An implementation of TCP YeAH. More...

#include "tcp-yeah.h"

Inheritance diagram for ns3::TcpYeah:

Collaboration diagram for ns3::TcpYeah:

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

	TcpYeah (const TcpYeah &sock)
	Copy constructor.

	~TcpYeah () override

void	CongestionStateSet (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCongState_t newState) override
	Enable/disable YeAH algorithm depending on the 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 slow start threshold upon the receipt of 3 dupACKs.

void	IncreaseWindow (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override
	Adjust cwnd following YeAH dual-mode algorithm.

void	PktsAcked (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked, const Time &rtt) override
	Compute RTTs needed to execute YeAH algorithm.

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

	TcpNewReno (const TcpNewReno &sock)
	Copy constructor.

	~TcpNewReno () override

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	DisableYeah ()
	Stop taking YeAH samples.

void	EnableYeah (const SequenceNumber32 &nextTxSequence)
	Enable YeAH algorithm to start taking YeAH samples.

Private Attributes
uint32_t	m_alpha
	Maximum backlog allowed at the bottleneck queue; Q_max in the paper.

Time	m_baseRtt
	Minimum of all YeAH RTT measurements seen during connection.

SequenceNumber32	m_begSndNxt
	Right edge during last RTT.

uint32_t	m_cntRtt
	Number of RTT measurements during last RTT.

uint32_t	m_delta
	Log minimum fraction of cwnd to be removed on loss.

uint32_t	m_doingRenoNow
	Number of RTTs in "Slow" mode.

bool	m_doingYeahNow
	If true, do YeAH for this RTT.

uint32_t	m_epsilon
	Log maximum fraction to be removed on early decongestion.

uint32_t	m_fastCount
	Number of RTTs in "Fast" mode.

uint32_t	m_gamma
	Fraction of queue to be removed per RTT when precautionary decongestion executed.

uint32_t	m_lastQ
	Last number of packets in the bottleneck queue.

Time	m_minRtt
	Minimum of all RTTs measured within last RTT.

uint32_t	m_phy
	Maximum delta from base.

uint32_t	m_renoCount
	Estimated cwnd of competing Reno flow.

uint32_t	m_rho
	Minimum number of consecutive RTT to consider competition with Reno flows on loss.

Ptr< TcpScalable >	m_stcp
	TcpScalable object.

uint32_t	m_stcpAiFactor
	STCP additive increase parameter.

uint32_t	m_zeta
	Minimum number of state switches to reset m_renoCount.

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 YeAH.

YeAH-TCP (Yet Another HighSpeed TCP) is a heuristic designed to balance various requirements of a state-of-the-art congestion control algorithm: 1) fully exploit the link capacity of high BDP networks while inducing a small number of congestion events 2) compete friendly with Reno flows 3) achieve intra and RTT fairness 4) robust to random losses 5) achieve high performance regardless of buffer size

YeAH operates between 2 modes: Fast and Slow mode. In the Fast mode when the queue occupancy is small and the network congestion level is low, YeAH increments its congestion window according to the aggressive STCP rule. When the number of packets in the queue grows beyond a threshold and the network congestion level is high, YeAH enters its Slow mode, acting as Reno with a decongestion algorithm. YeAH employs Vegas' mechanism for calculating the backlog as in Equation (1). The estimation of the network congestion level is shown in Equation (2).

                 Q = (RTT - BaseRTT) (cwnd / RTT)    (1)
                 L = (RTT - BaseRTT) / BaseRTT       (2)

To ensure TCP friendliness, YeAH also implements an algorithm to detect the presence of legacy Reno flows. Upon the receipt of 3 duplicate ACKs, YeAH decreases its slow start threshold according to Equation (3) if it's not competing with Reno flows. Otherwise, the ssthresh is halved as in Reno.

                 ssthresh = min{max{cwnd/8, Q}, cwnd/2}

More information: http://www.csc.lsu.edu/~sjpark/cs7601/4-YeAH_TCP.pdf

Definition at line 61 of file tcp-yeah.h.

Constructor & Destructor Documentation

◆ TcpYeah() [1/2]

ns3::TcpYeah::TcpYeah ( )

Create an unbound tcp socket.

Definition at line 76 of file tcp-yeah.cc.

References ns3::CreateObject(), m_stcp, m_stcpAiFactor, and NS_LOG_FUNCTION.

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◆ TcpYeah() [2/2]

ns3::TcpYeah::TcpYeah ( const TcpYeah & sock )

Copy constructor.

Parameters

sock	the object to copy

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

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

◆ ~TcpYeah()

ns3::TcpYeah::~TcpYeah ( )

override

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

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CongestionStateSet()

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

overridevirtual

Enable/disable YeAH algorithm depending on the congestion state.

