The Cubic Congestion Control Algorithm. More...

#include "tcp-cubic.h"

Inheritance diagram for ns3::TcpCubic:

Collaboration diagram for ns3::TcpCubic:

Public Types
enum	HybridSSDetectionMode { PACKET_TRAIN = 1 , DELAY = 2 , BOTH = 3 }
	Values to detect the Slow Start mode of HyStart. More...

Public Member Functions
	TcpCubic ()

	TcpCubic (const TcpCubic &sock)
	Copy constructor.

void	CongestionStateSet (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCongState_t newState) override
	Trigger events/calculations specific to a congestion state.

Ptr< TcpCongestionOps >	Fork () override
	Copy the congestion control algorithm across sockets.

std::string	GetName () const override
	Get the name of the congestion control algorithm.

uint32_t	GetSsThresh (Ptr< const TcpSocketState > tcb, uint32_t bytesInFlight) override
	Get the slow start threshold after a loss event.

void	IncreaseWindow (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override
	Congestion avoidance algorithm implementation.

void	PktsAcked (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked, const Time &rtt) override
	Timing information on received ACK.

Public Member Functions inherited from ns3::TcpCongestionOps
	TcpCongestionOps ()

	TcpCongestionOps (const TcpCongestionOps &other)
	Copy constructor.

	~TcpCongestionOps () override

virtual void	CongControl (Ptr< TcpSocketState > tcb, const TcpRateOps::TcpRateConnection &rc, const TcpRateOps::TcpRateSample &rs)
	Called when packets are delivered to update cwnd and pacing rate.

virtual void	CongestionStateSet (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCongState_t newState)
	Trigger events/calculations specific to a congestion state.

virtual void	CwndEvent (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCAEvent_t event)
	Trigger events/calculations on occurrence of congestion window event.

virtual Ptr< TcpCongestionOps >	Fork ()=0
	Copy the congestion control algorithm across sockets.

virtual std::string	GetName () const =0
	Get the name of the congestion control algorithm.

virtual uint32_t	GetSsThresh (Ptr< const TcpSocketState > tcb, uint32_t bytesInFlight)=0
	Get the slow start threshold after a loss event.

virtual bool	HasCongControl () const
	Returns true when Congestion Control Algorithm implements CongControl.

virtual void	IncreaseWindow (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
	Congestion avoidance algorithm implementation.

virtual void	Init (Ptr< TcpSocketState > tcb)
	Set configuration required by congestion control algorithm.

virtual void	PktsAcked (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked, const Time &rtt)
	Timing information on received ACK.

Public Member Functions inherited from ns3::Object
	Object ()
	Constructor.

	~Object () override
	Destructor.

void	AggregateObject (Ptr< Object > other)
	Aggregate two Objects together.

void	Dispose ()
	Dispose of this Object.

AggregateIterator	GetAggregateIterator () const
	Get an iterator to the Objects aggregated to this one.

TypeId	GetInstanceTypeId () const override
	Get the most derived TypeId for this Object.

template<typename T >
Ptr< T >	GetObject () const
	Get a pointer to the requested aggregated Object.

template<>
Ptr< Object >	GetObject () const
	Specialization of () for objects of type ns3::Object.

template<typename T >
Ptr< T >	GetObject (TypeId tid) const
	Get a pointer to the requested aggregated Object by TypeId.

template<>
Ptr< Object >	GetObject (TypeId tid) const
	Specialization of (TypeId tid) for objects of type ns3::Object.

void	Initialize ()
	Invoke DoInitialize on all Objects aggregated to this one.

bool	IsInitialized () const
	Check if the object has been initialized.

void	UnidirectionalAggregateObject (Ptr< Object > other)
	Aggregate an Object to another Object.

Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
	SimpleRefCount ()
	Default constructor.

	SimpleRefCount (const SimpleRefCount &o)
	Copy constructor.

uint32_t	GetReferenceCount () const
	Get the reference count of the object.

SimpleRefCount &	operator= (const SimpleRefCount &o)
	Assignment operator.

void	Ref () const
	Increment the reference count.

void	Unref () const
	Decrement the reference count.

