A Discrete-Event Network Simulator
API
ns3::TcpHybla Class Reference

Implementation of the TCP Hybla algorithm. More...

#include "tcp-hybla.h"

+ Inheritance diagram for ns3::TcpHybla:
+ Collaboration diagram for ns3::TcpHybla:

Public Member Functions

 TcpHybla (void)
 Create an unbound tcp socket. More...
 
 TcpHybla (const TcpHybla &sock)
 Copy constructor. More...
 
virtual ~TcpHybla (void) override
 
virtual Ptr< TcpCongestionOpsFork () override
 Copy the congestion control algorithm across sockets. More...
 
virtual std::string GetName () const override
 Get the name of the congestion control algorithm. More...
 
virtual void PktsAcked (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked, const Time &rtt) override
 Timing information on received ACK. More...
 
- Public Member Functions inherited from ns3::TcpNewReno
 TcpNewReno ()
 
 TcpNewReno (const TcpNewReno &sock)
 Copy constructor. More...
 
 ~TcpNewReno ()
 
virtual uint32_t GetSsThresh (Ptr< const TcpSocketState > tcb, uint32_t bytesInFlight)
 Get the slow start threshold after a loss event. More...
 
virtual void IncreaseWindow (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
 Try to increase the cWnd following the NewReno specification. More...
 
- Public Member Functions inherited from ns3::TcpCongestionOps
 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 bool HasCongControl () const
 Returns true when Congestion Control Algorithm implements CongControl. 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::TcpNewReno
static TypeId GetTypeId (void)
 Get the type ID. More...
 
- Static Public Member Functions inherited from ns3::TcpCongestionOps
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...
 

Protected Member Functions

virtual void CongestionAvoidance (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override
 NewReno congestion avoidance. More...
 
virtual uint32_t SlowStart (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override
 
Tcp NewReno slow start algorithm More...
 
- 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...
 

Private Member Functions

void RecalcParam (const Ptr< TcpSocketState > &tcb)
 Recalculate algorithm parameters. More...
 

Private Attributes

double m_cWndCnt
 cWnd integer-to-float counter More...
 
TracedValue< double > m_rho
 Rho parameter. More...
 
Time m_rRtt
 Reference RTT. More...
 

Additional Inherited Members

Detailed Description

Implementation of the TCP Hybla algorithm.


Introspection did not find any typical Config paths.

The key idea behind TCP Hybla is to obtain for long RTT connections the same instantaneous transmission rate of a reference TCP connection with lower RTT. With analytical steps, it is shown that this goal can be achieved by modifying the time scale, in order for the throughput to be independent from the RTT. This independence is obtained through the use of a coefficient rho.

This coefficient is used to calculate both the slow start threshold and the congestion window when in slow start and in congestion avoidance, respectively.

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


Attributes

  • RRTT: Reference RTT
    • Set with class: ns3::TimeValue
    • Underlying type: Time –9223372036854775808.0ns:+9223372036854775807.0ns
    • Initial value: +50000000.0ns
    • Flags: construct write read

TraceSources

Size of this type is 72 bytes (on a 64-bit architecture).

Definition at line 45 of file tcp-hybla.h.

Constructor & Destructor Documentation

◆ TcpHybla() [1/2]

ns3::TcpHybla::TcpHybla ( void  )

Create an unbound tcp socket.

Definition at line 48 of file tcp-hybla.cc.

References NS_LOG_FUNCTION.

◆ TcpHybla() [2/2]

ns3::TcpHybla::TcpHybla ( const TcpHybla sock)

Copy constructor.

Parameters
sockthe object to copy

Definition at line 56 of file tcp-hybla.cc.

References NS_LOG_FUNCTION.

◆ ~TcpHybla()

ns3::TcpHybla::~TcpHybla ( void  )
overridevirtual

Definition at line 64 of file tcp-hybla.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CongestionAvoidance()

void ns3::TcpHybla::CongestionAvoidance ( Ptr< TcpSocketState tcb,
uint32_t  segmentsAcked 
)
overrideprotectedvirtual

NewReno congestion avoidance.

During congestion avoidance, cwnd is incremented by roughly 1 full-sized segment per round-trip time (RTT).

Parameters
tcbinternal congestion state
segmentsAckedcount of segments acked

Reimplemented from ns3::TcpNewReno.

Definition at line 124 of file tcp-hybla.cc.

References ns3::TcpSocketState::GetCwndInSegments(), ns3::TcpSocketState::m_cWnd, m_cWndCnt, m_rho, ns3::TcpSocketState::m_segmentSize, ns3::TcpSocketState::m_ssThresh, NS_ASSERT, NS_LOG_FUNCTION, and NS_LOG_INFO.

