An implementation of DCTCP. More...

#include "tcp-dctcp.h"

Inheritance diagram for ns3::TcpDctcp:

Collaboration diagram for ns3::TcpDctcp:

Public Types
typedef void(*	CongestionEstimateTracedCallback) (uint32_t bytesAcked, uint32_t bytesMarked, double alpha)
	TracedCallback signature for DCTCP update of congestion state.

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

	TcpDctcp (const TcpDctcp &sock)
	Copy constructor.

	~TcpDctcp () override
	Destructor.

void	CwndEvent (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCAEvent_t event) override
	Trigger events/calculations on occurrence of congestion window event.

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	Init (Ptr< TcpSocketState > tcb) override
	Set configuration required by congestion control algorithm, This method will force DctcpEcn mode and will force usage of either ECT(0) or ECT(1) (depending on the 'UseEct0' attribute), despite any other configuration in the base classes.

void	PktsAcked (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked, const Time &rtt) override
	Timing information on received ACK.

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

	TcpLinuxReno (const TcpLinuxReno &sock)
	Copy constructor.

	~TcpLinuxReno () 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
	Congestion avoidance algorithm implementation.

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 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) 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.

virtual TypeId	GetInstanceTypeId () const =0
	Get the most derived TypeId for this Object.

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::TcpLinuxReno
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	CeState0to1 (Ptr< TcpSocketState > tcb)
	Changes state of m_ceState to true.

void	CeState1to0 (Ptr< TcpSocketState > tcb)
	Changes state of m_ceState to false.

void	InitializeDctcpAlpha (double alpha)
	Initialize the value of m_alpha.

void	Reset (Ptr< TcpSocketState > tcb)
	Resets the value of m_ackedBytesEcn, m_ackedBytesTotal and m_nextSeq.

void	UpdateAckReserved (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCAEvent_t event)
	Updates the value of m_delayedAckReserved.

Private Attributes
uint32_t	m_ackedBytesEcn
	Number of acked bytes which are marked.

uint32_t	m_ackedBytesTotal
	Total number of acked bytes.

double	m_alpha
	Parameter used to estimate the amount of network congestion.

bool	m_ceState
	DCTCP Congestion Experienced state.

bool	m_delayedAckReserved
	Delayed Ack state.

double	m_g
	Estimation gain.

bool	m_initialized
	Whether DCTCP has been initialized.

SequenceNumber32	m_nextSeq
	TCP sequence number threshold for beginning a new observation window.

bool	m_nextSeqFlag
	Variable used in setting the value of m_nextSeq for first time.

SequenceNumber32	m_priorRcvNxt
	Sequence number of the first missing byte in data.

bool	m_priorRcvNxtFlag
	Variable used in setting the value of m_priorRcvNxt for first time.

TracedCallback< uint32_t, uint32_t, double >	m_traceCongestionEstimate
	Callback pointer for congestion state update.

bool	m_useEct0
	Use ECT(0) for ECN codepoint.

Additional Inherited Members
Protected Member Functions inherited from ns3::TcpLinuxReno
virtual void	CongestionAvoidance (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
	Congestion avoidance phase handler.

virtual uint32_t	SlowStart (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
	Slow start phase handler.

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 Functions 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 DCTCP.

This model implements all of the endpoint capabilities mentioned in the DCTCP SIGCOMM paper. Note that this model presently will not do any fallback to RFC 5681 congestion avoidance as specified in RFC 8257 Section 3.5, so it should only be used in a simulation that does not involve packet loss.