Public Member Functions inherited from ns3::ObjectBase
virtual	~ObjectBase ()
	Virtual destructor.

void	GetAttribute (std::string name, AttributeValue &value) const
	Get the value of an attribute, raising fatal errors if unsuccessful.

bool	GetAttributeFailSafe (std::string name, AttributeValue &value) const
	Get the value of an attribute without raising errors.

virtual TypeId	GetInstanceTypeId () const =0
	Get the most derived TypeId for this Object.

void	SetAttribute (std::string name, const AttributeValue &value)
	Set a single attribute, raising fatal errors if unsuccessful.

bool	SetAttributeFailSafe (std::string name, const AttributeValue &value)
	Set a single attribute without raising errors.

bool	TraceConnect (std::string name, std::string context, const CallbackBase &cb)
	Connect a TraceSource to a Callback with a context.

bool	TraceConnectWithoutContext (std::string name, const CallbackBase &cb)
	Connect a TraceSource to a Callback without a context.

bool	TraceDisconnect (std::string name, std::string context, const CallbackBase &cb)
	Disconnect from a TraceSource a Callback previously connected with a context.

bool	TraceDisconnectWithoutContext (std::string name, const CallbackBase &cb)
	Disconnect from a TraceSource a Callback previously connected without a context.

Static Public Member Functions
static TypeId	GetTypeId ()
	Get the type ID.

Static Public Member Functions inherited from ns3::TcpCongestionOps
static TypeId	GetTypeId ()
	Get the type ID.

Static Public Member Functions inherited from ns3::Object
static TypeId	GetTypeId ()
	Register this type.

Static Public Member Functions inherited from ns3::ObjectBase
static TypeId	GetTypeId ()
	Get the type ID.

Private Member Functions
void	CubicReset (Ptr< const TcpSocketState > tcb)
	Reset Cubic parameters.

Time	HystartDelayThresh (const Time &t) const
	Clamp time value in a range.

void	HystartReset (Ptr< const TcpSocketState > tcb)
	Reset HyStart parameters.

void	HystartUpdate (Ptr< TcpSocketState > tcb, const Time &delay)
	Update HyStart parameters.

uint32_t	Update (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
	Cubic window update after a new ack received.

Private Attributes
uint32_t	m_ackCnt
	Count the number of ACKed packets.

double	m_beta
	Beta for cubic multiplicative increase.

double	m_bicK
	Time to origin point from the beginning.

uint32_t	m_bicOriginPoint
	Origin point of bic function.

double	m_c
	Cubic Scaling factor.

uint8_t	m_cntClamp
	Modulo of the (avoided) float division for cWnd.

Time	m_cubicDelta
	Time to wait after recovery before update.

Time	m_currRtt
	Current Rtt.

uint32_t	m_cWndCnt
	cWnd integer-to-float counter

Time	m_delayMin
	Min delay.

SequenceNumber32	m_endSeq
	End sequence of the round.

Time	m_epochStart
	Beginning of an epoch.

bool	m_fastConvergence
	Enable or disable fast convergence algorithm.

bool	m_found
	The exit point is found?

bool	m_hystart
	Enable or disable HyStart algorithm.

Time	m_hystartAckDelta
	Spacing between ack's indicating train.

Time	m_hystartDelayMax
	Maximum time for hystart algorithm.

Time	m_hystartDelayMin
	Minimum time for hystart algorithm.

HybridSSDetectionMode	m_hystartDetect
	Detect way for HyStart algorithm.

uint32_t	m_hystartLowWindow
	Lower bound cWnd for hybrid slow start (segments)

uint8_t	m_hystartMinSamples
	Number of delay samples for detecting the increase of delay.

uint32_t	m_initialCwnd
	Initial cWnd.

Time	m_lastAck
	Last time when the ACK spacing is close.

uint32_t	m_lastMaxCwnd
	Last maximum cWnd.

Time	m_roundStart
	Beginning of each round.

uint32_t	m_sampleCnt
	Count of samples for HyStart.

uint32_t	m_tcpCwnd
	Estimated tcp cwnd (for Reno-friendliness)

bool	m_tcpFriendliness
	Enable or disable TCP-friendliness heuristic.

Additional Inherited Members
Protected Member Functions inherited from ns3::Object
	Object (const Object &o)
	Copy an Object.

virtual void	DoDispose ()
	Destructor implementation.

virtual void	DoInitialize ()
	Initialize() implementation.

virtual void	NotifyNewAggregate ()
	Notify all Objects aggregated to this one of a new Object being aggregated.

Protected Member Functions inherited from ns3::ObjectBase
void	ConstructSelf (const AttributeConstructionList &attributes)
	Complete construction of ObjectBase; invoked by derived classes.

virtual void	NotifyConstructionCompleted ()
	Notifier called once the ObjectBase is fully constructed.

Related Functions inherited from ns3::ObjectBase
static TypeId	GetObjectIid ()
	Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly.

Detailed Description

The Cubic Congestion Control Algorithm.

TCP Cubic is a protocol that enhances the fairness property of Bic while retaining its scalability and stability. The main feature is that the window growth function is defined in real time in order to be independent from the RTT. More specifically, the congestion window of Cubic is determined by a function of the elapsed time from the last window reduction.

The Cubic code is quite similar to that of Bic. The main difference is located in the method Update, an edit necessary for satisfying the Cubic window growth, that can be tuned with the attribute C (the Cubic scaling factor).

