An implementation of TCP HighSpeed. More...

#include "tcp-highspeed.h"

Inheritance diagram for ns3::TcpHighSpeed:

Collaboration diagram for ns3::TcpHighSpeed:

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

	TcpHighSpeed (const TcpHighSpeed &sock)
	Copy constructor.

	~TcpHighSpeed () 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 slow start threshold following HighSpeed principles.

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

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, 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 uint32_t	TableLookupA (uint32_t w)
	Lookup table for the coefficient a (from RFC 3649)

static double	TableLookupB (uint32_t w)
	Lookup table for the coefficient b (from RFC 3649)

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.

Protected Member Functions
void	CongestionAvoidance (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override
	Congestion avoidance of TcpHighSpeed.

Protected Member Functions inherited from ns3::TcpNewReno
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.

Private Attributes
uint32_t	m_ackCnt
	Number of received ACK, corrected with the coefficient a.

Additional Inherited Members
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 HighSpeed.

TCP HighSpeed is designed for high-capacity channels or, in general, for TCP connections with large congestion windows. Conceptually, with respect to the standard TCP, HighSpeed makes the cWnd grow faster during the probing phases and accelerates the cWnd recovery from losses. This behavior is executed only when the window grows beyond a certain threshold, which allows TCP Highspeed to be friendly with standard TCP in environments with heavy congestion, without introducing new dangers of congestion collapse. At the core of TCP HighSpeed there are two functions, a(w) and b(w), which respectively specify the cWnd growth addendum and the cWnd reduction factor when given an actual cWnd value w.

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

Definition at line 38 of file tcp-highspeed.h.

Constructor & Destructor Documentation

◆ TcpHighSpeed() [1/2]

ns3::TcpHighSpeed::TcpHighSpeed ( )

Create an unbound tcp socket.

Definition at line 30 of file tcp-highspeed.cc.

References NS_LOG_FUNCTION.

◆ TcpHighSpeed() [2/2]

ns3::TcpHighSpeed::TcpHighSpeed ( const TcpHighSpeed & sock )

Copy constructor.

Parameters

sock	the object to copy

Definition at line 37 of file tcp-highspeed.cc.

References NS_LOG_FUNCTION.

◆ ~TcpHighSpeed()

ns3::TcpHighSpeed::~TcpHighSpeed ( )

override

Definition at line 44 of file tcp-highspeed.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CongestionAvoidance()

void ns3::TcpHighSpeed::CongestionAvoidance	(	Ptr< TcpSocketState >	tcb,
		uint32_t	segmentsAcked )

overrideprotectedvirtual

Congestion avoidance of TcpHighSpeed.

As implementation choice, we increment cWnd only by MSS, when the right number of ACK has been received. At this point, the important question is: what is the "right number of ACK" ?

As you can recall from RFC, Highspeed works this way:

          w = w + a(w)/w

Let's start when a(w) is 1 (so it is classical NewReno). The formula then is the classical text-book version for NewReno:

          w = w + 1 / w

So, for each segment acked, we increase the window by the quantity 1/w. Or, instead of adding the 1/w quantity for each segment acked, we can track the number of segments acked (m_ackCnt) and increment by 1 MSS when m_ackCnt reaches w.

When a(w) > 1, it means that each segment acked has a different "weight". For instance, when it is equal to 2, we need to increase the window by the quantity 2/w. But, this means that one segment acked is equivalent (from the point of view of incrementing cWnd) to two segments acked in NewReno (1/w + 1/w). That a coefficient is, in other word, the weight of each segment acked. More weight, less ACK are necessary to increment cWnd, which is exactly the Highspeed principle.

Parameters

tcb	internal congestion state
segmentsAcked	count of segments acked

Reimplemented from ns3::TcpNewReno.

Definition at line 88 of file tcp-highspeed.cc.

References m_ackCnt, NS_LOG_FUNCTION, NS_LOG_INFO, and TableLookupA().

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◆ Fork()

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

overridevirtual

Copy the congestion control algorithm across sockets.

Returns: a pointer of the copied object

Implements ns3::TcpCongestionOps.

Definition at line 50 of file tcp-highspeed.cc.

References ns3::Object::CopyObject.

◆ GetName()

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

overridevirtual

Get the name of the congestion control algorithm.

Returns: A string identifying the name

Implements ns3::TcpCongestionOps.

Definition at line 116 of file tcp-highspeed.cc.

◆ GetSsThresh()

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

overridevirtual

Get slow start threshold following HighSpeed principles.

Parameters

tcb	internal congestion state
bytesInFlight	Bytes in flight

Returns: the slow start threshold value

Implements ns3::TcpCongestionOps.

Definition at line 130 of file tcp-highspeed.cc.

References NS_LOG_DEBUG, NS_LOG_FUNCTION, and TableLookupB().

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◆ GetTypeId()

TypeId ns3::TcpHighSpeed::GetTypeId ( )

static

Get the type ID.

Returns: the object TypeId

Definition at line 21 of file tcp-highspeed.cc.

References ns3::TypeId::SetParent().

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◆ TableLookupA()

uint32_t ns3::TcpHighSpeed::TableLookupA ( uint32_t w )

static

Lookup table for the coefficient a (from RFC 3649)

Parameters

w	Window value (in packets)

Returns: the coefficient a

Definition at line 145 of file tcp-highspeed.cc.

Referenced by CongestionAvoidance(), and TcpHighSpeedIncrementTest::DoRun().

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◆ TableLookupB()

double ns3::TcpHighSpeed::TableLookupB ( uint32_t w )

static

Lookup table for the coefficient b (from RFC 3649)

Parameters

w	Window value (in packets)

Returns: the coefficient b

Definition at line 444 of file tcp-highspeed.cc.

Referenced by TcpHighSpeedDecrementTest::DoRun(), and GetSsThresh().

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Member Data Documentation

◆ m_ackCnt

uint32_t ns3::TcpHighSpeed::m_ackCnt

private

Number of received ACK, corrected with the coefficient a.

Definition at line 87 of file tcp-highspeed.h.

Referenced by CongestionAvoidance().

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

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

Public Member Functions

Static Public Member Functions

Protected Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ TcpHighSpeed() [1/2]

◆ TcpHighSpeed() [2/2]

◆ ~TcpHighSpeed()

Member Function Documentation

◆ CongestionAvoidance()

◆ Fork()

◆ GetName()

◆ GetSsThresh()

◆ GetTypeId()

◆ TableLookupA()

◆ TableLookupB()

Member Data Documentation

◆ m_ackCnt