A Discrete-Event Network Simulator
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ns3::TcpCongestionOps Class Referenceabstract

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. More...
 
virtual ~TcpCongestionOps ()
 
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. More...
 
virtual void CongestionStateSet (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCongState_t newState)
 Trigger events/calculations specific to a congestion state. More...
 
virtual void CwndEvent (Ptr< TcpSocketState > tcb, const TcpSocketState::TcpCAEvent_t event)
 Trigger events/calculations on occurrence of congestion window event. More...
 
virtual Ptr< TcpCongestionOpsFork ()=0
 Copy the congestion control algorithm across sockets. More...
 
virtual std::string GetName () const =0
 Get the name of the congestion control algorithm. More...
 
virtual uint32_t GetSsThresh (Ptr< const TcpSocketState > tcb, uint32_t bytesInFlight)=0
 Get the slow start threshold after a loss event. More...
 
virtual bool HasCongControl () const
 Returns true when Congestion Control Algorithm implements CongControl. More...
 
virtual void IncreaseWindow (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
 Congestion avoidance algorithm implementation. More...
 
virtual void PktsAcked (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked, const Time &rtt)
 Timing information on received ACK. More...
 
- Public Member Functions inherited from ns3::Object
 Object ()
 Constructor. More...
 
virtual ~Object ()
 Destructor. More...
 
void AggregateObject (Ptr< Object > other)
 Aggregate two Objects together. More...
 
void Dispose (void)
 Dispose of this Object. More...
 
AggregateIterator GetAggregateIterator (void) const
 Get an iterator to the Objects aggregated to this one. More...
 
virtual TypeId GetInstanceTypeId (void) const
 Get the most derived TypeId for this Object. More...
 
template<typename T >
Ptr< T > GetObject (void) const
 Get a pointer to the requested aggregated Object. More...
 
template<typename T >
Ptr< T > GetObject (TypeId tid) const
 Get a pointer to the requested aggregated Object by TypeId. More...
 
void Initialize (void)
 Invoke DoInitialize on all Objects aggregated to this one. More...
 
bool IsInitialized (void) const
 Check if the object has been initialized. More...
 
- Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
 SimpleRefCount ()
 Default constructor. More...
 
 SimpleRefCount (const SimpleRefCount &o)
 Copy constructor. More...
 
uint32_t GetReferenceCount (void) const
 Get the reference count of the object. More...
 
SimpleRefCountoperator= (const SimpleRefCount &o)
 Assignment operator. More...
 
void Ref (void) const
 Increment the reference count. More...
 
void Unref (void) const
 Decrement the reference count. More...
 
- Public Member Functions inherited from ns3::ObjectBase
virtual ~ObjectBase ()
 Virtual destructor. More...
 
void GetAttribute (std::string name, AttributeValue &value) const
 Get the value of an attribute, raising fatal errors if unsuccessful. More...
 
bool GetAttributeFailSafe (std::string name, AttributeValue &value) const
 Get the value of an attribute without raising erros. More...
 
void SetAttribute (std::string name, const AttributeValue &value)
 Set a single attribute, raising fatal errors if unsuccessful. More...
 
bool SetAttributeFailSafe (std::string name, const AttributeValue &value)
 Set a single attribute without raising errors. More...
 
bool TraceConnect (std::string name, std::string context, const CallbackBase &cb)
 Connect a TraceSource to a Callback with a context. More...
 
bool TraceConnectWithoutContext (std::string name, const CallbackBase &cb)
 Connect a TraceSource to a Callback without a context. More...
 
bool TraceDisconnect (std::string name, std::string context, const CallbackBase &cb)
 Disconnect from a TraceSource a Callback previously connected with a context. More...
 
bool TraceDisconnectWithoutContext (std::string name, const CallbackBase &cb)
 Disconnect from a TraceSource a Callback previously connected without a context. More...
 

Static Public Member Functions

static TypeId GetTypeId (void)
 Get the type ID. More...
 
- Static Public Member Functions inherited from ns3::Object
static TypeId GetTypeId (void)
 Register this type. More...
 
