An implementation of TCP Illinois algorithm. More...

#include "tcp-illinois.h"

Inheritance diagram for ns3::TcpIllinois:

Collaboration diagram for ns3::TcpIllinois:

Public Member Functions
	TcpIllinois ()
	Create an unbound tcp socket.

	TcpIllinois (const TcpIllinois &sock)
	Copy constructor.

	~TcpIllinois () override

void	CongestionStateSet (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCongState_t newState) override
	Reset Illinois parameters to default values upon a loss.

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 slow start threshold after congestion event.

void	IncreaseWindow (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override
	Adjust cwnd following Illinois congestion avoidance algorithm.

void	PktsAcked (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked, const Time &rtt) override
	Measure RTT for each ACK Keep track of min and max RTT.

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

	TcpNewReno (const TcpNewReno &sock)
	Copy constructor.

	~TcpNewReno () override

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
	Try to increase the cWnd following the NewReno specification.

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

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

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

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, bool permissive=false) 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.

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::TcpNewReno
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	CalculateAlpha (double da, double dm)
	Calculate additive increase factor alpha.

Time	CalculateAvgDelay () const
	Calculate average queueing delay.

void	CalculateBeta (double da, double dm)
	Calculate multiplicative decrease factor beta.

Time	CalculateMaxDelay () const
	Calculate maximum queueing delay.

void	RecalcParam (uint32_t cWnd)
	Recalculate alpha and beta every RTT.

void	Reset (const SequenceNumber32 &nextTxSequence)
	Reset Illinois parameters.

Private Attributes
uint32_t	m_ackCnt
	Number of received ACK.

double	m_alpha
	Additive increase factor.

double	m_alphaBase
	Base value of alpha for standard AIMD.

double	m_alphaMax
	Maximum alpha threshold.

double	m_alphaMin
	Minimum alpha threshold.

Time	m_baseRtt
	Minimum of all RTT measurements.

double	m_beta
	Multiplicative decrease factor.

double	m_betaBase
	Base value of beta for standard AIMD.

double	m_betaMax
	Maximum beta threshold.

double	m_betaMin
	Minimum beta threshold.

uint32_t	m_cntRtt
	Number of RTT measurements during last RTT.

SequenceNumber32	m_endSeq
	Right edge of current RTT.

Time	m_maxRtt
	Maximum of all RTT measurements.

bool	m_rttAbove
	True when da > d1.

uint8_t	m_rttLow
	Number of RTTs da has stayed below d1.

Time	m_sumRtt
	Sum of all RTT measurements during last RTT.

uint32_t	m_theta
	Number of RTTs required before setting alpha to its max.

uint32_t	m_winThresh
	Window threshold for adaptive sizing.

Additional Inherited Members
Protected Member Functions inherited from ns3::TcpNewReno
virtual void	CongestionAvoidance (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
	NewReno congestion avoidance.

virtual uint32_t	SlowStart (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
	Tcp NewReno slow start algorithm.

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

Detailed Description

An implementation of TCP Illinois algorithm.

TCP Illinois is a hybrid congestion control algorithm designed for high-speed networks. Illinois implements a Concave-AIMD (or C-AIMD) algorithm that uses packet loss as the primary congestion signal to determine the direction of window update and queueing delay as the secondary congestion signal to determine the amount of change.

The additive increase and multiplicative decrease factors (denoted as alpha and beta, respectively) are functions of the current average queueing delay da as shown in Equations (1) and (2). To improve the protocol robustness against sudden fluctuations in its delay sampling, Illinois allows the increment of alpha to alphaMax only if da stays below d1 for a some (theta) amount of time.

                         / alphaMax          if da <= d1
                 alpha =                                         (1)
                         \ k1 / (k2 + da)    otherwise

                        / betaMin            if da <= d2
                 beta =   k3 + k4da          if d2 < da < d3      (2)
                        \ betaMax            otherwise

where the calculations of k1, k2, k3, and k4 are shown in Equations (3), (4), (5), and (6).

     k1 = (dm - d1)(alphaMin)alphaMax / (alphaMax - alphaMin)    (3)

     k2 = ((dm - d1)alphaMin / (alphaMax - alphaMin)) - d1       (4)

     k3 = ((alphaMin)d3 - (alphaMax)d2) / (d3 - d2)              (5)

     k4 = (alphaMax - alphaMin) / (d3 - d2)                      (6)

with da the current average queueing delay calculated in Equation (7) where: Ta is the average RTT (sumRtt / cntRtt in the implementation) and Tmin (baseRtt in the implementation) is the minimum RTT ever seen dm the maximum (average) queueing delay calculated in Equation (8) where Tmax (maxRtt in the implementation) is the maximum RTT ever seen

     da = Ta - Tmin          (7)

     dm = Tmax - Tmin         (8)

di (i = 1,2,3) are calculated in Equation (9) (0 <= eta_1 < 1, and 0 <= eta_2 <= eta_3 <=1)

      di = (eta_i)dm            (9)

