An implementation of TCP HighSpeed. More...
#include "tcp-highspeed.h"
Public Member Functions | |
TcpHighSpeed () | |
Create an unbound tcp socket. | |
TcpHighSpeed (const TcpHighSpeed &sock) | |
Copy constructor. | |
~TcpHighSpeed () 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 slow start threshold following HighSpeed principles. | |
Public Member Functions inherited from ns3::TcpNewReno | |
TcpNewReno () | |
TcpNewReno (const TcpNewReno &sock) | |
Copy constructor. | |
~TcpNewReno () 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 |
Try to increase the cWnd following the NewReno specification. | |
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 bool | HasCongControl () const |
Returns true when Congestion Control Algorithm implements CongControl. | |
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 uint32_t | TableLookupA (uint32_t w) |
Lookup table for the coefficient a (from RFC 3649) | |
static double | TableLookupB (uint32_t w) |
Lookup table for the coefficient b (from RFC 3649) | |
Static Public Member Functions inherited from ns3::TcpNewReno | |
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. | |
Protected Member Functions | |
void | CongestionAvoidance (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override |
Congestion avoidance of TcpHighSpeed. | |
Protected Member Functions inherited from ns3::TcpNewReno | |
virtual uint32_t | SlowStart (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) |
Tcp NewReno slow start algorithm. | |
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. | |
Private Attributes | |
uint32_t | m_ackCnt |
Number of received ACK, corrected with the coefficient a. | |
Additional Inherited Members | |
Related Symbols inherited from ns3::ObjectBase | |
static TypeId | GetObjectIid () |
Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly. | |
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
ns3::TcpHighSpeed is accessible through the following paths with Config::Set and Config::Connect:
No Attributes are defined for this type.
No TraceSources are defined for this type.
Group: Internet
Size of this type is 56 bytes (on a 64-bit architecture).
Definition at line 38 of file tcp-highspeed.h.
ns3::TcpHighSpeed::TcpHighSpeed | ( | ) |
Create an unbound tcp socket.
Definition at line 30 of file tcp-highspeed.cc.
References NS_LOG_FUNCTION.
ns3::TcpHighSpeed::TcpHighSpeed | ( | const TcpHighSpeed & | sock | ) |
Copy constructor.
sock | the object to copy |
Definition at line 37 of file tcp-highspeed.cc.
References NS_LOG_FUNCTION.
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override |
Definition at line 44 of file tcp-highspeed.cc.
References NS_LOG_FUNCTION.
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overrideprotectedvirtual |
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.
tcb | internal congestion state |
segmentsAcked | count of segments acked |
Reimplemented from ns3::TcpNewReno.
Definition at line 88 of file tcp-highspeed.cc.
References m_ackCnt, NS_LOG_FUNCTION, NS_LOG_INFO, and TableLookupA().
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overridevirtual |
Copy the congestion control algorithm across sockets.
Implements ns3::TcpCongestionOps.
Definition at line 50 of file tcp-highspeed.cc.
References ns3::Object::CopyObject.
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overridevirtual |
Get the name of the congestion control algorithm.
Implements ns3::TcpCongestionOps.
Definition at line 116 of file tcp-highspeed.cc.
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overridevirtual |
Get slow start threshold following HighSpeed principles.
tcb | internal congestion state |
bytesInFlight | Bytes in flight |
Implements ns3::TcpCongestionOps.
Definition at line 130 of file tcp-highspeed.cc.
References NS_LOG_DEBUG, NS_LOG_FUNCTION, and TableLookupB().
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static |
Get the type ID.
Definition at line 21 of file tcp-highspeed.cc.
References ns3::TypeId::SetParent().
Lookup table for the coefficient a (from RFC 3649)
w | Window value (in packets) |
Definition at line 145 of file tcp-highspeed.cc.
Referenced by CongestionAvoidance(), and TcpHighSpeedIncrementTest::DoRun().
Lookup table for the coefficient b (from RFC 3649)
w | Window value (in packets) |
Definition at line 444 of file tcp-highspeed.cc.
Referenced by TcpHighSpeedDecrementTest::DoRun(), and GetSsThresh().
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private |
Number of received ACK, corrected with the coefficient a.
Definition at line 87 of file tcp-highspeed.h.
Referenced by CongestionAvoidance().