An implementation of TCP Veno. More...

#include "tcp-veno.h"

Inheritance diagram for ns3::TcpVeno:

Collaboration diagram for ns3::TcpVeno:

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

	TcpVeno (const TcpVeno &sock)
	Copy constructor.

	~TcpVeno () override

void	CongestionStateSet (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCongState_t newState) override
	Enable/disable Veno 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 during Veno multiplicative-decrease phase.

void	IncreaseWindow (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override
	Adjust cwnd following Veno additive increase algorithm.

void	PktsAcked (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked, const Time &rtt) override
	Perform RTT sampling needed to execute Veno 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	DisableVeno ()
	Turn off Veno.

void	EnableVeno ()
	Enable Veno algorithm to start Veno sampling.

Private Attributes
uint32_t	m_ackCnt
	Number of received ACK.

Time	m_baseRtt
	Minimum of all RTT measurements seen during connection.

uint32_t	m_beta
	Threshold for congestion detection.

uint32_t	m_cntRtt
	Number of RTT measurements during last RTT.

uint32_t	m_diff
	Difference between expected and actual throughput.

bool	m_doingVenoNow
	If true, do Veno for this RTT.

bool	m_inc
	If true, cwnd needs to be incremented.

Time	m_minRtt
	Minimum of RTTs measured within last RTT.

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 Veno.

TCP Veno enhances Reno algorithm for more effectively dealing with random packet loss in wireless access networks by employing Vegas's method in estimating the backlog at the bottleneck queue to distinguish between congestive and non-congestive states.

The backlog (the number of packets accumulated at the bottleneck queue) is calculated using Equation (1):

    N = Actual * (RTT - BaseRTT) = Diff * BaseRTT        (1)

where Diff = Expected - Actual = cwnd/BaseRTT - cwnd/RTT

Veno makes decision on cwnd modification based on the calculated N and its predefined threshold beta.

Specifically, it refines the additive increase algorithm of Reno so that the connection can stay longer in the stable state by incrementing cwnd by 1/cwnd for every other new ACK received after the available bandwidth has been fully utilized, i.e. when N exceeds beta. Otherwise, Veno increases its cwnd by 1/cwnd upon every new ACK receipt as in Reno.

In the multiplicative decrease algorithm, when Veno is in the non-congestive state, i.e. when N is less than beta, Veno decrements its cwnd by only 1/5 because the loss encountered is more likely a corruption-based loss than a congestion-based. Only when N is greater than beta, Veno halves its sending rate as in Reno.

More information: http://dx.doi.org/10.1109/JSAC.2002.807336

Definition at line 60 of file tcp-veno.h.

Constructor & Destructor Documentation

◆ TcpVeno() [1/2]

ns3::TcpVeno::TcpVeno ( )

Create an unbound tcp socket.

Definition at line 42 of file tcp-veno.cc.

References NS_LOG_FUNCTION.

◆ TcpVeno() [2/2]

ns3::TcpVeno::TcpVeno ( const TcpVeno & sock )

Copy constructor.

Parameters

sock	the object to copy

Definition at line 56 of file tcp-veno.cc.

References NS_LOG_FUNCTION.

◆ ~TcpVeno()

ns3::TcpVeno::~TcpVeno ( )

override

Definition at line 70 of file tcp-veno.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CongestionStateSet()

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

overridevirtual

Enable/disable Veno depending on the congestion state.

We only start a Veno 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 120 of file tcp-veno.cc.

References ns3::TcpSocketState::CA_OPEN, DisableVeno(), EnableVeno(), NS_LOG_FUNCTION, and NS_LOG_LOGIC.

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◆ DisableVeno()

void ns3::TcpVeno::DisableVeno ( )

private

Turn off Veno.

Definition at line 112 of file tcp-veno.cc.

References m_doingVenoNow, and NS_LOG_FUNCTION.

Referenced by CongestionStateSet().

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◆ EnableVeno()

void ns3::TcpVeno::EnableVeno ( )

private

Enable Veno algorithm to start Veno sampling.

Veno 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

Definition at line 103 of file tcp-veno.cc.

References m_doingVenoNow, m_minRtt, ns3::Time::Max(), and NS_LOG_FUNCTION.

Referenced by CongestionStateSet().

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◆ Fork()

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

overridevirtual

Copy the congestion control algorithm across sockets.

