Congestion control abstract class. More...

#include "tcp-congestion-ops.h"

Inheritance diagram for ns3::TcpCongestionOps:

Collaboration diagram for ns3::TcpCongestionOps:

Public Member Functions
	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 Ptr< TcpCongestionOps >	Fork ()=0
	Copy the congestion control algorithm across sockets.

virtual std::string	GetName () const =0
	Get the name of the congestion control algorithm.

virtual uint32_t	GetSsThresh (Ptr< const TcpSocketState > tcb, uint32_t bytesInFlight)=0
	Get the slow start threshold after a loss event.

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

virtual void	IncreaseWindow (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
	Congestion avoidance algorithm implementation.

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 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.

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.

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

Congestion control abstract class.

The design is inspired by what Linux v4.0 does (but it has been in place for years). The congestion control is split from the main socket code, and it is a pluggable component. An interface has been defined; variables are maintained in the TcpSocketState class, while subclasses of TcpCongestionOps operate over an instance of that class.

Only three methods have been implemented right now; however, Linux has many others, which can be added later in ns-3.

See also: IncreaseWindow; PktsAcked

Definition at line 40 of file tcp-congestion-ops.h.

Constructor & Destructor Documentation

◆ TcpCongestionOps() [1/2]

ns3::TcpCongestionOps::TcpCongestionOps ( )

Definition at line 26 of file tcp-congestion-ops.cc.

◆ TcpCongestionOps() [2/2]

ns3::TcpCongestionOps::TcpCongestionOps ( const TcpCongestionOps & other )

Copy constructor.

Parameters

other object to copy.

Definition at line 31 of file tcp-congestion-ops.cc.

◆ ~TcpCongestionOps()

ns3::TcpCongestionOps::~TcpCongestionOps ( )

override

Definition at line 36 of file tcp-congestion-ops.cc.

Member Function Documentation

◆ CongControl()

void ns3::TcpCongestionOps::CongControl	(	Ptr< TcpSocketState >	tcb,
		const TcpRateOps::TcpRateConnection &	rc,
		const TcpRateOps::TcpRateSample &	rs )

virtual

Called when packets are delivered to update cwnd and pacing rate.

This function mimics the function cong_control in Linux. It is allowed to change directly cWnd and pacing rate.

Parameters

tcb	internal congestion state
rc	Rate information for the connection
rs	Rate sample (over a period of time) information

Reimplemented in ns3::TcpBbr.

Definition at line 72 of file tcp-congestion-ops.cc.

References NS_LOG_FUNCTION.

◆ CongestionStateSet()

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

virtual

Trigger events/calculations specific to a congestion state.

This function mimics the notification function set_state in Linux. The function does not change the congestion state in the tcb; it notifies the congestion control algorithm that this state is about to be changed. The tcb->m_congState variable must be separately set; for example:

m_congestionControl->CongestionStateSet (m_tcb, TcpSocketState::CA_RECOVERY);

m_tcb->m_congState = TcpSocketState::CA_RECOVERY;

ns3::TcpSocketState::CA_RECOVERY

@ CA_RECOVERY

CWND was reduced, we are fast-retransmitting.

Definition tcp-socket-state.h:77

Parameters

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

Reimplemented in ns3::TcpBbr, ns3::TcpCubic, ns3::TcpIllinois, ns3::TcpVegas, ns3::TcpVeno, and ns3::TcpYeah.

Definition at line 53 of file tcp-congestion-ops.cc.

References NS_LOG_FUNCTION.

◆ CwndEvent()

void ns3::TcpCongestionOps::CwndEvent	(	Ptr< TcpSocketState >	tcb,
		const TcpSocketState::TcpCAEvent_t	event )

virtual

Trigger events/calculations on occurrence of congestion window event.

This function mimics the function cwnd_event in Linux. The function is called in case of congestion window events.

Parameters

tcb	internal congestion state
event	the event which triggered this function

Reimplemented in ns3::TcpBbr, and ns3::TcpDctcp.

Definition at line 60 of file tcp-congestion-ops.cc.

References NS_LOG_FUNCTION.

◆ Fork()

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

pure virtual

Copy the congestion control algorithm across sockets.

Returns: a pointer of the copied object

Implemented in ns3::TcpBbr, ns3::TcpBic, ns3::TcpCubic, ns3::TcpDctcp, ns3::TcpHighSpeed, ns3::TcpHtcp, ns3::TcpHybla, ns3::TcpIllinois, ns3::TcpLedbat, ns3::TcpLinuxReno, ns3::TcpLp, ns3::TcpNewReno, ns3::TcpScalable, ns3::TcpVegas, ns3::TcpVeno, ns3::TcpWestwoodPlus, and ns3::TcpYeah.

◆ GetName()

virtual std::string ns3::TcpCongestionOps::GetName ( ) const

pure virtual

Get the name of the congestion control algorithm.