Config Paths

ns3::TcpDctcp is accessible through the following paths with Config::Set and Config::Connect:

"/NodeList/[i]/$ns3::TcpL4Protocol/SocketList/[i]/CongestionOps/$ns3::TcpDctcp"
"/NodeList/[i]/$ns3::TcpL4Protocol/SocketList/[i]/CongestionOps/$ns3::TcpLinuxReno/$ns3::TcpDctcp"

Attributes

DctcpAlphaOnInit: Initial alpha value
- Set with class: ns3::DoubleValue
- Underlying type: double 0:1
- Initial value: 1
- Flags: constructwrite
DctcpShiftG: Parameter G for updating dctcp_alpha
- Set with class: ns3::DoubleValue
- Underlying type: double 0:1
- Initial value: 0.0625
- Flags: constructwriteread
UseEct0: Use ECT(0) for ECN codepoint, if false use ECT(1)
- Set with class: ns3::BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: constructwriteread

TraceSources

CongestionEstimate: Update sender-side congestion estimate state
Callback signature: ns3::TcpDctcp::CongestionEstimateTracedCallback

Size of this type is 120 bytes (on a 64-bit architecture).

Definition at line 42 of file tcp-dctcp.h.

Member Typedef Documentation

◆ CongestionEstimateTracedCallback

typedef void(* ns3::TcpDctcp::CongestionEstimateTracedCallback) (uint32_t bytesAcked, uint32_t bytesMarked, double alpha)

TracedCallback signature for DCTCP update of congestion state.

Parameters

[in]	bytesAcked	Bytes acked in this observation window
[in]	bytesMarked	Bytes marked in this observation window
[in]	alpha	New alpha (congestion estimate) value

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

Constructor & Destructor Documentation

◆ TcpDctcp() [1/2]

ns3::TcpDctcp::TcpDctcp ( )

Create an unbound tcp socket.

Definition at line 71 of file tcp-dctcp.cc.

References NS_LOG_FUNCTION.

◆ TcpDctcp() [2/2]

ns3::TcpDctcp::TcpDctcp ( const TcpDctcp & sock )

Copy constructor.

Parameters

sock	the object to copy

Definition at line 86 of file tcp-dctcp.cc.

References NS_LOG_FUNCTION.

◆ ~TcpDctcp()

ns3::TcpDctcp::~TcpDctcp ( )

override

Destructor.

Definition at line 104 of file tcp-dctcp.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CeState0to1()

void ns3::TcpDctcp::CeState0to1 ( Ptr< TcpSocketState > tcb )

private

Changes state of m_ceState to true.

Parameters

tcb	internal congestion state

Definition at line 183 of file tcp-dctcp.cc.

References ns3::TcpHeader::ACK, ns3::TcpSocketState::ECN_CE_RCVD, m_ceState, m_delayedAckReserved, m_priorRcvNxt, m_priorRcvNxtFlag, and NS_LOG_FUNCTION.

Referenced by CwndEvent().

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◆ CeState1to0()

void ns3::TcpDctcp::CeState1to0 ( Ptr< TcpSocketState > tcb )

private

Changes state of m_ceState to false.

Parameters

tcb	internal congestion state

Definition at line 210 of file tcp-dctcp.cc.

References ns3::TcpHeader::ACK, ns3::TcpHeader::ECE, ns3::TcpSocketState::ECN_CE_RCVD, ns3::TcpSocketState::ECN_IDLE, ns3::TcpSocketState::ECN_SENDING_ECE, m_ceState, m_delayedAckReserved, m_priorRcvNxt, m_priorRcvNxtFlag, and NS_LOG_FUNCTION.

Referenced by CwndEvent().

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◆ CwndEvent()

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

overridevirtual

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 from ns3::TcpCongestionOps.

Definition at line 266 of file tcp-dctcp.cc.

References ns3::TcpSocketState::CA_EVENT_DELAYED_ACK, ns3::TcpSocketState::CA_EVENT_ECN_IS_CE, ns3::TcpSocketState::CA_EVENT_ECN_NO_CE, ns3::TcpSocketState::CA_EVENT_NON_DELAYED_ACK, CeState0to1(), CeState1to0(), NS_LOG_FUNCTION, and UpdateAckReserved().

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◆ Fork()

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

overridevirtual

Copy the congestion control algorithm across sockets.

Returns: a pointer of the copied object

Implements ns3::TcpCongestionOps.

Definition at line 110 of file tcp-dctcp.cc.

References NS_LOG_FUNCTION.

◆ GetName()

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

overridevirtual

Get the name of the congestion control algorithm.