Illinois only executes its adaptation of alpha and beta when cwnd exceeds a threshold called winThresh. Otherwise, it sets alpha and beta to the base values of 1 and 0.5, respectively.

Following the implementation of Illinois in the Linux kernel, we use the following default parameter settings:

  alphaMin = 0.3      (0.1 in the Illinois paper)
  alphaMax = 10.0
  betaMin = 0.125
  betaMax = 0.5
  winThresh = 15      (10 in the Illinois paper)
  theta = 5
  eta1 = 0.01
  eta2 = 0.1
  eta3 = 0.8

More information: http://www.doi.org/10.1145/1190095.1190166

Definition at line 97 of file tcp-illinois.h.

Constructor & Destructor Documentation

◆ TcpIllinois() [1/2]

ns3::TcpIllinois::TcpIllinois ( )

Create an unbound tcp socket.

Definition at line 78 of file tcp-illinois.cc.

References NS_LOG_FUNCTION.

◆ TcpIllinois() [2/2]

ns3::TcpIllinois::TcpIllinois ( const TcpIllinois & sock )

Copy constructor.

Parameters

sock	the object to copy

Definition at line 102 of file tcp-illinois.cc.

References NS_LOG_FUNCTION.

◆ ~TcpIllinois()

ns3::TcpIllinois::~TcpIllinois ( )

override

Definition at line 126 of file tcp-illinois.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CalculateAlpha()

void ns3::TcpIllinois::CalculateAlpha	(	double	da,
		double	dm )

private

Calculate additive increase factor alpha.

If average queueing delay is at minimum, then alpha is set to alphaMax. Otherwise, alpha is a decreasing function of average queueing delay.

Parameters

da	current average queueing delay
dm	maximum average queueing delay

Definition at line 250 of file tcp-illinois.cc.

References m_alpha, m_alphaMax, m_alphaMin, m_rttAbove, m_rttLow, m_theta, NS_LOG_FUNCTION, and NS_LOG_INFO.

Referenced by RecalcParam().

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◆ CalculateAvgDelay()

Time ns3::TcpIllinois::CalculateAvgDelay ( ) const

private

Calculate average queueing delay.

Returns: average queueing delay da

Definition at line 337 of file tcp-illinois.cc.

References m_baseRtt, m_cntRtt, m_sumRtt, and NS_LOG_FUNCTION.

Referenced by RecalcParam().

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◆ CalculateBeta()

void ns3::TcpIllinois::CalculateBeta	(	double	da,
		double	dm )

private

Calculate multiplicative decrease factor beta.

If the current average queueing delay is <= 10% of max. (average) queueing delay, beta is set to betaMin, which equals to 1/8 by default. If the current average queueing delay is >= 80% of max. (average) queueing delay, beta is set to betaMax, which equals to 1/2 by default. Otherwise, beta is an increasing function of average queueing delay.

Parameters

da	current average queueing delay
dm	maximum average queueing delay

Definition at line 297 of file tcp-illinois.cc.

References m_beta, m_betaMax, m_betaMin, NS_LOG_FUNCTION, and NS_LOG_INFO.

Referenced by RecalcParam().

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◆ CalculateMaxDelay()

Time ns3::TcpIllinois::CalculateMaxDelay ( ) const

private

Calculate maximum queueing delay.

Returns: maximum average queueing delay dm

Definition at line 345 of file tcp-illinois.cc.

References m_baseRtt, m_maxRtt, and NS_LOG_FUNCTION.

Referenced by RecalcParam().

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◆ CongestionStateSet()

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

overridevirtual

Reset Illinois parameters to default values upon a loss.

Parameters

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

Reimplemented from ns3::TcpCongestionOps.

Definition at line 156 of file tcp-illinois.cc.

References ns3::TcpSocketState::CA_LOSS, m_alpha, m_alphaBase, m_beta, m_betaBase, m_rttAbove, m_rttLow, NS_LOG_FUNCTION, and Reset().

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◆ Fork()

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

overridevirtual

Copy the congestion control algorithm across sockets.

