EtherMAC

simple module

Ethernet MAC layer. MAC performs transmission and reception of frames. See the IEtherMAC for the Ethernet MAC layer general informations. Doesn't do encapsulation/decapsulation; see EtherLLC and EtherEncap for that.

Supported variations:

10Mb Ethernet (duplex and half-duplex, coaxial cable or twisted pair)
100Mb Ethernet (duplex and half-duplex)
1Gb Ethernet (duplex and half-duplex)
10Gb Ethernet
40Gb Ethernet
100Gb Ethernet

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.

Expected environment:

phys$i and phys$o should be connected to the "network"
upperLayerIn and upperLayerOut are usually connected to EtherLLC (in hosts) or MACRelayUnit (in a switch)

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
transmit according to the CSMA/CD protocol
can send PAUSE message if requested by higher layers (PAUSE protocol, used in switches).

Processing of frames incoming from the network:

receive according to the CSMA/CD protocol
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 (EtherLLC or EtherEncap).

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 according to the CSMA/CD protocol.

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 IOutputQueue) 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 named txQueue to queue up packets waiting for transmission. Conceptually, txQueue is of infinite size, but for better diagnostics one can specify a hard limit in the txQueueLimit 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
promiscuous	bool	false	if true, all packets are received, otherwise only the ones with matching destination MAC address
address	string	"auto"	MAC address as hex string (12 hex digits), or "auto". "auto" values will be replaced by a generated MAC address in init stage 0.
duplexMode	bool	true	selects full-duplex (true) or half-duplex (false) operation
txQueueLimit	int	1000	maximum number of frames queued up for transmission in the internal queue (only used if queueModule==""); additional frames cause a runtime error
queueModule	string	""	name of optional external queue module
frameBursting	bool	true	enable/disable frame bursting mode in Gigabit Ethernet
mtu	int	1500B

Properties

Name	Value	Description
display	i=block/rxtx

Gates

Name	Direction	Description
upperLayerIn	input	to EtherLLC or EtherEncap or IMACRelayUnit
upperLayerOut	output	to EtherLLC or EtherEncap or IMACRelayUnit
phys	inout	to physical layer or the network

Signals

Name	Type	Unit
rxPkFromHL	inet::EtherFrame
packetReceivedFromLower	inet::EtherFrame
packetReceivedFromUpper	inet::EtherFrame
backoff	long
txPausePkUnits	inet::long
txPk	inet::EtherFrame
dropPkBitError	inet::EtherFrame
rxPausePkUnits	inet::long
dropPkFromHLIfaceDown	inet::EtherFrame
dropPkNotForUs	inet::EtherFrame
collision	long
rxPkOk	inet::EtherFrame
transmitState	long
receiveState	long
packetSentToLower	inet::EtherFrame
packetSentToUpper	inet::EtherFrame
dropPkIfaceDown	inet::EtherFrame

Statistics

Name	Title	Source	Record	Interpolation Mode
passedUpPk	packets passed to higher layer	packetSentToUpper	count, sum(packetBytes), vector(packetBytes)	none
rxPkFromHL	packet bytes from higher layer	rxPkFromHL	count, sum(packetBytes), vector(packetBytes)	none
droppedPkBitError	packets dropped/bit error	dropPkBitError	count, sum(packetBytes), vector(packetBytes)	none
collision	collision		count, vector	none
droppedPkIfaceDown	packets dropped/interface down	dropPkIfaceDown	count, sum(packetBytes), vector(packetBytes)	none
rxPkOk	packets received OK	rxPkOk	count, sum(packetBytes), vector(packetBytes)	none
backoff	backoff		count, vector	none
txPausePkUnits	pause units sent		count, sum, vector	none
droppedPkNotForUs	packets dropped/not for us	dropPkNotForUs	count, sum(packetBytes), vector(packetBytes)	none
txPk	packets transmitted	txPk	count, sum(packetBytes), vector(packetBytes)	none
rxPausePkUnits	pause units received		count, sum, vector	none

