Implementation of the TCP Hybla algorithm. More...
#include "tcp-hybla.h"
Public Member Functions | |
TcpHybla () | |
Create an unbound tcp socket. More... | |
TcpHybla (const TcpHybla &sock) | |
Copy constructor. More... | |
~TcpHybla () override | |
Ptr< TcpCongestionOps > | Fork () override |
Copy the congestion control algorithm across sockets. More... | |
std::string | GetName () const override |
Get the name of the congestion control algorithm. More... | |
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 () override | |
uint32_t | GetSsThresh (Ptr< const TcpSocketState > tcb, uint32_t bytesInFlight) override |
Get the slow start threshold after a loss event. More... | |
void | IncreaseWindow (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override |
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... | |
~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. 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[[maybe_unused]]) |
Set configuration required by congestion control algorithm. More... | |
Public Member Functions inherited from ns3::Object | |
Object () | |
Constructor. More... | |
~Object () override | |
Destructor. More... | |
void | AggregateObject (Ptr< Object > other) |
Aggregate two Objects together. More... | |
void | Dispose () |
Dispose of this Object. More... | |
AggregateIterator | GetAggregateIterator () const |
Get an iterator to the Objects aggregated to this one. More... | |
TypeId | GetInstanceTypeId () const override |
Get the most derived TypeId for this Object. More... | |
template<typename T > | |
Ptr< T > | GetObject () const |
Get a pointer to the requested aggregated Object. More... | |
template<> | |
Ptr< Object > | GetObject () const |
Specialization of () for objects of type ns3::Object. More... | |
template<typename T > | |
Ptr< T > | GetObject (TypeId tid) const |
Get a pointer to the requested aggregated Object by TypeId. More... | |
template<> | |
Ptr< Object > | GetObject (TypeId tid) const |
Specialization of (TypeId tid) for objects of type ns3::Object. More... | |
void | Initialize () |
Invoke DoInitialize on all Objects aggregated to this one. More... | |
bool | IsInitialized () 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[[maybe_unused]]) | |
Copy constructor. More... | |
uint32_t | GetReferenceCount () const |
Get the reference count of the object. More... | |
SimpleRefCount & | operator= (const SimpleRefCount &o[[maybe_unused]]) |
Assignment operator. More... | |
void | Ref () const |
Increment the reference count. More... | |
void | Unref () 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 errors. 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 () |
Get the type ID. More... | |
Static Public Member Functions inherited from ns3::TcpNewReno | |
static TypeId | GetTypeId () |
Get the type ID. More... | |
Static Public Member Functions inherited from ns3::TcpCongestionOps | |
static TypeId | GetTypeId () |
Get the type ID. More... | |
Static Public Member Functions inherited from ns3::Object | |
static TypeId | GetTypeId () |
Register this type. More... | |
Static Public Member Functions inherited from ns3::ObjectBase | |
static TypeId | GetTypeId () |
Get the type ID. More... | |
Protected Member Functions | |
void | CongestionAvoidance (Ptr< TcpSocketState > tcb, uint32_t segmentsAcked) override |
NewReno congestion avoidance. More... | |
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 () |
Destructor implementation. More... | |
virtual void | DoInitialize () |
Initialize() implementation. More... | |
virtual void | NotifyNewAggregate () |
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 () |
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 | |
Related Functions inherited from ns3::ObjectBase | |
static TypeId | GetObjectIid () |
Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly. More... | |
Implementation of the TCP Hybla algorithm.
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
Definition at line 47 of file tcp-hybla.h.
ns3::TcpHybla::TcpHybla | ( | ) |
Create an unbound tcp socket.
Definition at line 50 of file tcp-hybla.cc.
References NS_LOG_FUNCTION.
ns3::TcpHybla::TcpHybla | ( | const TcpHybla & | sock | ) |
Copy constructor.
sock | the object to copy |
Definition at line 58 of file tcp-hybla.cc.
References NS_LOG_FUNCTION.
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override |
Definition at line 66 of file tcp-hybla.cc.
References NS_LOG_FUNCTION.
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overrideprotectedvirtual |
NewReno congestion avoidance.
During congestion avoidance, cwnd is incremented by roughly 1 full-sized segment per round-trip time (RTT).
tcb | internal congestion state |
segmentsAcked | count of segments acked |
Reimplemented from ns3::TcpNewReno.
Definition at line 125 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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overridevirtual |
Copy the congestion control algorithm across sockets.
Reimplemented from ns3::TcpNewReno.
Definition at line 166 of file tcp-hybla.cc.
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overridevirtual |
Get the name of the congestion control algorithm.
Reimplemented from ns3::TcpNewReno.
Definition at line 172 of file tcp-hybla.cc.
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static |
Get the type ID.
Definition at line 32 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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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.
tcb | internal congestion state |
segmentsAcked | count of segments acked |
rtt | last rtt |
Reimplemented from ns3::TcpCongestionOps.
Definition at line 83 of file tcp-hybla.cc.
References ns3::TcpSocketState::m_minRtt, NS_LOG_DEBUG, NS_LOG_FUNCTION, and RecalcParam().
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private |
Recalculate algorithm parameters.
tcb | the socket state. |
Definition at line 72 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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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.
tcb | internal congestion state |
segmentsAcked | count of segments acked |
Reimplemented from ns3::TcpNewReno.
Definition at line 95 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.
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private |
cWnd integer-to-float counter
Definition at line 81 of file tcp-hybla.h.
Referenced by CongestionAvoidance().
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private |
Rho parameter.
Definition at line 79 of file tcp-hybla.h.
Referenced by CongestionAvoidance(), GetTypeId(), RecalcParam(), and SlowStart().
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private |
Reference RTT.
Definition at line 80 of file tcp-hybla.h.
Referenced by GetTypeId(), and RecalcParam().