Returns: a pointer of the copied object

Implements ns3::TcpCongestionOps.

Definition at line 363 of file tcp-illinois.cc.

References ns3::Object::CopyObject, and NS_LOG_FUNCTION.

◆ GetName()

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

overridevirtual

Get the name of the congestion control algorithm.

Returns: A string identifying the name

Implements ns3::TcpCongestionOps.

Definition at line 371 of file tcp-illinois.cc.

References NS_LOG_FUNCTION.

◆ GetSsThresh()

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

overridevirtual

Get slow start threshold after congestion event.

Parameters

tcb	internal congestion state
bytesInFlight	bytes in flight

Returns: the slow start threshold value

Implements ns3::TcpCongestionOps.

Definition at line 237 of file tcp-illinois.cc.

References m_beta, NS_LOG_DEBUG, and NS_LOG_FUNCTION.

◆ GetTypeId()

TypeId ns3::TcpIllinois::GetTypeId ( )

static

Get the type ID.

Returns: the object TypeId

Definition at line 29 of file tcp-illinois.cc.

References m_alphaBase, m_alphaMax, m_alphaMin, m_betaBase, m_betaMax, m_betaMin, m_theta, m_winThresh, ns3::MakeDoubleAccessor(), ns3::MakeDoubleChecker(), ns3::MakeUintegerAccessor(), ns3::MakeUintegerChecker(), and ns3::TypeId::SetParent().

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◆ IncreaseWindow()

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

overridevirtual

Adjust cwnd following Illinois congestion avoidance algorithm.

Parameters

tcb	internal congestion state
segmentsAcked	count of segments ACKed

Reimplemented from ns3::TcpCongestionOps.

Definition at line 172 of file tcp-illinois.cc.

References m_ackCnt, m_alpha, m_endSeq, NS_LOG_FUNCTION, NS_LOG_INFO, RecalcParam(), Reset(), and ns3::TcpNewReno::SlowStart().

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◆ PktsAcked()

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

overridevirtual

Measure RTT for each ACK Keep track of min and max RTT.

Parameters

tcb	internal congestion state
segmentsAcked	count of segments ACKed
rtt	last RTT

Reimplemented from ns3::TcpCongestionOps.

Definition at line 214 of file tcp-illinois.cc.

References ns3::Time::IsZero(), m_baseRtt, m_cntRtt, m_maxRtt, m_sumRtt, NS_LOG_FUNCTION, and NS_LOG_INFO.

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◆ RecalcParam()

void ns3::TcpIllinois::RecalcParam ( uint32_t cWnd )

private

Recalculate alpha and beta every RTT.

Parameters

cWnd	current Cwnd (in bytes)

Definition at line 132 of file tcp-illinois.cc.

References CalculateAlpha(), CalculateAvgDelay(), CalculateBeta(), CalculateMaxDelay(), ns3::Time::GetMilliSeconds(), m_alpha, m_alphaBase, m_beta, m_betaBase, m_cntRtt, m_winThresh, NS_LOG_FUNCTION, and NS_LOG_INFO.

Referenced by IncreaseWindow().

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◆ Reset()

void ns3::TcpIllinois::Reset ( const SequenceNumber32 & nextTxSequence )

private

Reset Illinois parameters.

Parameters

nextTxSequence Next sequence to transmit

Definition at line 353 of file tcp-illinois.cc.

References m_cntRtt, m_endSeq, m_sumRtt, and NS_LOG_FUNCTION.

Referenced by CongestionStateSet(), and IncreaseWindow().

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Member Data Documentation

◆ m_ackCnt

uint32_t ns3::TcpIllinois::m_ackCnt

private

Number of received ACK.

Definition at line 234 of file tcp-illinois.h.

Referenced by IncreaseWindow().

◆ m_alpha

double ns3::TcpIllinois::m_alpha

private

Additive increase factor.

Definition at line 227 of file tcp-illinois.h.

Referenced by CalculateAlpha(), CongestionStateSet(), IncreaseWindow(), and RecalcParam().

◆ m_alphaBase

double ns3::TcpIllinois::m_alphaBase

private

Base value of alpha for standard AIMD.

Definition at line 226 of file tcp-illinois.h.

Referenced by CongestionStateSet(), GetTypeId(), and RecalcParam().

◆ m_alphaMax

double ns3::TcpIllinois::m_alphaMax

private

Maximum alpha threshold.

Definition at line 225 of file tcp-illinois.h.

