EthernetMac

compound module

Ethernet MAC which supports full-duplex operation ONLY. See the IEtherMac for general informations.

Most of today's Ethernet networks are switched, and operate in full-duplex mode. Full-duplex transmission can be used for point-to-point connections only. Since full-duplex connections cannot be shared, collisions are eliminated. This setup eliminates most of the need for the CSMA/CD access control mechanism because there is no need to determine whether the connection is already being used. This allows for a much simpler simulation model for MAC. (In "traditional" Ethernet simulations, most of the code deals with the shared medium and the CSMA/CD mechanism.) EthernetMac implements Ethernet without shared medium and CSMA/CD. (If you need half-duplex operation, see EthernetCsmaMac which is for a full-blown and therefore more complicated Ethernet MAC model.)

EthernetMac performs transmission and reception of frames. It does not do encapsulation/decapsulation; see Ieee8022Llc and EthernetEncapsulation for that.

Supported variations:

10Mb Ethernet (full-duplex mode)
100Mb Ethernet (full-duplex mode)
1Gb Ethernet (full-duplex mode)
10Gb Ethernet (full-duplex mode)
40Gb Ethernet (full-duplex mode)
100Gb Ethernet (full-duplex mode)

Supports all three Ethernet frame types. (It handles EtherFrame message class; specific frame classes (Ethernet-II, IEEE 802.3) are subclassed from that one.) RAW mode (only used by the IPX protocol) is not supported.

Operation

Processing of frames received from higher layers:

if src address in the frame is empty, fill it out
frames get queued up until transmission
transmits the frame when the transmitter is ready
can send PAUSE message if requested by higher layers (PAUSE protocol, used in switches).

Processing of frames incoming from the network:

receive frame from the network
CRC checking (frames with the error bit set are discarded).
respond to PAUSE frames
in promiscuous mode, pass up all received frames; otherwise, only frames with matching MAC addresses and broadcast frames are passed up.

The module does not perform encapsulation or decapsulation of frames -- this is done by higher layers (EthernetEncapsulation).

When a frame is received from the higher layers, it must be an EtherFrame, and with all protocol fields filled out (including the destination MAC address). The source address, if left empty, will be filled in. Then frame is queued and transmitted.

Data frames received from the network are EtherFrames. They are passed to the higher layers without modification. Also, the module properly responds to PAUSE frames, but never sends them by itself -- however, it transmits PAUSE frames received from upper layers. See PAUSE handling for more info.

For more info see Ethernet Model Overview.

Disabling and disconnecting

If the MAC is not connected to the network ("cable unplugged"), it will start up in "disabled" mode. A disabled MAC simply discards any messages it receives. It is currently not supported to dynamically connect/disconnect a MAC.

Queueing

In routers, MAC relies on an external queue module (see IPacketQueue) to model finite buffer, implement QoS and/or RED, and requests packets from this external queue one-by-one.

In hosts, no such queue is used, so MAC contains an internal queue to store packets waiting for transmission. Conceptually, the queue is of infinite size, but for better diagnostics one can specify a hard limit in the queue parameter -- if this is exceeded, the simulation stops with an error.

Physical layer messaging

Please see Messaging on the physical layer.

Inheritance diagram

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

Parameters

Name	Type	Default value	Description
interfaceTableModule	string		The path to the InterfaceTable module
displayStringTextFormat	string	"rate: %b\nsent: %s, rcvd: %r\nqueue: %q, drop: %d"
sendRawBytes	bool	false	when true packets are serialized into a sequence of bytes before sending out
promiscuous	bool	false	if true, all packets are received, otherwise only the ones with matching destination MAC address
duplexMode	bool		must be set to "true", as EthernetMac does not support half-duplex operation (parameter is present to reduce the risk of accidental misconfiguration)
mtu	int	1500B
fcsMode	string
stopOperationExtraTime	double	-1s	extra time after lifecycle stop operation finished
stopOperationTimeout	double	2s	timeout value for lifecycle stop operation

