt_init

protected void rtt_init()

Initialize variables for the retransmit timer as in [TCPILL2].

rtt_update

protected void rtt_update(double now_,
                          double ts_)

Update RTT estimations and recalculate RXT timer base. The estimation method is same as in [TCPILL2]. The sending time of a packet is carried back by acknowledgment packet as ts_ in header (which doesn't exist in real world TCP/IP header). When ts_ is -1, the packet is a retransmitted one, so no RTT estimation updating is done for this packet. The algorithm is described in [RFC793] and [TCPILL1]. SampleRTT = current time - ts_; SmoothedRTT[new] = 7/8*SmoothedRTT[old] + 1/8*SampleRTT; Delta = |SampleRTT - SmoothedRTT[old]|; RTTVariance[new] = 3/4*RTTVariance[old] + 1/4*Delta; and the retransmission timer base is RTO[new] = SmoothedRTT[new] + 4*RTTVariance[new]. The exception is that for the first acknowledgment received: SampleRTT = current time - ts_; SmoothedRTT[new] = SampleRTT; RTTVariance[new] = SampleRTT/2; and the retransmission timer base is RTO[new] = SmoothedRTT[new] + 4*RTTVariance[new].

Parameters:

ts_ - the sending time of the acknowledged packet.

rxt_timer

protected double rxt_timer(int t_backoff_)

Returns the RXT timeout value by multiplying base value and back off value.

Parameters:

t_backoff - RXT timer backoff value

win_init

protected void win_init()

Initializes sliding window variables. Congestion window and slow start threshold is set as in [TCPILL2].

snd_wnd

protected long snd_wnd()

Returns the size of usable window, which is the smaller value of congestion window and window size advertized by peer.

seq_max

protected long seq_max()

Returns the maximum sequence number that can be sent.

dataArriveAtUpPort

protected void dataArriveAtUpPort(java.lang.Object data_,
                                  Port upPort_)

Description copied from class: Module

The handler invoked when a packet arrives at an "up" port. Subclasses should override it to handle such an event.

Overrides:

dataArriveAtUpPort in class Module

dataArriveAtDownPort

protected void dataArriveAtDownPort(java.lang.Object data_,
                                    Port downPort_)

Description copied from class: Module

The handler invoked when a packet arrives at a "down" port. Subclasses should override it to handle such an event.

Overrides:

dataArriveAtDownPort in class Module

recv

protected void recv(TCPPacket pkt_)

Handles a packet arriving at the down port.

option_process

protected void option_process(TCPPacket pkt_,
                              long seq_)

Processing TCP header options.

win_increase

protected void win_increase()

Updates congestion window and sending window variables. The congestion window updating is according to [RFC2581].

win_decrease

protected void win_decrease(boolean timeout_)

Updates congestion window and sending window variables when three duplicate acks are received.

timer_backoff

protected void timer_backoff()

Backs off the RXT timer backoff. The largest backoff value is 64 as specified in [RFC2581].

timeout

protected void timeout(java.lang.Object evt_)

Description copied from class: Module

The handler invoked when a timeout event occurs. Subclasses should override it to handle such an event.

Overrides:

timeout in class Module

Following copied from class: drcl.net.Module

See Also:

Module.setTimeout(Object, double), Module.setTimeoutAt(Object, double)

snd_maxpck

protected void snd_maxpck(java.lang.String debugMsg_)

Sends as many packets as allowed by the current window.

snd_packet

protected void snd_packet(long seqno_,
                          int size_)

Sends one packet with specified starting sequence number and packet size.

resetRXTTimer

protected void resetRXTTimer(double now_)

Resets the retransmission timer.

ack_syn_fin

protected void ack_syn_fin(boolean ack_,
                           boolean syn_,
                           boolean fin_)

getLocalPort

public int getLocalPort()

Description copied from interface: drcl.inet.transport.Connection

Returns the local port.

Specified by:

getLocalPort in interface drcl.inet.transport.Connection

getRemotePort

public int getRemotePort()

Description copied from interface: drcl.inet.transport.Connection

Returns the peer port.

Specified by:

getRemotePort in interface drcl.inet.transport.Connection

getLocalAddr

public long getLocalAddr()

Description copied from interface: drcl.inet.transport.Connection

Returns the local address.

Specified by:

getLocalAddr in interface drcl.inet.transport.Connection

getSeqNo

protected int getSeqNo()

getAckNo

protected int getAckNo()

getAvailableRcvBuffer

protected int getAvailableRcvBuffer()

getSendingBuffer

protected int getSendingBuffer()

info

public java.lang.String info()

Description copied from class: Component

Returns information regarding this component. Subclasses should override this method to provide useful information at run-time.

Overrides:

info in class Component

configInfo

public java.lang.String configInfo()