The "Mean--Deviation" RTT estimator, as discussed by Van Jacobson. More...

#include "rtt-estimator.h"

Inheritance diagram for ns3::RttMeanDeviation:

Collaboration diagram for ns3::RttMeanDeviation:

Public Member Functions
	RttMeanDeviation ()

	RttMeanDeviation (const RttMeanDeviation &r)
	Copy constructor.

Ptr< RttEstimator >	Copy () const override
	Copy object (including current internal state)

void	Measurement (Time measure) override
	Add a new measurement to the estimator.

void	Reset () override
	Resets the estimator.

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

	RttEstimator (const RttEstimator &r)
	Copy constructor.

	~RttEstimator () override

Time	GetEstimate () const
	gets the RTT estimate.

uint32_t	GetNSamples () const
	gets the number of samples used in the estimates

Time	GetVariation () const
	Note that this is not a formal statistical variance; it has the the same units as the estimate.

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 final
	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::RttEstimator
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
uint32_t	CheckForReciprocalPowerOfTwo (double val) const
	Utility function to check for possible conversion of a double value (0 < value < 1) to a reciprocal power of two.

void	FloatingPointUpdate (Time m)
	Method to update the rtt and variation estimates using floating point arithmetic, used when the values of Alpha and Beta are not both a reciprocal power of two.

void	IntegerUpdate (Time m, uint32_t rttShift, uint32_t variationShift)
	Method to update the rtt and variation estimates using integer arithmetic, used when the values of Alpha and Beta support the integer conversion.

Private Attributes
double	m_alpha
	Filter gain for average.

double	m_beta
	Filter gain for variation.

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.

Protected Attributes inherited from ns3::RttEstimator
Time	m_estimatedRtt
	Current estimate.

Time	m_estimatedVariation
	Current estimate variation.

uint32_t	m_nSamples
	Number of samples.

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

The "Mean--Deviation" RTT estimator, as discussed by Van Jacobson.

Introspection did not find any typical Config paths.

This class implements the "Mean--Deviation" RTT estimator, as discussed by Van Jacobson and Michael J. Karels, in "Congestion Avoidance and Control", SIGCOMM 88, Appendix A

The default values for the gain (alpha and beta) are set as documented in RFC 6298.

Attributes

Alpha: Gain used in estimating the RTT, must be 0 <= alpha <= 1
- Set with class: ns3::DoubleValue
- Underlying type: double 0:1
- Initial value: 0.125
- Flags: constructwriteread
- Support level: SUPPORTED
Beta: Gain used in estimating the RTT variation, must be 0 <= beta <= 1
- Set with class: ns3::DoubleValue
- Underlying type: double 0:1
- Initial value: 0.25
- Flags: constructwriteread
- Support level: SUPPORTED

Attributes defined in parent class ns3::RttEstimator

InitialEstimation: Initial RTT estimate
- Set with class: ns3::TimeValue
- Underlying type: Time -9.22337e+18ns:+9.22337e+18ns
- Initial value: +1e+09ns
- Flags: constructwriteread
- Support level: SUPPORTED

No TraceSources are defined for this type.
Group: Internet

Size of this type is 104 bytes (on a 64-bit architecture).

Definition at line 110 of file rtt-estimator.h.

Constructor & Destructor Documentation

◆ RttMeanDeviation() [1/2]

ns3::RttMeanDeviation::RttMeanDeviation ( )

Definition at line 133 of file rtt-estimator.cc.

References NS_LOG_FUNCTION.

◆ RttMeanDeviation() [2/2]

ns3::RttMeanDeviation::RttMeanDeviation ( const RttMeanDeviation & r )

Copy constructor.

Parameters

r	the object to copy

Definition at line 138 of file rtt-estimator.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CheckForReciprocalPowerOfTwo()

uint32_t ns3::RttMeanDeviation::CheckForReciprocalPowerOfTwo ( double val ) const

private

Utility function to check for possible conversion of a double value (0 < value < 1) to a reciprocal power of two.

Values of 1/32, 1/16, 1/8, 1/4, and 1/2 (i.e., within the possible range of experimentation for this estimator) are supported.

Parameters

val	value to check

Returns: log base 2 (1/val) if reciprocal power of 2, or zero if not

Definition at line 147 of file rtt-estimator.cc.