Returns: A string identifying the name

Implements ns3::TcpCongestionOps.

Definition at line 66 of file tcp-dctcp.cc.

◆ GetSsThresh()

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

overridevirtual

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

Implements ns3::TcpCongestionOps.

Definition at line 131 of file tcp-dctcp.cc.

References m_alpha, and NS_LOG_FUNCTION.

◆ GetTypeId()

TypeId ns3::TcpDctcp::GetTypeId ( )

static

Get the type ID.

Returns: the object TypeId

Definition at line 36 of file tcp-dctcp.cc.

References InitializeDctcpAlpha(), m_g, m_traceCongestionEstimate, m_useEct0, ns3::MakeBooleanAccessor(), ns3::MakeBooleanChecker(), ns3::MakeDoubleAccessor(), ns3::MakeTraceSourceAccessor(), and ns3::TypeId::SetParent().

Referenced by TcpDctcpCodePointsTest::CreateReceiverSocket(), and TcpDctcpCodePointsTest::CreateSenderSocket().

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◆ Init()

void ns3::TcpDctcp::Init ( Ptr< TcpSocketState > tcb )

overridevirtual

Set configuration required by congestion control algorithm, This method will force DctcpEcn mode and will force usage of either ECT(0) or ECT(1) (depending on the 'UseEct0' attribute), despite any other configuration in the base classes.

Parameters

tcb	internal congestion state

Reimplemented from ns3::TcpCongestionOps.

Definition at line 117 of file tcp-dctcp.cc.

References ns3::TcpSocketState::DctcpEcn, ns3::TcpSocketState::Ect0, ns3::TcpSocketState::Ect1, m_initialized, m_useEct0, NS_LOG_FUNCTION, NS_LOG_INFO, and ns3::TcpSocketState::On.

◆ InitializeDctcpAlpha()

void ns3::TcpDctcp::InitializeDctcpAlpha ( double alpha )

private

Initialize the value of m_alpha.

Parameters

alpha DCTCP alpha parameter

Definition at line 166 of file tcp-dctcp.cc.

References m_alpha, m_initialized, NS_ABORT_MSG_IF, and NS_LOG_FUNCTION.

Referenced by GetTypeId().

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◆ PktsAcked()

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

overridevirtual

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 from ns3::TcpCongestionOps.

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

References ns3::TcpSocketState::ECN_ECE_RCVD, m_ackedBytesEcn, m_ackedBytesTotal, m_alpha, m_g, m_nextSeq, m_nextSeqFlag, m_traceCongestionEstimate, NS_LOG_FUNCTION, NS_LOG_INFO, and Reset().

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◆ Reset()

void ns3::TcpDctcp::Reset ( Ptr< TcpSocketState > tcb )

private

Resets the value of m_ackedBytesEcn, m_ackedBytesTotal and m_nextSeq.

Parameters

tcb	internal congestion state

Definition at line 174 of file tcp-dctcp.cc.

References m_ackedBytesEcn, m_ackedBytesTotal, m_nextSeq, and NS_LOG_FUNCTION.

Referenced by PktsAcked().

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◆ UpdateAckReserved()

void ns3::TcpDctcp::UpdateAckReserved	(	Ptr< TcpSocketState >	tcb,
		const TcpSocketState::TcpCAEvent_t	event
	)

private

Updates the value of m_delayedAckReserved.

Parameters

tcb	internal congestion state
event	the congestion window event

Definition at line 242 of file tcp-dctcp.cc.

References ns3::TcpSocketState::CA_EVENT_DELAYED_ACK, ns3::TcpSocketState::CA_EVENT_NON_DELAYED_ACK, m_delayedAckReserved, and NS_LOG_FUNCTION.

Referenced by CwndEvent().

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Member Data Documentation

◆ m_ackedBytesEcn

uint32_t ns3::TcpDctcp::m_ackedBytesEcn

private

Number of acked bytes which are marked.

Definition at line 134 of file tcp-dctcp.h.

Referenced by PktsAcked(), and Reset().