Following the Linux implementation, we included the Hybrid Slow Start, that effectively prevents the overshooting of slow start while maintaining a full utilization of the network. This new type of slow start can be disabled through the HyStart attribute.

CUBIC TCP is implemented and used by default in Linux kernels 2.6.19 and above; this version follows the implementation in Linux 3.14, which slightly differ from the CUBIC paper. It also features HyStart.

Home page: https://web.archive.org/web/20080607093013/http://netsrv.csc.ncsu.edu/twiki/bin/view/Main/BIC The work starts from the implementation of CUBIC TCP in Sangtae Ha, Injong Rhee and Lisong Xu, "CUBIC: A New TCP-Friendly High-Speed TCP Variant" in ACM SIGOPS Operating System Review, July 2008. Available from: https://web.archive.org/web/20160505194415/http://netsrv.csc.ncsu.edu/export/cubic_a_new_tcp_2008.pdf

CUBIC integrates a new slow start algorithm, called HyStart. The details of HyStart are presented in Sangtae Ha and Injong Rhee, "Taming the Elephants: New TCP Slow Start", NCSU TechReport 2008. Available from: https://web.archive.org/web/20160528233754/http://netsrv.csc.ncsu.edu/export/hystart_techreport_2008.pdf

More information on this implementation: http://dl.acm.org/citation.cfm?id=2756518

Config Paths

ns3::TcpCubic is accessible through the following paths with Config::Set and Config::Connect:

"/NodeList/[i]/$ns3::TcpL4Protocol/SocketList/[i]/$ns3::TcpCubic"

Attributes

Beta: Beta for multiplicative decrease
- Set with class: ns3::DoubleValue
- Underlying type: double 0:1.79769e+308
- Initial value: 0.7
- Flags: constructwriteread
C: Cubic Scaling factor
- Set with class: ns3::DoubleValue
- Underlying type: double 0:1.79769e+308
- Initial value: 0.4
- Flags: constructwriteread
CntClamp: Counter value when no losses are detected (counter is used when incrementing cWnd in congestion avoidance, to avoid floating point arithmetic). It is the modulo of the (avoided) division
- Set with class: ns3::UintegerValue
- Underlying type: uint8_t 0:255
- Initial value: 20
- Flags: constructwriteread
CubicDelta: Delta Time to wait after fast recovery before adjusting param
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +1e+07ns
- Flags: constructwriteread
FastConvergence: Enable (true) or disable (false) fast convergence
- Set with class: ns3::BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: constructwriteread
HyStart: Enable (true) or disable (false) hybrid slow start algorithm
- Set with class: ns3::BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: constructwriteread
HyStartAckDelta: Spacing between ack's indicating train
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +2e+06ns
- Flags: constructwriteread
HyStartDelayMax: Maximum time for hystart algorithm
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +1e+09ns
- Flags: constructwriteread
HyStartDelayMin: Minimum time for hystart algorithm
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +4e+06ns
- Flags: constructwriteread
HyStartDetect: Hybrid Slow Start detection mechanisms:packet train, delay, both
- Set with class: ns3::EnumValue<N3ns38TcpCubic21HybridSSDetectionModeE>
- Underlying type: PACKET_TRAIN|DELAY|BOTH
- Initial value: BOTH
- Flags: constructwriteread
HyStartLowWindow: Lower bound cWnd for hybrid slow start (segments)
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 16
- Flags: constructwriteread
HyStartMinSamples: Number of delay samples for detecting the increase of delay
- Set with class: ns3::UintegerValue
- Underlying type: uint8_t 0:255
- Initial value: 8
- Flags: constructwriteread
TcpFriendliness: Enable (true) or disable (false) TCP friendliness
- Set with class: ns3::BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: constructwriteread

