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

An implementation of TCP HighSpeed. More...

#include "tcp-highspeed.h"

+ Inheritance diagram for ns3::TcpHighSpeed:
+ Collaboration diagram for ns3::TcpHighSpeed:

Public Member Functions

 TcpHighSpeed (void)
 Create an unbound tcp socket. More...
 
 TcpHighSpeed (const TcpHighSpeed &sock)
 Copy constructor. More...
 
virtual ~TcpHighSpeed (void)
 
virtual Ptr< TcpCongestionOpsFork ()
 Copy the congestion control algorithm across sockets. More...
 
virtual std::string GetName () const
 Get the name of the congestion control algorithm. More...
 
virtual uint32_t GetSsThresh (Ptr< const TcpSocketState > tcb, uint32_t bytesInFlight)
 Get slow start threshold following HighSpeed principles. More...
 
- Public Member Functions inherited from ns3::TcpNewReno
 TcpNewReno ()
 
 TcpNewReno (const TcpNewReno &sock)
 Copy constructor. More...
 
 ~TcpNewReno ()
 
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...
 
virtual void Init (Ptr< TcpSocketState > tcb)
 Set configuration required by congestion control algorithm. 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...
 
template<>
Ptr< ObjectGetObject () const
 
template<>
Ptr< ObjectGetObject (TypeId tid) const
 
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 uint32_t TableLookupA (uint32_t w)
 Lookup table for the coefficient a (from RFC 3649) More...
 
static double TableLookupB (uint32_t w)
 Lookup table for the coefficient b (from RFC 3649) 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)
 Congestion avoidance of TcpHighSpeed. More...
 
- Protected Member Functions inherited from ns3::TcpNewReno
virtual uint32_t SlowStart (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked)
 
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 Attributes

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

Additional Inherited Members

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

Config Paths

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

  • "/NodeList/[i]/$ns3::TcpL4Protocol/SocketList/[i]/CongestionOps/$ns3::TcpHighSpeed"
  • "/NodeList/[i]/$ns3::TcpL4Protocol/SocketList/[i]/CongestionOps/$ns3::TcpNewReno/$ns3::TcpHighSpeed"

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 49 of file tcp-highspeed.h.

Constructor & Destructor Documentation

◆ TcpHighSpeed() [1/2]

ns3::TcpHighSpeed::TcpHighSpeed ( void  )

Create an unbound tcp socket.

Definition at line 41 of file tcp-highspeed.cc.

References NS_LOG_FUNCTION.

◆ TcpHighSpeed() [2/2]

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

Copy constructor.

Parameters
sockthe object to copy

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

References NS_LOG_FUNCTION.

◆ ~TcpHighSpeed()

ns3::TcpHighSpeed::~TcpHighSpeed ( void  )
virtual

Definition at line 55 of file tcp-highspeed.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CongestionAvoidance()

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

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
tcbinternal congestion state
segmentsAckedcount of segments acked

Reimplemented from ns3::TcpNewReno.

Definition at line 99 of file tcp-highspeed.cc.

References ns3::TcpSocketState::GetCwndInSegments(), m_ackCnt, ns3::TcpSocketState::m_cWnd, ns3::TcpSocketState::m_segmentSize, ns3::TcpSocketState::m_ssThresh, NS_LOG_FUNCTION, NS_LOG_INFO, and TableLookupA().

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◆ Fork()

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

Copy the congestion control algorithm across sockets.

Returns
a pointer of the copied object

Reimplemented from ns3::TcpNewReno.

Definition at line 61 of file tcp-highspeed.cc.

◆ GetName()

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

Get the name of the congestion control algorithm.

Returns
A string identifying the name

Reimplemented from ns3::TcpNewReno.

Definition at line 127 of file tcp-highspeed.cc.

◆ GetSsThresh()

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

Get slow start threshold following HighSpeed principles.

Parameters
tcbinternal congestion state
bytesInFlightBytes in flight
Returns
the slow start threshold value

Reimplemented from ns3::TcpNewReno.

Definition at line 141 of file tcp-highspeed.cc.

References max, NS_LOG_DEBUG, NS_LOG_FUNCTION, and TableLookupB().

Referenced by TcpHighSpeedDecrementTest::DoRun().

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◆ GetTypeId()

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

Get the type ID.

Returns
the object TypeId

Definition at line 31 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
wWindow value (in packets)
Returns
the coefficient a

Definition at line 158 of file tcp-highspeed.cc.

Referenced by CongestionAvoidance().

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◆ TableLookupB()

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

Lookup table for the coefficient b (from RFC 3649)

Parameters
wWindow value (in packets)
Returns
the coefficient b

Definition at line 459 of file tcp-highspeed.cc.

Referenced by 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 99 of file tcp-highspeed.h.

Referenced by CongestionAvoidance().


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