◆ m_ackedBytesTotal

uint32_t ns3::TcpDctcp::m_ackedBytesTotal

private

Total number of acked bytes.

Definition at line 135 of file tcp-dctcp.h.

Referenced by PktsAcked(), and Reset().

◆ m_alpha

double ns3::TcpDctcp::m_alpha

private

Parameter used to estimate the amount of network congestion.

Definition at line 138 of file tcp-dctcp.h.

Referenced by GetSsThresh(), InitializeDctcpAlpha(), and PktsAcked().

◆ m_ceState

bool ns3::TcpDctcp::m_ceState

private

DCTCP Congestion Experienced state.

Definition at line 142 of file tcp-dctcp.h.

Referenced by CeState0to1(), and CeState1to0().

◆ m_delayedAckReserved

bool ns3::TcpDctcp::m_delayedAckReserved

private

Delayed Ack state.

Definition at line 143 of file tcp-dctcp.h.

Referenced by CeState0to1(), CeState1to0(), and UpdateAckReserved().

◆ m_g

double ns3::TcpDctcp::m_g

private

Estimation gain.

Definition at line 144 of file tcp-dctcp.h.

Referenced by GetTypeId(), and PktsAcked().

◆ m_initialized

bool ns3::TcpDctcp::m_initialized

private

Whether DCTCP has been initialized.

Definition at line 146 of file tcp-dctcp.h.

Referenced by Init(), and InitializeDctcpAlpha().

◆ m_nextSeq

SequenceNumber32 ns3::TcpDctcp::m_nextSeq

private

TCP sequence number threshold for beginning a new observation window.

Definition at line 140 of file tcp-dctcp.h.

Referenced by PktsAcked(), and Reset().

◆ m_nextSeqFlag

bool ns3::TcpDctcp::m_nextSeqFlag

private

Variable used in setting the value of m_nextSeq for first time.

Definition at line 141 of file tcp-dctcp.h.

Referenced by PktsAcked().

◆ m_priorRcvNxt

SequenceNumber32 ns3::TcpDctcp::m_priorRcvNxt

private

Sequence number of the first missing byte in data.

Definition at line 136 of file tcp-dctcp.h.

Referenced by CeState0to1(), and CeState1to0().

◆ m_priorRcvNxtFlag

bool ns3::TcpDctcp::m_priorRcvNxtFlag

private

Variable used in setting the value of m_priorRcvNxt for first time.

Definition at line 137 of file tcp-dctcp.h.

Referenced by CeState0to1(), and CeState1to0().

◆ m_traceCongestionEstimate

TracedCallback<uint32_t, uint32_t, double> ns3::TcpDctcp::m_traceCongestionEstimate

private

Callback pointer for congestion state update.

Definition at line 150 of file tcp-dctcp.h.

Referenced by GetTypeId(), and PktsAcked().

◆ m_useEct0

bool ns3::TcpDctcp::m_useEct0

private

Use ECT(0) for ECN codepoint.

Definition at line 145 of file tcp-dctcp.h.

Referenced by GetTypeId(), and Init().

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

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

Public Types

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Config Paths

Attributes

TraceSources

Member Typedef Documentation

◆ CongestionEstimateTracedCallback

Constructor & Destructor Documentation

◆ TcpDctcp() [1/2]

◆ TcpDctcp() [2/2]

◆ ~TcpDctcp()

Member Function Documentation

◆ CeState0to1()

◆ CeState1to0()

◆ CwndEvent()

◆ Fork()

◆ GetName()

◆ GetSsThresh()

◆ GetTypeId()

◆ Init()

◆ InitializeDctcpAlpha()

◆ PktsAcked()

◆ Reset()

◆ UpdateAckReserved()

Member Data Documentation

◆ m_ackedBytesEcn

◆ m_ackedBytesTotal

◆ m_alpha

◆ m_ceState

◆ m_delayedAckReserved

◆ m_g

◆ m_initialized

◆ m_nextSeq

◆ m_nextSeqFlag

◆ m_priorRcvNxt

◆ m_priorRcvNxtFlag

◆ m_traceCongestionEstimate

◆ m_useEct0