Attributes defined in parent class ns3::TcpSocketBase

ClockGranularity: Clock Granularity used in RTO calculations
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +1e+06ns
- Flags: constructwriteread
CongestionOps: Pointer to TcpCongestionOps object
- Set with class: ns3::PointerValue
- Underlying type: ns3::Ptr< ns3::TcpCongestionOps>
- Initial value: 0
- Flags: constructwriteread
IcmpCallback: Callback invoked whenever an icmp error is received on this socket.
- Set with class: ns3::CallbackValue
- Underlying type: Callback
- Initial value: 0
- Flags: constructwriteread
IcmpCallback6: Callback invoked whenever an icmpv6 error is received on this socket.
- Set with class: ns3::CallbackValue
- Underlying type: Callback
- Initial value: 0
- Flags: constructwriteread
LimitedTransmit: Enable limited transmit
- Set with class: ns3::BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: constructwriteread
MaxSegLifetime: Maximum segment lifetime in seconds, use for TIME_WAIT state transition to CLOSED state
- Set with class: ns3::DoubleValue
- Underlying type: double 0:1.79769e+308
- Initial value: 120
- Flags: constructwriteread
MaxWindowSize: Max size of advertised window
- Set with class: ns3::UintegerValue
- Underlying type: uint16_t 0:65535
- Initial value: 65535
- Flags: constructwriteread
MinRto: Minimum retransmit timeout value
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +1e+09ns
- Flags: constructwriteread
ReTxThreshold: Threshold for fast retransmit
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 3
- Flags: constructwriteread
RxBuffer: TCP Rx buffer
- Set with class: ns3::PointerValue
- Underlying type: ns3::Ptr< ns3::TcpRxBuffer>
- Flags: read
Sack: Enable or disable Sack option
- Set with class: ns3::BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: constructwriteread
Timestamp: Enable or disable Timestamp option
- Set with class: ns3::BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: constructwriteread
TxBuffer: TCP Tx buffer
- Set with class: ns3::PointerValue
- Underlying type: ns3::Ptr< ns3::TcpTxBuffer>
- Flags: read
UseEcn: Parameter to set ECN functionality
- Set with class: ns3::EnumValue<N3ns314TcpSocketState8UseEcn_tE>
- Underlying type: Off|On|AcceptOnly
- Initial value: Off
- Flags: constructwrite
WindowScaling: Enable or disable Window Scaling option
- Set with class: ns3::BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: constructwriteread

Attributes defined in parent class ns3::TcpSocket

ConnCount: Number of connection attempts (SYN retransmissions) before returning failure
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 6
- Flags: constructwriteread
ConnTimeout: TCP retransmission timeout when opening connection (seconds)
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +3e+09ns
- Flags: constructwriteread
DataRetries: Number of data retransmission attempts
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 6
- Flags: constructwriteread
DelAckCount: Number of packets to wait before sending a TCP ack
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 2
- Flags: constructwriteread
DelAckTimeout: Timeout value for TCP delayed acks, in seconds
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +2e+08ns
- Flags: constructwriteread
InitialCwnd: TCP initial congestion window size (segments)
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 10
- Flags: constructwriteread
InitialSlowStartThreshold: TCP initial slow start threshold (bytes)
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 4294967295
- Flags: constructwriteread
PersistTimeout: Persist timeout to probe for rx window
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +6e+09ns
- Flags: constructwriteread
RcvBufSize: TcpSocket maximum receive buffer size (bytes)
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 131072
- Flags: constructwriteread
SegmentSize: TCP maximum segment size in bytes (may be adjusted based on MTU discovery)
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 536
- Flags: constructwriteread
SndBufSize: TcpSocket maximum transmit buffer size (bytes)
- Set with class: ns3::UintegerValue
- Underlying type: uint32_t 0:4294967295
- Initial value: 131072
- Flags: constructwriteread
TcpNoDelay: Set to true to disable Nagle's algorithm
- Set with class: ns3::BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: constructwriteread

No TraceSources are defined for this type.

TraceSources defined in parent class ns3::TcpSocketBase

AdvWND: Advertised Window Size
Callback signature: ns3::TracedValueCallback::Uint32
BytesInFlight: Socket estimation of bytes in flight
Callback signature: ns3::TracedValueCallback::Uint32
CongState: TCP Congestion machine state
Callback signature: ns3::TcpSocketState::TcpCongStatesTracedValueCallback
CongestionWindow: The TCP connection's congestion window
Callback signature: ns3::TracedValueCallback::Uint32
CongestionWindowInflated: The TCP connection's congestion window inflates as in older RFC
Callback signature: ns3::TracedValueCallback::Uint32
EcnCeSeq: Sequence of last received CE
Callback signature: ns3::SequenceNumber32TracedValueCallback
EcnCwrSeq: Sequence of last received CWR
Callback signature: ns3::SequenceNumber32TracedValueCallback
EcnEchoSeq: Sequence of last received ECN Echo
Callback signature: ns3::SequenceNumber32TracedValueCallback
EcnState: Trace ECN state change of socket
Callback signature: ns3::TcpSocketState::EcnStatesTracedValueCallback
HighestRxAck: Highest ack received from peer
Callback signature: ns3::TracedValueCallback::SequenceNumber32
HighestRxSequence: Highest sequence number received from peer
Callback signature: ns3::TracedValueCallback::SequenceNumber32
HighestSequence: Highest sequence number ever sent in socket's life time
Callback signature: ns3::TracedValueCallback::SequenceNumber32
NextTxSequence: Next sequence number to send (SND.NXT)
Callback signature: ns3::SequenceNumber32TracedValueCallback
PacingRate: The current TCP pacing rate
Callback signature: ns3::TracedValueCallback::DataRate
RTO: Retransmission timeout
Callback signature: ns3::TracedValueCallback::Time
RTT: Last RTT sample
Callback signature: ns3::TracedValueCallback::Time
RWND: Remote side's flow control window
Callback signature: ns3::TracedValueCallback::Uint32
Rx: Receive tcp packet from IP protocol
Callback signature: ns3::TcpSocketBase::TcpTxRxTracedCallback
SlowStartThreshold: TCP slow start threshold (bytes)
Callback signature: ns3::TracedValueCallback::Uint32
State: TCP state
Callback signature: ns3::TcpStatesTracedValueCallback
Tx: Send tcp packet to IP protocol
Callback signature: ns3::TcpSocketBase::TcpTxRxTracedCallback