We only start a YeAH cycle when we are in normal congestion state (CA_OPEN state).

Parameters

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

Reimplemented from ns3::TcpCongestionOps.

Definition at line 178 of file tcp-yeah.cc.

References ns3::TcpSocketState::CA_OPEN, DisableYeah(), EnableYeah(), and NS_LOG_FUNCTION.

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◆ DisableYeah()

void ns3::TcpYeah::DisableYeah ( )

private

Stop taking YeAH samples.

Definition at line 170 of file tcp-yeah.cc.

References m_doingYeahNow, and NS_LOG_FUNCTION.

Referenced by CongestionStateSet().

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◆ EnableYeah()

void ns3::TcpYeah::EnableYeah ( const SequenceNumber32 & nextTxSequence )

private

Enable YeAH algorithm to start taking YeAH samples.

YeAH algorithm is enabled in the following situations:

at the establishment of a connection
after an RTO
after fast recovery
when an idle connection is restarted

Parameters

nextTxSequence Sequence to transmit next

Definition at line 159 of file tcp-yeah.cc.

References m_begSndNxt, m_cntRtt, m_doingYeahNow, m_minRtt, ns3::Time::Max(), and NS_LOG_FUNCTION.

Referenced by CongestionStateSet().

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◆ Fork()

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

overridevirtual

Copy the congestion control algorithm across sockets.

Returns: a pointer of the copied object

Reimplemented from ns3::TcpNewReno.

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

References ns3::Object::CopyObject.

◆ GetName()

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

overridevirtual

Get the name of the congestion control algorithm.

Returns: A string identifying the name

Reimplemented from ns3::TcpNewReno.

Definition at line 304 of file tcp-yeah.cc.

◆ GetSsThresh()

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

overridevirtual

Get slow start threshold upon the receipt of 3 dupACKs.

Parameters

tcb	internal congestion state
bytesInFlight	number of outstanding bytes

Returns: the slow start threshold value

Reimplemented from ns3::TcpNewReno.

Definition at line 310 of file tcp-yeah.cc.

References m_delta, m_doingRenoNow, m_fastCount, m_lastQ, m_renoCount, m_rho, NS_LOG_FUNCTION, NS_LOG_INFO, and NS_LOG_LOGIC.

◆ GetTypeId()

TypeId ns3::TcpYeah::GetTypeId ( )

static

Get the type ID.

Returns: the object TypeId

Definition at line 26 of file tcp-yeah.cc.

References m_alpha, m_delta, m_epsilon, m_gamma, m_phy, m_rho, m_stcpAiFactor, m_zeta, ns3::MakeUintegerAccessor(), ns3::MakeUintegerChecker(), and ns3::TypeId::SetParent().

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◆ IncreaseWindow()

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

overridevirtual

Adjust cwnd following YeAH dual-mode algorithm.

Parameters

tcb	internal congestion state
segmentsAcked	count of segments ACKed

Reimplemented from ns3::TcpNewReno.

Definition at line 193 of file tcp-yeah.cc.

References ns3::TcpNewReno::CongestionAvoidance(), ns3::Time::GetMilliSeconds(), ns3::Time::GetSeconds(), m_alpha, m_baseRtt, m_begSndNxt, m_cntRtt, m_doingRenoNow, m_epsilon, m_fastCount, m_gamma, m_lastQ, m_minRtt, m_phy, m_renoCount, m_stcp, m_zeta, ns3::Time::Max(), NS_ASSERT, NS_LOG_DEBUG, NS_LOG_FUNCTION, NS_LOG_INFO, NS_LOG_LOGIC, and ns3::TcpNewReno::SlowStart().

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◆ PktsAcked()

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

overridevirtual

Compute RTTs needed to execute YeAH algorithm.

The function filters RTT samples from the last RTT to find the current smallest propagation delay + queueing delay (minRtt). We take the minimum to avoid the effects of delayed ACKs.

The function also min-filters all RTT measurements seen to find the propagation delay (baseRtt).

Parameters

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

Reimplemented from ns3::TcpCongestionOps.

Definition at line 138 of file tcp-yeah.cc.

References ns3::Time::GetMilliSeconds(), ns3::Time::IsZero(), m_baseRtt, m_cntRtt, m_minRtt, NS_LOG_DEBUG, and NS_LOG_FUNCTION.

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Member Data Documentation

◆ m_alpha

uint32_t ns3::TcpYeah::m_alpha

private

Maximum backlog allowed at the bottleneck queue; Q_max in the paper.

Definition at line 153 of file tcp-yeah.h.

Referenced by GetTypeId(), and IncreaseWindow().

◆ m_baseRtt

Time ns3::TcpYeah::m_baseRtt

private

Minimum of all YeAH RTT measurements seen during connection.

Definition at line 165 of file tcp-yeah.h.

