CreditBasedGate

simple module

This module is a packet gate that operates based on the number of credits it contains. The gate is open if the number of credits is greater than the configured transmit credit limit, it is closed otherwise. The module attaches a CreditGateTag to all packets that pass through. The attached tag allows the gate module to determine if a packet belongs to it when the packet is eventually transmitted.

The number of credits decreases if a packet that passed through this gate is currently being transmitted by the network interface. Otherwise, the number of credits increases below the transmit credit limit or if there are packets waiting to be transmitted. Besides, the number of credits immediately drops down to the transmit credit limit if no more packets are available after the network interface finishes a transmission from this gate.

This module is part of the credit based shaper infrastructure.

See also: CreditGateTag, PacketQueue

Inheritance diagram

The following diagram shows inheritance relationships for this type. Unresolved types are missing from the diagram.

Known subclasses

Name	Type	Description
Ieee8021qCreditBasedGate	simple module	This module is a packet gate that can be used to implement the IEEE 802.1q credit based shaper algorithm in combination with a packet queue.

Extends

Name	Type	Description
PacketGateBase	simple module	This is a base module for various packet gate modules.

Parameters

Name	Type	Default value	Description
displayStringTextFormat	string	"contains %n cr\nserved %p pk (%l)"	determines the text that is written on top of the submodule
bitrate	double	nan bps
extraLength	int	0b
extraDuration	double	0s
idleCreditGainRate	double		rate of credit increase while the packets that passed through this gate don't use the physical channel
transmitCreditSpendRate	double		rate of credit decrease while the packets that passed through this gate use the physical channel
initialCredit	double	0	initial number of credits
transmitCreditLimit	double	0	credit limit above which the gate is open
minCredit	double	-inf	minimum number of credits
maxCredit	double	inf	maximum number of credits
accumulateCreditInGuardBand	bool	false	whether credit increases during implicit guard band when no packets can be sent anymore

Properties

Name	Value	Description
display	i=block/cogwheel
class	CreditBasedGate

Gates

Name	Direction	Size	Description
in	input
out	output

Signals

Name	Type	Unit
creditsChanged	double

Statistics

Name	Title	Source	Record	Unit	Interpolation Mode
numCredits	number of credits	creditsChanged	vector	cr	linear

Source code

//
// This module is a packet gate that operates based on the number of credits
// it contains. The gate is open if the number of credits is greater than the
// configured transmit credit limit, it is closed otherwise. The module attaches
// a ~CreditGateTag to all packets that pass through. The attached tag allows
// the gate module to determine if a packet belongs to it when the packet is
// eventually transmitted.
//
// The number of credits decreases if a packet that passed through this gate is
// currently being transmitted by the network interface. Otherwise, the number
// of credits increases below the transmit credit limit or if there are packets
// waiting to be transmitted. Besides, the number of credits immediately drops
// down to the transmit credit limit if no more packets are available after the
// network interface finishes a transmission from this gate.
//
// This module is part of the credit based shaper infrastructure.
//
// @see ~CreditGateTag, ~PacketQueue
//
simple CreditBasedGate extends PacketGateBase like IPacketGate
{
    parameters:
        double idleCreditGainRate; // rate of credit increase while the packets that passed through this gate don't use the physical channel
        double transmitCreditSpendRate; // rate of credit decrease while the packets that passed through this gate use the physical channel
        double initialCredit = default(0); // initial number of credits
        double transmitCreditLimit = default(0); // credit limit above which the gate is open
        double minCredit = default(-inf); // minimum number of credits
        double maxCredit = default(inf); // maximum number of credits
        bool accumulateCreditInGuardBand = default(false); // whether credit increases during implicit guard band when no packets can be sent anymore
        displayStringTextFormat = default("contains %n cr\nserved %p pk (%l)"); // determines display string text above the submodule
        @class(CreditBasedGate);
        @signal[creditsChanged](type=double);
        @statistic[numCredits](title="number of credits"; source=creditsChanged; record=vector; unit=cr; interpolationmode=linear);
}

File: src/inet/queueing/gate/CreditBasedGate.ned