Properties

Name	Value	Description
lifecycleSupport
class	EthernetMac
display	i=block/rxtx

Gates

Name	Direction	Description
upperLayerIn	input	to EthernetEncapsulation or IMacRelayUnit
upperLayerOut	output	to EthernetEncapsulation or IMacRelayUnit
phys	inout	to the network

Signals

Name	Type	Unit
receptionStateChanged	long
rxPkFromHl	inet::Packet
receptionEnded	inet::physicallayer::Signal
packetReceivedFromLower	inet::Packet
packetReceivedFromUpper	inet::Packet
txPausePkUnits	long
txPk	inet::Packet
rxPausePkUnits	long
transmissionStarted	inet::physicallayer::EthernetSignalBase
rxPkOk	inet::Packet
packetDropped	inet::Packet
packetSentToLower	inet::Packet
packetSentToUpper	inet::Packet
transmissionStateChanged	long
transmissionEnded	inet::physicallayer::EthernetSignalBase

Statistics

Name	Title	Source	Record	Interpolation Mode
passedUpPk	packets passed to higher layer	packetSentToUpper	count, sum(packetBytes), vector(packetBytes)	none
packetDropInterfaceDown	packet drop: interface down	packetDropReasonIsInterfaceDown(packetDropped)	count, sum(packetBytes), vector(packetBytes)	none
rxPkOk	packets received OK	rxPkOk	count, sum(packetBytes), vector(packetBytes)	none
packetDropNotAddressedToUs	packet drop: not addressed to us	packetDropReasonIsNotAddressedToUs(packetDropped)	count, sum(packetBytes), vector(packetBytes)	none
packetReceivedFromUpper	packet bytes from higher layer	packetReceivedFromUpper	count, sum(packetBytes), vector(packetBytes)	none
txPausePkUnits	pause units sent		count, sum, vector	none
txPk	packets transmitted	packetSentToLower	count, sum(packetBytes), vector(packetBytes)	none
rxPausePkUnits	pause units received		count, sum, vector	none
packetDropIncorrectlyReceived	packet drop: incorrectly received	packetDropReasonIsIncorrectlyReceived(packetDropped)	count, sum(packetBytes), vector(packetBytes)	none

Scheduled messages (observed)

msg	kind	ctrl	tags	msgname	context
omnetpp::cMessage	100			EndIFG
omnetpp::cMessage	103			EndTransmission

Direct method calls (observed)

call to	function	info
MessageDispatcher	inet::MessageDispatcher::arrived	arrived
ResidenceTimeMeasurer	inet::ResidenceTimeMeasurer::receiveSignal	receptionEnded
ResidenceTimeMeasurer	inet::ResidenceTimeMeasurer::receiveSignal	transmissionStarted
PcapRecorder	inet::PcapRecorder::receiveSignal	packetReceivedFromLower
PcapRecorder	inet::PcapRecorder::receiveSignal	packetSentToLower
ScenarioManager	inet::ScenarioManager::moduleOperationStageCompleted	moduleOperationStageCompleted
EthernetMac	inet::EthernetMac::receiveSignal	POST_MODEL_CHANGE
EthernetMac	inet::EthernetMac::refreshConnection	refreshConnection
EthernetQosQueue	inet::queueing::CompoundPacketQueueBase::pullPacket	pullPacket
EthernetQueue	inet::queueing::PacketQueue::pullPacket	pullPacket
InterfaceTable	inet::InterfaceTable::interfaceChanged	interfaceChanged
DropTailQueue	inet::queueing::PacketQueue::pullPacket	pullPacket
RedDropperQueue	inet::queueing::CompoundPacketQueueBase::pullPacket	pullPacket