Size of this type is 232 bytes (on a 64-bit architecture).

Definition at line 69 of file tcp-cubic.h.

Member Enumeration Documentation

◆ HybridSSDetectionMode

enum ns3::TcpCubic::HybridSSDetectionMode

Values to detect the Slow Start mode of HyStart.

Enumerator
PACKET_TRAIN	Detection by trains of packet.
DELAY	Detection by delay value.
BOTH	Detection by both.

Definition at line 75 of file tcp-cubic.h.

Constructor & Destructor Documentation

◆ TcpCubic() [1/2]

ns3::TcpCubic::TcpCubic ( )

Definition at line 120 of file tcp-cubic.cc.

References NS_LOG_FUNCTION.

◆ TcpCubic() [2/2]

ns3::TcpCubic::TcpCubic ( const TcpCubic & sock )

Copy constructor.

Parameters

sock	Socket to copy

Definition at line 139 of file tcp-cubic.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CongestionStateSet()

void ns3::TcpCubic::CongestionStateSet	(	Ptr< TcpSocketState >	tcb,
		const TcpSocketState::TcpCongState_t	newState
	)

overridevirtual

Trigger events/calculations specific to a congestion state.

This function mimics the notification function set_state in Linux. The function does not change the congestion state in the tcb; it notifies the congestion control algorithm that this state is about to be changed. The tcb->m_congState variable must be separately set; for example:

m_congestionControl->CongestionStateSet (m_tcb, TcpSocketState::CA_RECOVERY);

m_tcb->m_congState = TcpSocketState::CA_RECOVERY;

ns3::TcpSocketState::CA_RECOVERY

@ CA_RECOVERY

CWND was reduced, we are fast-retransmitting.

Definition: tcp-socket-state.h:88

Parameters

tcb	internal congestion state
newState	new congestion state to which the TCP is going to switch

Reimplemented from ns3::TcpCongestionOps.

Definition at line 477 of file tcp-cubic.cc.

References ns3::TcpSocketState::CA_LOSS, CubicReset(), HystartReset(), and NS_LOG_FUNCTION.

Here is the call graph for this function:

◆ CubicReset()

void ns3::TcpCubic::CubicReset ( Ptr< const TcpSocketState > tcb )

private

Reset Cubic parameters.

Parameters

tcb	Transmission Control Block of the connection

Definition at line 489 of file tcp-cubic.cc.

References m_ackCnt, m_bicK, m_bicOriginPoint, m_delayMin, m_found, m_lastMaxCwnd, m_tcpCwnd, ns3::Time::Min(), and NS_LOG_FUNCTION.

Referenced by CongestionStateSet().

Here is the call graph for this function:

Here is the caller graph for this function:

◆ Fork()

Ptr< TcpCongestionOps > ns3::TcpCubic::Fork ( )

overridevirtual

Copy the congestion control algorithm across sockets.

Returns: a pointer of the copied object

Implements ns3::TcpCongestionOps.

Definition at line 503 of file tcp-cubic.cc.

References NS_LOG_FUNCTION.

◆ GetName()

std::string ns3::TcpCubic::GetName ( ) const

overridevirtual

Get the name of the congestion control algorithm.

Returns: A string identifying the name

Implements ns3::TcpCongestionOps.

Definition at line 171 of file tcp-cubic.cc.

◆ GetSsThresh()

uint32_t ns3::TcpCubic::GetSsThresh	(	Ptr< const TcpSocketState >	tcb,
		uint32_t	bytesInFlight
	)

overridevirtual

Get the slow start threshold after a loss event.

Is guaranteed that the congestion control state (TcpAckState_t) is changed BEFORE the invocation of this method. The implementer should return the slow start threshold (and not change it directly) because, in the future, the TCP implementation may require to instantly recover from a loss event (e.g. when there is a network with an high reordering factor).