References NS_LOG_FUNCTION, and ns3::TOLERANCE.

Referenced by Measurement().

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◆ Copy()

Ptr< RttEstimator > ns3::RttMeanDeviation::Copy ( ) const

overridevirtual

Copy object (including current internal state)

Returns: a copy of itself

Implements ns3::RttEstimator.

Definition at line 246 of file rtt-estimator.cc.

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

◆ FloatingPointUpdate()

void ns3::RttMeanDeviation::FloatingPointUpdate ( Time m )

private

Method to update the rtt and variation estimates using floating point arithmetic, used when the values of Alpha and Beta are not both a reciprocal power of two.

Parameters

m	time measurement

Definition at line 179 of file rtt-estimator.cc.

References ns3::Abs(), ns3::Time::FromDouble(), m_alpha, m_beta, ns3::RttEstimator::m_estimatedRtt, ns3::RttEstimator::m_estimatedVariation, NS_LOG_FUNCTION, ns3::Time::S, and ns3::Time::ToDouble().

Referenced by Measurement().

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◆ GetTypeId()

TypeId ns3::RttMeanDeviation::GetTypeId ( )

static

Get the type ID.

Returns: the object TypeId

Definition at line 113 of file rtt-estimator.cc.

References m_alpha, m_beta, ns3::MakeDoubleAccessor(), ns3::MakeDoubleChecker(), and ns3::TypeId::SetParent().

Referenced by ns3::TcpGeneralTest::CreateSocket(), and ns3::TcpL4Protocol::GetTypeId().

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◆ IntegerUpdate()

void ns3::RttMeanDeviation::IntegerUpdate	(	Time	m,
		uint32_t	rttShift,
		uint32_t	variationShift )

private

Method to update the rtt and variation estimates using integer arithmetic, used when the values of Alpha and Beta support the integer conversion.

Parameters

m	time measurement
rttShift	value corresponding to log base 2 (1/alpha)
variationShift	value corresponding to log base 2 (1/beta)

Definition at line 197 of file rtt-estimator.cc.

References ns3::Time::From(), ns3::Time::GetInteger(), ns3::RttEstimator::m_estimatedRtt, ns3::RttEstimator::m_estimatedVariation, and NS_LOG_FUNCTION.

Referenced by Measurement().

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◆ Measurement()

void ns3::RttMeanDeviation::Measurement ( Time measure )

overridevirtual

Add a new measurement to the estimator.

Parameters

measure the new RTT measure.

Implements ns3::RttEstimator.

Definition at line 216 of file rtt-estimator.cc.

References CheckForReciprocalPowerOfTwo(), FloatingPointUpdate(), IntegerUpdate(), m_alpha, m_beta, ns3::RttEstimator::m_estimatedRtt, ns3::RttEstimator::m_estimatedVariation, ns3::RttEstimator::m_nSamples, NS_LOG_DEBUG, and NS_LOG_FUNCTION.

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◆ Reset()

void ns3::RttMeanDeviation::Reset ( )

overridevirtual

Resets the estimator.

Reimplemented from ns3::RttEstimator.

Definition at line 253 of file rtt-estimator.cc.

References NS_LOG_FUNCTION, and ns3::RttEstimator::Reset().

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Member Data Documentation

◆ m_alpha

double ns3::RttMeanDeviation::m_alpha

private

Filter gain for average.

Definition at line 170 of file rtt-estimator.h.

Referenced by FloatingPointUpdate(), GetTypeId(), and Measurement().

◆ m_beta

double ns3::RttMeanDeviation::m_beta

private

Filter gain for variation.

Definition at line 171 of file rtt-estimator.h.

Referenced by FloatingPointUpdate(), GetTypeId(), and Measurement().

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

src/internet/model/rtt-estimator.h
src/internet/model/rtt-estimator.cc

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Attributes

Attributes defined in parent class ns3::RttEstimator

Constructor & Destructor Documentation

◆ RttMeanDeviation() [1/2]

◆ RttMeanDeviation() [2/2]

Member Function Documentation

◆ CheckForReciprocalPowerOfTwo()

◆ Copy()

◆ FloatingPointUpdate()

◆ GetTypeId()

◆ IntegerUpdate()

◆ Measurement()

◆ Reset()

Member Data Documentation

◆ m_alpha

◆ m_beta