Referenced by CalculateAlpha(), and GetTypeId().

◆ m_alphaMin

double ns3::TcpIllinois::m_alphaMin

private

Minimum alpha threshold.

Definition at line 224 of file tcp-illinois.h.

Referenced by CalculateAlpha(), and GetTypeId().

◆ m_baseRtt

Time ns3::TcpIllinois::m_baseRtt

private

Minimum of all RTT measurements.

Definition at line 219 of file tcp-illinois.h.

Referenced by CalculateAvgDelay(), CalculateMaxDelay(), and PktsAcked().

◆ m_beta

double ns3::TcpIllinois::m_beta

private

Multiplicative decrease factor.

Definition at line 231 of file tcp-illinois.h.

Referenced by CalculateBeta(), CongestionStateSet(), GetSsThresh(), and RecalcParam().

◆ m_betaBase

double ns3::TcpIllinois::m_betaBase

private

Base value of beta for standard AIMD.

Definition at line 230 of file tcp-illinois.h.

Referenced by CongestionStateSet(), GetTypeId(), and RecalcParam().

◆ m_betaMax

double ns3::TcpIllinois::m_betaMax

private

Maximum beta threshold.

Definition at line 229 of file tcp-illinois.h.

Referenced by CalculateBeta(), and GetTypeId().

◆ m_betaMin

double ns3::TcpIllinois::m_betaMin

private

Minimum beta threshold.

Definition at line 228 of file tcp-illinois.h.

Referenced by CalculateBeta(), and GetTypeId().

◆ m_cntRtt

uint32_t ns3::TcpIllinois::m_cntRtt

private

Number of RTT measurements during last RTT.

Definition at line 218 of file tcp-illinois.h.

Referenced by CalculateAvgDelay(), PktsAcked(), RecalcParam(), and Reset().

◆ m_endSeq

SequenceNumber32 ns3::TcpIllinois::m_endSeq

private

Right edge of current RTT.

Definition at line 221 of file tcp-illinois.h.

Referenced by IncreaseWindow(), and Reset().

◆ m_maxRtt

Time ns3::TcpIllinois::m_maxRtt

private

Maximum of all RTT measurements.

Definition at line 220 of file tcp-illinois.h.

Referenced by CalculateMaxDelay(), and PktsAcked().

◆ m_rttAbove

bool ns3::TcpIllinois::m_rttAbove

private

True when da > d1.

Definition at line 222 of file tcp-illinois.h.

Referenced by CalculateAlpha(), and CongestionStateSet().

◆ m_rttLow

uint8_t ns3::TcpIllinois::m_rttLow

private

Number of RTTs da has stayed below d1.

Definition at line 223 of file tcp-illinois.h.

Referenced by CalculateAlpha(), and CongestionStateSet().

◆ m_sumRtt

Time ns3::TcpIllinois::m_sumRtt

private

Sum of all RTT measurements during last RTT.

Definition at line 217 of file tcp-illinois.h.

Referenced by CalculateAvgDelay(), PktsAcked(), and Reset().

◆ m_theta

uint32_t ns3::TcpIllinois::m_theta

private

Number of RTTs required before setting alpha to its max.

Definition at line 233 of file tcp-illinois.h.

Referenced by CalculateAlpha(), and GetTypeId().

◆ m_winThresh

uint32_t ns3::TcpIllinois::m_winThresh

private

Window threshold for adaptive sizing.

Definition at line 232 of file tcp-illinois.h.

Referenced by GetTypeId(), and RecalcParam().

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

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

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ TcpIllinois() [1/2]

◆ TcpIllinois() [2/2]

◆ ~TcpIllinois()

Member Function Documentation

◆ CalculateAlpha()

◆ CalculateAvgDelay()

◆ CalculateBeta()

◆ CalculateMaxDelay()

◆ CongestionStateSet()

◆ Fork()

◆ GetName()

◆ GetSsThresh()

◆ GetTypeId()

◆ IncreaseWindow()

◆ PktsAcked()

◆ RecalcParam()

◆ Reset()

Member Data Documentation

◆ m_ackCnt

◆ m_alpha

◆ m_alphaBase

◆ m_alphaMax

◆ m_alphaMin

◆ m_baseRtt

◆ m_beta

◆ m_betaBase

◆ m_betaMax

◆ m_betaMin

◆ m_cntRtt

◆ m_endSeq

◆ m_maxRtt

◆ m_rttAbove

◆ m_rttLow

◆ m_sumRtt

◆ m_theta

◆ m_winThresh