Called methods (observed)

function	info	call from
inet::EthernetMac::handleCanPullPacketChanged	handleCanPullPacketChanged	EthernetQueue, DropTailQueue, PacketQueue, PriorityScheduler
inet::EthernetMac::handleOperationStage	handleOperationStage	ScenarioManager
inet::EthernetMac::receiveSignal	POST_MODEL_CHANGE	-=Network=-, ScenarioManager, EthernetMac
inet::EthernetMac::refreshConnection	refreshConnection	EthernetMac

Incoming messages (observed)

gate	msg	kind	ctrl	srcModule	tags
phys$i	EthernetSignal	0		EthernetMac

Outgoing messages (observed)

gate	msg	kind	destModule	tags
phys$o	EthernetSignal	0	EthernetMac
upperLayerOut	Packet	0	EthernetEncapsulation	DispatchProtocolReq, InterfaceInd, MacAddressInd, PacketProtocolTag
upperLayerOut	Packet	0	MultiFieldClassifier	DispatchProtocolReq, InterfaceInd, MacAddressInd, PacketProtocolTag
upperLayerOut	Packet	4	EthernetEncapsulation	DispatchProtocolReq, InterfaceInd, MacAddressInd, PacketProtocolTag

Pull in messages (observed)

gate	msg	kind	srcModule	tags
upperLayerIn	Packet	0	EthernetQueue	InterfaceReq, MacAddressReq, PacketProtocolTag, DirectionTag?, DispatchProtocolInd?, DscpInd?, EcnInd?, EncapsulationProtocolReq?, ErrorRateInd?, HopLimitInd?, Ieee802SapInd?, Ieee802SapReq?, InterfaceInd?, L3AddressInd?, L3AddressReq?, MacAddressInd?, MulticastReq?, NetworkProtocolInd?, SignalPowerInd?, SignalTimeInd?, SnirInd?, SocketReq?, TosInd?, TransportProtocolInd?, Ieee80211ChannelInd?, Ieee80211ModeInd?
upperLayerIn	Packet	0	DropTailQueue	InterfaceReq, MacAddressReq, PacketProtocolTag, DirectionTag?, Ieee802SapReq?
upperLayerIn	Packet	0	PacketQueue	DispatchProtocolInd, EncapsulationProtocolReq, InterfaceInd, InterfaceReq, MacAddressInd, MacAddressReq, NetworkProtocolInd, PacketProtocolTag
upperLayerIn	Packet	0	PriorityScheduler	InterfaceReq, MacAddressReq, PacketProtocolTag, DirectionTag?, DispatchProtocolInd?, EcnInd?, EncapsulationProtocolReq?, Ieee802SapReq?, InterfaceInd?, MacAddressInd?, MulticastReq?, NetworkProtocolInd?, TransportProtocolInd?
upperLayerIn	Packet	4	EthernetQueue	DispatchProtocolInd, EncapsulationProtocolReq, InterfaceInd, InterfaceReq, MacAddressReq, NetworkProtocolInd, PacketProtocolTag

Packet operations (observed)

chunkType	packetAction
	peekDataAsBytes, setBackOffset, trimBack, trimFront
BytesChunk	peekDataAt
EthernetFcs	insertAtBack, peekAtBack, removeAtBack
EthernetMacHeader	peekAtFront
EthernetPadding	insertAtBack
EthernetPhyHeader	insertAtFront, popAtFront

Shared Tagging operations (observed)

tagType	tagAction
	clearTags
DispatchProtocolReq	addTagIfAbsent
InterfaceInd	addTagIfAbsent
MacAddressInd	addTagIfAbsent
PacketProtocolTag	addTag, addTagIfAbsent, removeTag