Referenced by IncreaseWindow(), and PktsAcked().

◆ m_begSndNxt

SequenceNumber32 ns3::TcpYeah::m_begSndNxt

private

Right edge during last RTT.

Definition at line 169 of file tcp-yeah.h.

Referenced by EnableYeah(), and IncreaseWindow().

◆ m_cntRtt

uint32_t ns3::TcpYeah::m_cntRtt

private

Number of RTT measurements during last RTT.

Definition at line 167 of file tcp-yeah.h.

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

◆ m_delta

uint32_t ns3::TcpYeah::m_delta

private

Log minimum fraction of cwnd to be removed on loss.

Definition at line 156 of file tcp-yeah.h.

Referenced by GetSsThresh(), and GetTypeId().

◆ m_doingRenoNow

uint32_t ns3::TcpYeah::m_doingRenoNow

private

Number of RTTs in "Slow" mode.

Definition at line 171 of file tcp-yeah.h.

Referenced by GetSsThresh(), and IncreaseWindow().

◆ m_doingYeahNow

bool ns3::TcpYeah::m_doingYeahNow

private

If true, do YeAH for this RTT.

Definition at line 168 of file tcp-yeah.h.

Referenced by DisableYeah(), and EnableYeah().

◆ m_epsilon

uint32_t ns3::TcpYeah::m_epsilon

private

Log maximum fraction to be removed on early decongestion.

Definition at line 157 of file tcp-yeah.h.

Referenced by GetTypeId(), and IncreaseWindow().

◆ m_fastCount

uint32_t ns3::TcpYeah::m_fastCount

private

Number of RTTs in "Fast" mode.

Definition at line 173 of file tcp-yeah.h.

Referenced by GetSsThresh(), and IncreaseWindow().

◆ m_gamma

uint32_t ns3::TcpYeah::m_gamma

private

Fraction of queue to be removed per RTT when precautionary decongestion executed.

Definition at line 154 of file tcp-yeah.h.

Referenced by GetTypeId(), and IncreaseWindow().

◆ m_lastQ

uint32_t ns3::TcpYeah::m_lastQ

private

Last number of packets in the bottleneck queue.

Definition at line 170 of file tcp-yeah.h.

Referenced by GetSsThresh(), and IncreaseWindow().

◆ m_minRtt

Time ns3::TcpYeah::m_minRtt

private

Minimum of all RTTs measured within last RTT.

Definition at line 166 of file tcp-yeah.h.

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

◆ m_phy

uint32_t ns3::TcpYeah::m_phy

private

Maximum delta from base.

Definition at line 158 of file tcp-yeah.h.

Referenced by GetTypeId(), and IncreaseWindow().

◆ m_renoCount

uint32_t ns3::TcpYeah::m_renoCount

private

Estimated cwnd of competing Reno flow.

Definition at line 172 of file tcp-yeah.h.

Referenced by GetSsThresh(), and IncreaseWindow().

◆ m_rho

uint32_t ns3::TcpYeah::m_rho

private

Minimum number of consecutive RTT to consider competition with Reno flows on loss.

Definition at line 159 of file tcp-yeah.h.

Referenced by GetSsThresh(), and GetTypeId().

◆ m_stcp

Ptr<TcpScalable> ns3::TcpYeah::m_stcp

private

TcpScalable object.

Definition at line 164 of file tcp-yeah.h.

Referenced by TcpYeah(), TcpYeah(), and IncreaseWindow().

◆ m_stcpAiFactor

uint32_t ns3::TcpYeah::m_stcpAiFactor

private

STCP additive increase parameter.

Definition at line 163 of file tcp-yeah.h.

Referenced by TcpYeah(), and GetTypeId().

◆ m_zeta

uint32_t ns3::TcpYeah::m_zeta

private

Minimum number of state switches to reset m_renoCount.

Definition at line 161 of file tcp-yeah.h.

Referenced by GetTypeId(), and IncreaseWindow().

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

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

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ TcpYeah() [1/2]

◆ TcpYeah() [2/2]

◆ ~TcpYeah()

Member Function Documentation

◆ CongestionStateSet()

◆ DisableYeah()

◆ EnableYeah()

◆ Fork()

◆ GetName()

◆ GetSsThresh()

◆ GetTypeId()

◆ IncreaseWindow()

◆ PktsAcked()

Member Data Documentation

◆ m_alpha

◆ m_baseRtt

◆ m_begSndNxt

◆ m_cntRtt

◆ m_delta

◆ m_doingRenoNow

◆ m_doingYeahNow

◆ m_epsilon

◆ m_fastCount

◆ m_gamma

◆ m_lastQ

◆ m_minRtt

◆ m_phy

◆ m_renoCount

◆ m_rho

◆ m_stcp

◆ m_stcpAiFactor

◆ m_zeta