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◆ Fork()

Ptr< TcpCongestionOps > ns3::TcpHybla::Fork ( )
overridevirtual

Copy the congestion control algorithm across sockets.

Returns
a pointer of the copied object

Reimplemented from ns3::TcpNewReno.

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

◆ GetName()

std::string ns3::TcpHybla::GetName ( ) const
overridevirtual

Get the name of the congestion control algorithm.

Returns
A string identifying the name

Reimplemented from ns3::TcpNewReno.

Definition at line 172 of file tcp-hybla.cc.

◆ GetTypeId()

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

Get the type ID.

Returns
the object TypeId

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

References m_rho, m_rRtt, ns3::MakeTimeAccessor(), ns3::MakeTimeChecker(), ns3::MakeTraceSourceAccessor(), ns3::MilliSeconds(), and ns3::TypeId::SetParent().

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◆ PktsAcked()

void ns3::TcpHybla::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
tcbinternal congestion state
segmentsAckedcount of segments acked
rttlast rtt

Reimplemented from ns3::TcpCongestionOps.

Definition at line 81 of file tcp-hybla.cc.

References ns3::TcpSocketState::m_minRtt, NS_LOG_DEBUG, NS_LOG_FUNCTION, and RecalcParam().

Referenced by TcpHyblaIncrementTest::DoRun().

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◆ RecalcParam()

void ns3::TcpHybla::RecalcParam ( const Ptr< TcpSocketState > &  tcb)
private

Recalculate algorithm parameters.

Parameters
tcbthe socket state.

Definition at line 70 of file tcp-hybla.cc.

References ns3::Time::GetMilliSeconds(), ns3::TcpSocketState::m_minRtt, m_rho, m_rRtt, max, NS_ASSERT, NS_LOG_DEBUG, and NS_LOG_FUNCTION.

Referenced by PktsAcked().

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◆ SlowStart()

uint32_t ns3::TcpHybla::SlowStart ( Ptr< TcpSocketState tcb,
uint32_t  segmentsAcked 
)
overrideprotectedvirtual


Tcp NewReno slow start algorithm

Defined in RFC 5681 as

During slow start, a TCP increments cwnd by at most SMSS bytes for each ACK received that cumulatively acknowledges new data. Slow start ends when cwnd exceeds ssthresh (or, optionally, when it reaches it, as noted above) or when congestion is observed. While traditionally TCP implementations have increased cwnd by precisely SMSS bytes upon receipt of an ACK covering new data, we RECOMMEND that TCP implementations increase cwnd, per:

cwnd += min (N, SMSS) (2)

where N is the number of previously unacknowledged bytes acknowledged in the incoming ACK.

The ns-3 implementation respect the RFC definition. Linux does something different:

u32 tcp_slow_start(struct tcp_sock *tp, u32 acked)
  {
    u32 cwnd = tp->snd_cwnd + acked;

    if (cwnd > tp->snd_ssthresh)
      cwnd = tp->snd_ssthresh + 1;
    acked -= cwnd - tp->snd_cwnd;
    tp->snd_cwnd = min(cwnd, tp->snd_cwnd_clamp);

    return acked;
  }

As stated, we want to avoid the case when a cumulative ACK increases cWnd more than a segment size, but we keep count of how many segments we have ignored, and return them.

Parameters
tcbinternal congestion state
segmentsAckedcount of segments acked
Returns
the number of segments not considered for increasing the cWnd

Reimplemented from ns3::TcpNewReno.

Definition at line 94 of file tcp-hybla.cc.

References ns3::TcpSocketState::m_cWnd, m_rho, ns3::TcpSocketState::m_segmentSize, ns3::TcpSocketState::m_ssThresh, min, NS_ASSERT, NS_LOG_FUNCTION, and NS_LOG_INFO.

Member Data Documentation

◆ m_cWndCnt

double ns3::TcpHybla::m_cWndCnt
private

cWnd integer-to-float counter

Definition at line 80 of file tcp-hybla.h.

Referenced by CongestionAvoidance().

◆ m_rho

TracedValue<double> ns3::TcpHybla::m_rho
private

Rho parameter.

Definition at line 78 of file tcp-hybla.h.

Referenced by CongestionAvoidance(), GetTypeId(), RecalcParam(), and SlowStart().

◆ m_rRtt

Time ns3::TcpHybla::m_rRtt
private

Reference RTT.

Definition at line 79 of file tcp-hybla.h.

Referenced by GetTypeId(), and RecalcParam().


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