Parameters

tcb	internal congestion state
bytesInFlight	total bytes in flight

Returns: Slow start threshold

Implements ns3::TcpCongestionOps.

Definition at line 448 of file tcp-cubic.cc.

References m_beta, m_epochStart, m_fastConvergence, m_lastMaxCwnd, ns3::Time::Min(), NS_LOG_DEBUG, and NS_LOG_FUNCTION.

Here is the call graph for this function:

◆ GetTypeId()

TypeId ns3::TcpCubic::GetTypeId ( )

static

Get the type ID.

Returns: the object TypeId

Definition at line 36 of file tcp-cubic.cc.

References BOTH, DELAY, m_beta, m_c, m_cntClamp, m_cubicDelta, m_fastConvergence, m_hystart, m_hystartAckDelta, m_hystartDelayMax, m_hystartDelayMin, m_hystartDetect, m_hystartLowWindow, m_hystartMinSamples, m_tcpFriendliness, ns3::MakeBooleanAccessor(), ns3::MakeBooleanChecker(), ns3::MakeDoubleAccessor(), ns3::MakeEnumChecker(), ns3::MakeTimeAccessor(), ns3::MakeTimeChecker(), ns3::MakeUintegerAccessor(), ns3::MilliSeconds(), PACKET_TRAIN, and ns3::TypeId::SetParent().

Referenced by ns3::TcpL4Protocol::GetTypeId().

Here is the call graph for this function:

Here is the caller graph for this function:

◆ HystartDelayThresh()

Time ns3::TcpCubic::HystartDelayThresh ( const Time & t ) const

private

Clamp time value in a range.

The returned value is t, clamped in a range specified by attributes (HystartDelayMin < t < HystartDelayMax)

Parameters

t	Time value to clamp

Returns: t itself if it is in range, otherwise the min or max value

Definition at line 430 of file tcp-cubic.cc.

References m_hystartDelayMax, m_hystartDelayMin, and NS_LOG_FUNCTION.

Referenced by HystartUpdate().

Here is the caller graph for this function:

◆ HystartReset()

void ns3::TcpCubic::HystartReset ( Ptr< const TcpSocketState > tcb )

private

Reset HyStart parameters.

Parameters

tcb	Transmission Control Block of the connection

Definition at line 177 of file tcp-cubic.cc.

References m_currRtt, m_endSeq, m_lastAck, m_roundStart, m_sampleCnt, ns3::Time::Min(), ns3::Simulator::Now(), and NS_LOG_FUNCTION.

Referenced by CongestionStateSet(), and IncreaseWindow().

Here is the call graph for this function:

Here is the caller graph for this function:

◆ HystartUpdate()

void ns3::TcpCubic::HystartUpdate	(	Ptr< TcpSocketState >	tcb,
		const Time &	delay
	)

private

Update HyStart parameters.

Parameters

tcb	Transmission Control Block of the connection
delay	Delay for HyStart algorithm

Definition at line 375 of file tcp-cubic.cc.

References BOTH, DELAY, HystartDelayThresh(), m_currRtt, m_delayMin, m_found, m_hystartAckDelta, m_hystartDetect, m_hystartMinSamples, m_lastAck, m_roundStart, m_sampleCnt, ns3::Time::Min(), ns3::Simulator::Now(), NS_LOG_DEBUG, NS_LOG_FUNCTION, and PACKET_TRAIN.

Referenced by PktsAcked().

Here is the call graph for this function:

Here is the caller graph for this function:

◆ IncreaseWindow()

void ns3::TcpCubic::IncreaseWindow	(	Ptr< TcpSocketState >	tcb,
		uint32_t	segmentsAcked
	)

overridevirtual

Congestion avoidance algorithm implementation.

Mimic the function cong_avoid in Linux. New segments have been ACKed, and the congestion control duty is to update the window.

The function is allowed to change directly cWnd and/or ssThresh.

Parameters

tcb	internal congestion state
segmentsAcked	count of segments acked

Reimplemented from ns3::TcpCongestionOps.

Definition at line 188 of file tcp-cubic.cc.

References HystartReset(), m_cWndCnt, m_endSeq, m_hystart, NS_LOG_FUNCTION, NS_LOG_INFO, and Update().

Here is the call graph for this function:

◆ PktsAcked()

void ns3::TcpCubic::PktsAcked	(	Ptr< TcpSocketState >	tcb,
		uint32_t	segmentsAcked,
		const Time &	rtt
	)

overridevirtual

Timing information on received ACK.

The function is called every time an ACK is received (only one time also for cumulative ACKs) and contains timing information. It is optional (congestion controls need not implement it) and the default implementation does nothing.

Parameters

tcb	internal congestion state
segmentsAcked	count of segments acked
rtt	last rtt

Reimplemented from ns3::TcpCongestionOps.