Source code

//
// Ethernet MAC which supports full-duplex operation ONLY.
// See the ~IEtherMac for general informations.
//
// Most of today's Ethernet networks are switched, and operate
// in full-duplex mode. Full-duplex transmission can be used for
// point-to-point connections only. Since full-duplex connections
// cannot be shared, collisions are eliminated. This setup eliminates
// most of the need for the CSMA/CD access control mechanism because
// there is no need to determine whether the connection is already
// being used. This allows for a much simpler simulation model
// for MAC. (In "traditional" Ethernet simulations, most of the code
// deals with the shared medium and the CSMA/CD mechanism.)
// ~EthernetMac implements Ethernet without shared medium and CSMA/CD.
// (If you need half-duplex operation, see ~EthernetCsmaMac which is for a full-blown
// and therefore more complicated Ethernet MAC model.)
//
// ~EthernetMac performs transmission and reception of frames.
// It does not do encapsulation/decapsulation; see ~Ieee8022Llc and ~EthernetEncapsulation
// for that.
//
// Supported variations:
// - 10Mb Ethernet (full-duplex mode)
// - 100Mb Ethernet (full-duplex mode)
// - 1Gb Ethernet (full-duplex mode)
// - 10Gb Ethernet (full-duplex mode)
// - 40Gb Ethernet (full-duplex mode)
// - 100Gb Ethernet (full-duplex mode)
//
// Supports all three Ethernet frame types. (It handles ~EtherFrame message class;
// specific frame classes (Ethernet-II, IEEE 802.3) are subclassed from that one.)
// RAW mode (only used by the IPX protocol) is not supported.
//
// <b>Operation</b>
//
// Processing of frames received from higher layers:
// - if src address in the frame is empty, fill it out
// - frames get queued up until transmission
// - transmits the frame when the transmitter is ready
// - can send PAUSE message if requested by higher layers (PAUSE protocol,
//   used in switches).
//
// Processing of frames incoming from the network:
// - receive frame from the network
// - CRC checking (frames with the error bit set are discarded).
// - respond to PAUSE frames
// - in promiscuous mode, pass up all received frames;
//   otherwise, only frames with matching MAC addresses and
//   broadcast frames are passed up.
//
// The module does not perform encapsulation or decapsulation of frames --
// this is done by higher layers (~EthernetEncapsulation).
//
// When a frame is received from the higher layers, it must be an ~EtherFrame,
// and with all protocol fields filled out
// (including the destination MAC address). The source address, if left empty,
// will be filled in. Then frame is queued and transmitted.
//
// Data frames received from the network are EtherFrames. They are passed to
// the higher layers without modification.
// Also, the module properly responds to PAUSE frames, but never sends them
// by itself -- however, it transmits PAUSE frames received from upper layers.
// See <a href="ether-pause.html">PAUSE handling</a> for more info.
//
// For more info see <a href="ether-overview.html">Ethernet Model Overview</a>.
//
// <b>Disabling and disconnecting</b>
//
// If the MAC is not connected to the network ("cable unplugged"), it will
// start up in "disabled" mode. A disabled MAC simply discards any messages
// it receives. It is currently not supported to dynamically connect/disconnect
// a MAC.
//
//
// <b>Queueing</b>
//
// In routers, MAC relies on an external queue module (see ~IPacketQueue)
// to model finite buffer, implement QoS and/or RED, and requests packets
// from this external queue one-by-one.
//
// In hosts, no such queue is used, so MAC contains an internal
// queue to store packets waiting for transmission.
// Conceptually, the queue is of infinite size, but for better diagnostics
// one can specify a hard limit in the queue parameter -- if this is
// exceeded, the simulation stops with an error.
//
//
// <b>Physical layer messaging</b>
//
// Please see <a href="physical.html">Messaging on the physical layer</a>.
//
// @see ~EthernetCsmaMac, ~EthernetInterface, ~IPacketQueue, ~EthernetEncapsulation, ~Ieee8022Llc
// @see ~EthernetMacHeader, ~Ieee8022LlcHeader, ~EthernetFcs
//
module EthernetMac like IEtherMac
{
    parameters:
        string interfaceTableModule;        // The path to the InterfaceTable module
        string displayStringTextFormat = default("rate: %b\nsent: %s, rcvd: %r\nqueue: %q, drop: %d");
        bool sendRawBytes = default(false); // when true packets are serialized into a sequence of bytes before sending out
        bool promiscuous = default(false);  // if true, all packets are received, otherwise only the
                                            // ones with matching destination MAC address
        bool duplexMode;                    // must be set to "true", as EthernetMac does not support half-duplex operation
                                            // (parameter is present to reduce the risk of accidental misconfiguration)
        int mtu @unit(B) = default(1500B);
        string fcsMode @enum("declared","computed");
        @lifecycleSupport;
        double stopOperationExtraTime @unit(s) = default(-1s);    // extra time after lifecycle stop operation finished
        double stopOperationTimeout @unit(s) = default(2s);    // timeout value for lifecycle stop operation
        @class(EthernetMac);
        @display("i=block/rxtx");