Returns: a pointer of the copied object

Reimplemented from ns3::TcpNewReno.

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

References ns3::Object::CopyObject.

◆ GetName()

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

overridevirtual

Get the name of the congestion control algorithm.

Returns: A string identifying the name

Reimplemented from ns3::TcpNewReno.

Definition at line 223 of file tcp-veno.cc.

◆ GetSsThresh()

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

overridevirtual

Get slow start threshold during Veno multiplicative-decrease phase.

Parameters

tcb	internal congestion state
bytesInFlight	bytes in flight

Returns: the slow start threshold value

Reimplemented from ns3::TcpNewReno.

Definition at line 229 of file tcp-veno.cc.

References ns3::TcpNewReno::GetSsThresh(), m_beta, m_diff, NS_LOG_FUNCTION, and NS_LOG_LOGIC.

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◆ GetTypeId()

TypeId ns3::TcpVeno::GetTypeId ( )

static

Get the type ID.

Returns: the object TypeId

Definition at line 28 of file tcp-veno.cc.

References m_beta, ns3::MakeUintegerAccessor(), ns3::MakeUintegerChecker(), and ns3::TypeId::SetParent().

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◆ IncreaseWindow()

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

overridevirtual

Adjust cwnd following Veno additive increase algorithm.

Parameters

tcb	internal congestion state
segmentsAcked	count of segments ACKed

Reimplemented from ns3::TcpNewReno.

Definition at line 136 of file tcp-veno.cc.

References ns3::TcpNewReno::CongestionAvoidance(), ns3::Time::GetSeconds(), ns3::TcpNewReno::IncreaseWindow(), m_baseRtt, m_beta, m_cntRtt, m_diff, m_doingVenoNow, m_inc, m_minRtt, ns3::Time::Max(), NS_ASSERT, NS_LOG_DEBUG, NS_LOG_FUNCTION, NS_LOG_LOGIC, and ns3::TcpNewReno::SlowStart().

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◆ PktsAcked()

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

overridevirtual

Perform RTT sampling needed to execute Veno algorithm.

The function filters RTT samples from the last RTT to find the current smallest propagation delay + queueing delay (m_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 (m_baseRtt).

Parameters

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

Reimplemented from ns3::TcpCongestionOps.

Definition at line 82 of file tcp-veno.cc.

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

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Member Data Documentation

◆ m_ackCnt

uint32_t ns3::TcpVeno::m_ackCnt

private

Number of received ACK.

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

◆ m_baseRtt

Time ns3::TcpVeno::m_baseRtt

private

Minimum of all RTT measurements seen during connection.

Definition at line 151 of file tcp-veno.h.

Referenced by IncreaseWindow(), and PktsAcked().

◆ m_beta

uint32_t ns3::TcpVeno::m_beta

private

Threshold for congestion detection.

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

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

◆ m_cntRtt

uint32_t ns3::TcpVeno::m_cntRtt

private

Number of RTT measurements during last RTT.

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

Referenced by IncreaseWindow(), and PktsAcked().

◆ m_diff

uint32_t ns3::TcpVeno::m_diff

private

Difference between expected and actual throughput.

Definition at line 155 of file tcp-veno.h.

Referenced by GetSsThresh(), and IncreaseWindow().

◆ m_doingVenoNow

bool ns3::TcpVeno::m_doingVenoNow

private

If true, do Veno for this RTT.

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

Referenced by DisableVeno(), EnableVeno(), and IncreaseWindow().

◆ m_inc

bool ns3::TcpVeno::m_inc

private

If true, cwnd needs to be incremented.

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

Referenced by IncreaseWindow().

◆ m_minRtt

Time ns3::TcpVeno::m_minRtt

private

Minimum of RTTs measured within last RTT.

Definition at line 152 of file tcp-veno.h.

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

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

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

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ TcpVeno() [1/2]

◆ TcpVeno() [2/2]

◆ ~TcpVeno()

Member Function Documentation

◆ CongestionStateSet()

◆ DisableVeno()

◆ EnableVeno()

◆ Fork()

◆ GetName()

◆ GetSsThresh()

◆ GetTypeId()

◆ IncreaseWindow()

◆ PktsAcked()

Member Data Documentation

◆ m_ackCnt

◆ m_baseRtt

◆ m_beta

◆ m_cntRtt

◆ m_diff

◆ m_doingVenoNow

◆ m_inc

◆ m_minRtt