Definition at line 350 of file tcp-cubic.cc.

References HystartUpdate(), m_cubicDelta, m_delayMin, m_epochStart, m_hystart, m_hystartLowWindow, ns3::Time::Min(), ns3::Simulator::Now(), and NS_LOG_FUNCTION.

Here is the call graph for this function:

◆ Update()

uint32_t ns3::TcpCubic::Update	(	Ptr< TcpSocketState >	tcb,
		uint32_t	segmentsAcked
	)

private

Cubic window update after a new ack received.

Parameters

tcb	Transmission Control Block of the connection
segmentsAcked	Segments acked

Returns: the congestion window update counter

Definition at line 240 of file tcp-cubic.cc.

References ns3::Time::GetSeconds(), m_ackCnt, m_beta, m_bicK, m_bicOriginPoint, m_c, m_cntClamp, m_delayMin, m_epochStart, m_lastMaxCwnd, m_tcpCwnd, m_tcpFriendliness, ns3::Time::Min(), ns3::Simulator::Now(), NS_LOG_DEBUG, and NS_LOG_FUNCTION.

Referenced by IncreaseWindow().

Here is the call graph for this function:

Here is the caller graph for this function:

Member Data Documentation

◆ m_ackCnt

uint32_t ns3::TcpCubic::m_ackCnt

private

Count the number of ACKed packets.

Definition at line 138 of file tcp-cubic.h.

Referenced by CubicReset(), and Update().

◆ m_beta

double ns3::TcpCubic::m_beta

private

Beta for cubic multiplicative increase.

Definition at line 108 of file tcp-cubic.h.

Referenced by GetSsThresh(), GetTypeId(), and Update().

◆ m_bicK

double ns3::TcpCubic::m_bicK

private

Time to origin point from the beginning.

Definition at line 127 of file tcp-cubic.h.

Referenced by CubicReset(), and Update().

◆ m_bicOriginPoint

uint32_t ns3::TcpCubic::m_bicOriginPoint

private

Origin point of bic function.

Definition at line 126 of file tcp-cubic.h.

Referenced by CubicReset(), and Update().

◆ m_c

double ns3::TcpCubic::m_c

private

Cubic Scaling factor.

Definition at line 121 of file tcp-cubic.h.

Referenced by GetTypeId(), and Update().

◆ m_cntClamp

uint8_t ns3::TcpCubic::m_cntClamp

private

Modulo of the (avoided) float division for cWnd.

Definition at line 119 of file tcp-cubic.h.

Referenced by GetTypeId(), and Update().

◆ m_cubicDelta

Time ns3::TcpCubic::m_cubicDelta

private

Time to wait after recovery before update.

Definition at line 135 of file tcp-cubic.h.

Referenced by GetTypeId(), and PktsAcked().

◆ m_currRtt

Time ns3::TcpCubic::m_currRtt

private

Current Rtt.

Definition at line 136 of file tcp-cubic.h.

Referenced by HystartReset(), and HystartUpdate().

◆ m_cWndCnt

uint32_t ns3::TcpCubic::m_cWndCnt

private

cWnd integer-to-float counter

Definition at line 124 of file tcp-cubic.h.

Referenced by IncreaseWindow().

◆ m_delayMin

Time ns3::TcpCubic::m_delayMin

private

Min delay.

Definition at line 129 of file tcp-cubic.h.

Referenced by CubicReset(), HystartUpdate(), PktsAcked(), and Update().

◆ m_endSeq

SequenceNumber32 ns3::TcpCubic::m_endSeq

private

End sequence of the round.

Definition at line 133 of file tcp-cubic.h.

Referenced by HystartReset(), and IncreaseWindow().

◆ m_epochStart

Time ns3::TcpCubic::m_epochStart

private

Beginning of an epoch.

Definition at line 130 of file tcp-cubic.h.

Referenced by GetSsThresh(), PktsAcked(), and Update().

◆ m_fastConvergence

bool ns3::TcpCubic::m_fastConvergence

private

Enable or disable fast convergence algorithm.

Definition at line 106 of file tcp-cubic.h.

Referenced by GetSsThresh(), and GetTypeId().

◆ m_found

bool ns3::TcpCubic::m_found

private

The exit point is found?

Definition at line 131 of file tcp-cubic.h.

Referenced by CubicReset(), and HystartUpdate().

◆ m_hystart

bool ns3::TcpCubic::m_hystart

private

Enable or disable HyStart algorithm.

Definition at line 110 of file tcp-cubic.h.

Referenced by GetTypeId(), IncreaseWindow(), and PktsAcked().

◆ m_hystartAckDelta

Time ns3::TcpCubic::m_hystartAckDelta

private

Spacing between ack's indicating train.