Source code

//
// Ethernet MAC layer. MAC performs transmission and reception of frames.
// See the ~IEtherMAC for the Ethernet MAC layer general informations.
// Doesn't do encapsulation/decapsulation; see ~EtherLLC and ~EtherEncap for
// that.
//
// Supported variations:
// - 10Mb Ethernet (duplex and half-duplex, coaxial cable or twisted pair)
// - 100Mb Ethernet (duplex and half-duplex)
// - 1Gb Ethernet (duplex and half-duplex)
// - 10Gb Ethernet
// - 40Gb Ethernet
// - 100Gb Ethernet
//
// 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.
//
// Expected environment:
// - phys$i and phys$o should be connected to the "network"
// - upperLayerIn and upperLayerOut are usually connected to ~EtherLLC (in hosts)
//   or ~MACRelayUnit (in a switch)
//
// <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
// - transmit according to the CSMA/CD protocol
// - can send PAUSE message if requested by higher layers (PAUSE protocol,
//   used in switches).
//
// Processing of frames incoming from the network:
// - receive according to the CSMA/CD protocol
// - 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 (~EtherLLC or ~EtherEncap).
//
// 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 according
// to the CSMA/CD protocol.
//
// 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 ~IOutputQueue)
// 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 named txQueue to queue up packets waiting for transmission.
// Conceptually, txQueue is of infinite size, but for better diagnostics
// one can specify a hard limit in the txQueueLimit 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 ~EtherMACFullDuplex, ~EthernetInterface, ~IOutputQueue, ~EtherEncap, ~EtherLLC
// @see ~EtherFrame, ~EthernetIIFrame, ~EtherFrameWithLLC, ~Ieee802Ctrl
//
simple EtherMAC like IEtherMAC
{
    parameters:
        string interfaceTableModule;   // The path to the InterfaceTable module
        bool promiscuous = default(false);  // if true, all packets are received, otherwise only the
                                            // ones with matching destination MAC address
        string address @mutable = default("auto");   // MAC address as hex string (12 hex digits), or
                                                     // "auto". "auto" values will be replaced by
                                                     // a generated MAC address in init stage 0.
        bool duplexMode = default(true);    // selects full-duplex (true) or half-duplex (false) operation
        int txQueueLimit = default(1000);   // maximum number of frames queued up for transmission in the internal queue (only used if queueModule==""); additional frames cause a runtime error
        string queueModule = default("");   // name of optional external queue module
        bool frameBursting = default(true); // enable/disable frame bursting mode in Gigabit Ethernet
        int mtu @unit("B") = default(1500B);
        @display("i=block/rxtx");

        @signal[txPk](type=inet::EtherFrame);
        @signal[rxPkOk](type=inet::EtherFrame);
        @signal[txPausePkUnits](type=inet::long);
        @signal[rxPausePkUnits](type=inet::long);
        @signal[rxPkFromHL](type=inet::EtherFrame);
        @signal[dropPkNotForUs](type=inet::EtherFrame);
        @signal[dropPkBitError](type=inet::EtherFrame);
        @signal[dropPkFromHLIfaceDown](type=inet::EtherFrame);
        @signal[dropPkIfaceDown](type=inet::EtherFrame);        // emitted at begin of receiving
        @signal[packetSentToLower](type=inet::EtherFrame);
        @signal[packetReceivedFromLower](type=inet::EtherFrame);
        @signal[packetSentToUpper](type=inet::EtherFrame);
        @signal[packetReceivedFromUpper](type=inet::EtherFrame);
        @signal[collision](type=long);
        @signal[backoff](type=long);
        @signal[transmitState](type=long); // enum=MACTransmitState
        @signal[receiveState](type=long); // enum=MACReceiveState

        @statistic[txPk](title="packets transmitted"; source=txPk; 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[rxPkFromHL](title="packet bytes from higher layer"; source=rxPkFromHL; record=count,"sum(packetBytes)","vector(packetBytes)"; interpolationmode=none);
        @statistic[droppedPkIfaceDown](title="packets dropped/interface down"; source=dropPkIfaceDown; record=count,"sum(packetBytes)","vector(packetBytes)"; interpolationmode=none);
        @statistic[droppedPkBitError](title="packets dropped/bit error"; source=dropPkBitError; record=count,"sum(packetBytes)","vector(packetBytes)"; interpolationmode=none);
        @statistic[droppedPkNotForUs](title="packets dropped/not for us"; source=dropPkNotForUs; record=count,"sum(packetBytes)","vector(packetBytes)"; interpolationmode=none);
        @statistic[collision](title="collision"; record=count,vector; interpolationmode=none);
        @statistic[backoff](title="backoff"; record=count,vector; interpolationmode=none);

    gates:
        input upperLayerIn @labels(EtherFrame);    // to ~EtherLLC or ~EtherEncap or ~IMACRelayUnit
        output upperLayerOut @labels(EtherFrame);  // to ~EtherLLC or ~EtherEncap or ~IMACRelayUnit
        inout phys @labels(EtherFrame); // to physical layer or the network
}

File: src/inet/linklayer/ethernet/EtherMAC.ned