        @signal[txPk](type=inet::Packet);
        @signal[rxPkOk](type=inet::Packet);
        @signal[txPausePkUnits](type=long);
        @signal[rxPausePkUnits](type=long);
        @signal[rxPkFromHl](type=inet::Packet);
        @signal[packetDropped](type=inet::Packet);
        @signal[packetSentToLower](type=inet::Packet);
        @signal[packetReceivedFromLower](type=inet::Packet);
        @signal[packetSentToUpper](type=inet::Packet);
        @signal[packetReceivedFromUpper](type=inet::Packet);
        @signal[transmissionStateChanged](type=long); // enum=MacTransmitState
        @signal[receptionStateChanged](type=long); // enum=MacReceiveState
        @signal[transmissionStarted](type=inet::physicallayer::EthernetSignalBase);
        @signal[transmissionEnded](type=inet::physicallayer::EthernetSignalBase);
        @signal[receptionEnded](type=inet::physicallayer::Signal);

        @statistic[txPk](title="packets transmitted"; source=packetSentToLower; record=count,"sum(packetBytes)","vector(packetBytes)"; interpolationmode=none);
        @statistic[rxPkOk](title="packets received OK"; source=rxPkOk; record=count,"sum(packetBytes)","vector(packetBytes)"; interpolationmode=none);
        @statistic[passedUpPk](title="packets passed to higher layer"; source=packetSentToUpper; record=count,"sum(packetBytes)","vector(packetBytes)"; interpolationmode=none);
        @statistic[txPausePkUnits](title="pause units sent"; record=count,sum,vector; interpolationmode=none);
        @statistic[rxPausePkUnits](title="pause units received"; record=count,sum,vector; interpolationmode=none);
        @statistic[packetReceivedFromUpper](title="packet bytes from higher layer"; source=packetReceivedFromUpper; record=count,"sum(packetBytes)","vector(packetBytes)"; interpolationmode=none);
        @statistic[packetDropIncorrectlyReceived](title="packet drop: incorrectly received"; source=packetDropReasonIsIncorrectlyReceived(packetDropped); record=count,sum(packetBytes),vector(packetBytes); interpolationmode=none);
        @statistic[packetDropInterfaceDown](title="packet drop: interface down"; source=packetDropReasonIsInterfaceDown(packetDropped); record=count,sum(packetBytes),vector(packetBytes); interpolationmode=none);
        @statistic[packetDropNotAddressedToUs](title="packet drop: not addressed to us"; source=packetDropReasonIsNotAddressedToUs(packetDropped); record=count,sum(packetBytes),vector(packetBytes); interpolationmode=none);

    gates:
        input upperLayerIn @labels(EtherFrame);    // to ~EthernetEncapsulation or ~IMacRelayUnit
        output upperLayerOut @labels(EtherFrame);  // to ~EthernetEncapsulation or ~IMacRelayUnit
        inout phys @labels(EthernetSignal);        // to the network
}

File: src/inet/linklayer/ethernet/basic/EthernetMac.ned