Definition at line 113 of file tcp-cubic.h.

Referenced by GetTypeId(), and HystartUpdate().

◆ m_hystartDelayMax

Time ns3::TcpCubic::m_hystartDelayMax

private

Maximum time for hystart algorithm.

Definition at line 115 of file tcp-cubic.h.

Referenced by GetTypeId(), and HystartDelayThresh().

◆ m_hystartDelayMin

Time ns3::TcpCubic::m_hystartDelayMin

private

Minimum time for hystart algorithm.

Definition at line 114 of file tcp-cubic.h.

Referenced by GetTypeId(), and HystartDelayThresh().

◆ m_hystartDetect

HybridSSDetectionMode ns3::TcpCubic::m_hystartDetect

private

Detect way for HyStart algorithm.

Definition at line 111 of file tcp-cubic.h.

Referenced by GetTypeId(), and HystartUpdate().

◆ m_hystartLowWindow

uint32_t ns3::TcpCubic::m_hystartLowWindow

private

Lower bound cWnd for hybrid slow start (segments)

Definition at line 112 of file tcp-cubic.h.

Referenced by GetTypeId(), and PktsAcked().

◆ m_hystartMinSamples

uint8_t ns3::TcpCubic::m_hystartMinSamples

private

Number of delay samples for detecting the increase of delay.

Definition at line 116 of file tcp-cubic.h.

Referenced by GetTypeId(), and HystartUpdate().

◆ m_initialCwnd

uint32_t ns3::TcpCubic::m_initialCwnd

private

Initial cWnd.

Definition at line 118 of file tcp-cubic.h.

◆ m_lastAck

Time ns3::TcpCubic::m_lastAck

private

Last time when the ACK spacing is close.

Definition at line 134 of file tcp-cubic.h.

Referenced by HystartReset(), and HystartUpdate().

◆ m_lastMaxCwnd

uint32_t ns3::TcpCubic::m_lastMaxCwnd

private

Last maximum cWnd.

Definition at line 125 of file tcp-cubic.h.

Referenced by CubicReset(), GetSsThresh(), and Update().

◆ m_roundStart

Time ns3::TcpCubic::m_roundStart

private

Beginning of each round.

Definition at line 132 of file tcp-cubic.h.

Referenced by HystartReset(), and HystartUpdate().

◆ m_sampleCnt

uint32_t ns3::TcpCubic::m_sampleCnt

private

Count of samples for HyStart.

Definition at line 137 of file tcp-cubic.h.

Referenced by HystartReset(), and HystartUpdate().

◆ m_tcpCwnd

uint32_t ns3::TcpCubic::m_tcpCwnd

private

Estimated tcp cwnd (for Reno-friendliness)

Definition at line 139 of file tcp-cubic.h.

Referenced by CubicReset(), and Update().

◆ m_tcpFriendliness

bool ns3::TcpCubic::m_tcpFriendliness

private

Enable or disable TCP-friendliness heuristic.

Definition at line 107 of file tcp-cubic.h.

Referenced by GetTypeId(), and Update().

The documentation for this class was generated from the following files:

src/internet/model/tcp-cubic.h
src/internet/model/tcp-cubic.cc

Public Types

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Config Paths

Attributes

Attributes defined in parent class ns3::TcpSocketBase

Attributes defined in parent class ns3::TcpSocket

TraceSources defined in parent class ns3::TcpSocketBase

Member Enumeration Documentation

◆ HybridSSDetectionMode

Constructor & Destructor Documentation

◆ TcpCubic() [1/2]

◆ TcpCubic() [2/2]

Member Function Documentation

◆ CongestionStateSet()

◆ CubicReset()

◆ Fork()

◆ GetName()

◆ GetSsThresh()

◆ GetTypeId()

◆ HystartDelayThresh()

◆ HystartReset()

◆ HystartUpdate()

◆ IncreaseWindow()

◆ PktsAcked()

◆ Update()

Member Data Documentation

◆ m_ackCnt

◆ m_beta

◆ m_bicK

◆ m_bicOriginPoint

◆ m_c

◆ m_cntClamp

◆ m_cubicDelta

◆ m_currRtt

◆ m_cWndCnt

◆ m_delayMin

◆ m_endSeq

◆ m_epochStart

◆ m_fastConvergence

◆ m_found

◆ m_hystart

◆ m_hystartAckDelta

◆ m_hystartDelayMax

◆ m_hystartDelayMin

◆ m_hystartDetect

◆ m_hystartLowWindow

◆ m_hystartMinSamples

◆ m_initialCwnd

◆ m_lastAck

◆ m_lastMaxCwnd

◆ m_roundStart

◆ m_sampleCnt

◆ m_tcpCwnd

◆ m_tcpFriendliness