Returns: A string identifying the name

Implemented in ns3::TcpBbr, ns3::TcpBic, ns3::TcpCubic, ns3::TcpDctcp, ns3::TcpHighSpeed, ns3::TcpHtcp, ns3::TcpHybla, ns3::TcpIllinois, ns3::TcpLedbat, ns3::TcpLinuxReno, ns3::TcpLp, ns3::TcpNewReno, ns3::TcpScalable, ns3::TcpVegas, ns3::TcpVeno, and ns3::TcpYeah.

◆ GetSsThresh()

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

pure virtual

Get the slow start threshold after a loss event.

Is guaranteed that the congestion control state (TcpAckState_t) is changed BEFORE the invocation of this method. The implementer should return the slow start threshold (and not change it directly) because, in the future, the TCP implementation may require to instantly recover from a loss event (e.g. when there is a network with an high reordering factor).

Parameters

tcb	internal congestion state
bytesInFlight	total bytes in flight

Returns: Slow start threshold

Implemented in ns3::TcpBbr, ns3::TcpBic, ns3::TcpCubic, ns3::TcpDctcp, ns3::TcpHighSpeed, ns3::TcpHtcp, ns3::TcpIllinois, ns3::TcpLinuxReno, ns3::TcpNewReno, ns3::TcpScalable, ns3::TcpVegas, ns3::TcpVeno, ns3::TcpWestwoodPlus, and ns3::TcpYeah.

◆ GetTypeId()

TypeId ns3::TcpCongestionOps::GetTypeId ( )

static

Get the type ID.

Returns: the object TypeId

Definition at line 19 of file tcp-congestion-ops.cc.

References ns3::TypeId::SetParent().

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◆ HasCongControl()

bool ns3::TcpCongestionOps::HasCongControl ( ) const

virtual

Returns true when Congestion Control Algorithm implements CongControl.

Returns: true if CC implements CongControl function

This function is the equivalent in C++ of the C checks that are used in the Linux kernel to see if an optional function has been defined. Since CongControl is optional, not all congestion controls have it. But, from the perspective of TcpSocketBase, the behavior is different if CongControl is present. Therefore, this check should return true for any congestion controls that implements the CongControl optional function.

Reimplemented in MimicCongControl, and ns3::TcpBbr.

Definition at line 66 of file tcp-congestion-ops.cc.

◆ IncreaseWindow()

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

virtual

Congestion avoidance algorithm implementation.

Mimic the function cong_avoid in Linux. New segments have been ACKed, and the congestion control duty is to update the window.

The function is allowed to change directly cWnd and/or ssThresh.

Parameters

tcb	internal congestion state
segmentsAcked	count of segments acked

Reimplemented in ns3::TcpBic, ns3::TcpCubic, ns3::TcpIllinois, ns3::TcpLedbat, ns3::TcpLinuxReno, ns3::TcpNewReno, ns3::TcpVegas, ns3::TcpVeno, and ns3::TcpYeah.

Definition at line 41 of file tcp-congestion-ops.cc.

References NS_LOG_FUNCTION.

◆ Init()

virtual void ns3::TcpCongestionOps::Init ( Ptr< TcpSocketState > tcb )

inlinevirtual

Set configuration required by congestion control algorithm.

Parameters

tcb	internal congestion state

Reimplemented in ns3::TcpCubic, and ns3::TcpDctcp.

Definition at line 71 of file tcp-congestion-ops.h.

◆ PktsAcked()

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

virtual

Timing information on received ACK.

The function is called every time an ACK is received (only one time also for cumulative ACKs) and contains timing information. It is optional (congestion controls need not implement it) and the default implementation does nothing.

Parameters

tcb	internal congestion state
segmentsAcked	count of segments acked
rtt	last rtt

Reimplemented in DummyCongControl, ns3::TcpCubic, ns3::TcpDctcp, ns3::TcpHtcp, ns3::TcpHybla, ns3::TcpIllinois, ns3::TcpLedbat, ns3::TcpLp, ns3::TcpVegas, ns3::TcpVeno, ns3::TcpWestwoodPlus, and ns3::TcpYeah.

Definition at line 47 of file tcp-congestion-ops.cc.

References NS_LOG_FUNCTION.

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

src/internet/model/tcp-congestion-ops.h
src/internet/model/tcp-congestion-ops.cc

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ TcpCongestionOps() [1/2]

◆ TcpCongestionOps() [2/2]

◆ ~TcpCongestionOps()

Member Function Documentation

◆ CongControl()

◆ CongestionStateSet()

◆ CwndEvent()

◆ Fork()

◆ GetName()

◆ GetSsThresh()

◆ GetTypeId()

◆ HasCongControl()

◆ IncreaseWindow()

◆ Init()

◆ PktsAcked()