- Static Public Member Functions inherited from ns3::ObjectBase
static TypeId GetTypeId (void)
 Get the type ID. More...
 

Additional Inherited Members

- Protected Member Functions inherited from ns3::Object
 Object (const Object &o)
 Copy an Object. More...
 
virtual void DoDispose (void)
 Destructor implementation. More...
 
virtual void DoInitialize (void)
 Initialize() implementation. More...
 
virtual void NotifyNewAggregate (void)
 Notify all Objects aggregated to this one of a new Object being aggregated. More...
 
- Protected Member Functions inherited from ns3::ObjectBase
void ConstructSelf (const AttributeConstructionList &attributes)
 Complete construction of ObjectBase; invoked by derived classes. More...
 
virtual void NotifyConstructionCompleted (void)
 Notifier called once the ObjectBase is fully constructed. More...
 

Detailed Description

Congestion control abstract class.


Introspection did not find any typical Config paths.

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


No Attributes are defined for this type.
No TraceSources are defined for this type.
Size of this type is 32 bytes (on a 64-bit architecture).

Definition at line 51 of file tcp-congestion-ops.h.

Constructor & Destructor Documentation

◆ TcpCongestionOps() [1/2]

ns3::TcpCongestionOps::TcpCongestionOps ( )

Definition at line 39 of file tcp-congestion-ops.cc.

◆ TcpCongestionOps() [2/2]

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

Copy constructor.

Parameters
otherobject to copy.

Definition at line 43 of file tcp-congestion-ops.cc.

◆ ~TcpCongestionOps()

ns3::TcpCongestionOps::~TcpCongestionOps ( )
virtual

Definition at line 47 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
tcbinternal congestion state
rcRate information for the connection
rsRate sample (over a period of time) information

Definition at line 85 of file tcp-congestion-ops.cc.

References NS_LOG_FUNCTION, and NS_UNUSED.

◆ 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;
Parameters
tcbinternal congestion state
newStatenew congestion state to which the TCP is going to switch

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

Definition at line 65 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
tcbinternal congestion state
eventthe event which triggered this function

Definition at line 72 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::TcpNewReno, ns3::TcpYeah, ns3::TcpIllinois, ns3::TcpVeno, ns3::TcpVegas, ns3::TcpWestwood, ns3::TcpBic, ns3::TcpLedbat, ns3::TcpScalable, ns3::TcpHighSpeed, ns3::TcpLp, ns3::TcpHybla, and ns3::TcpHtcp.

◆ 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::TcpNewReno, ns3::TcpIllinois, ns3::TcpBic, ns3::TcpYeah, ns3::TcpVeno, ns3::TcpLedbat, ns3::TcpVegas, ns3::TcpScalable, ns3::TcpLp, ns3::TcpHybla, ns3::TcpHighSpeed, and ns3::TcpHtcp.

◆ 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 implementator 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
tcbinternal congestion state
bytesInFlighttotal bytes in flight
Returns
Slow start threshold

Implemented in ns3::TcpNewReno, ns3::TcpYeah, ns3::TcpIllinois, ns3::TcpVeno, ns3::TcpVegas, ns3::TcpBic, ns3::TcpWestwood, ns3::TcpScalable, ns3::TcpHighSpeed, and ns3::TcpHtcp.

◆ GetTypeId()

TypeId ns3::TcpCongestionOps::GetTypeId ( void  )
static

Get the type ID.

Returns
the object TypeId

Definition at line 30 of file tcp-congestion-ops.cc.

References ns3::TypeId::SetParent().

+ Here is the call graph for this function:

◆ 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.

Definition at line 79 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
tcbinternal congestion state
segmentsAckedcount of segments acked

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

Definition at line 52 of file tcp-congestion-ops.cc.

References NS_LOG_FUNCTION.

◆ 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
tcbinternal congestion state
segmentsAckedcount of segments acked
rttlast rtt

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

Definition at line 58 of file tcp-congestion-ops.cc.

References NS_LOG_FUNCTION.


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