EthernetCsmaMacPhy

Package: inet.linklayer.ethernet.basic

compound module EthernetCsmaMacPhy

Ethernet MAC layer. MAC performs transmission and reception of frames. See the IEtherMac for the Ethernet MAC layer general information. Doesn’t do encapsulation/decapsulation; see Ieee8022Llc and EthernetEncapsulation 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 the source 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 (Ieee8022Llc and 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 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, the 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 packetCapacity parameter – if this is exceeded, the simulation stops with an error.

Physical layer messaging

Please see Messaging on the physical layer.

See also: EthernetMacPhy, EthernetInterface, IPacketQueue, EthernetEncapsulation, Ieee8022Llc

See also: EthernetMacHeader, Ieee8022LlcHeader, EthernetFcs

EthernetCsmaMacPhy

Usage diagram

Inheritance diagram

Used in compound modules

Name

Type

Description

ExtUpperEthernetInterface

compound module

Provides an Ethernet network interface suitable for emulation. The upper part of the network interface is realized in the real world using a real TAP device of the host computer which is running the simulation.

EthernetInterface

compound module

Represents an Ethernet network interface.

Extends

Name

Type

Description

Module

compound module

Base module for all INET compound modules.

Parameters

Name

Type

Default value

Description

displayStringTextFormat

string

“rate: %b\nsent: %s, rcvd: %r\nqueue: %q, drop: %d”

Determines the text that is written on top of the submodule, supports displaying pars, watches, and module-specific information

interfaceTableModule

string

The path to the InterfaceTable module

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

duplexMode

bool

Selects full-duplex (true) or half-duplex (false) operation

frameBursting

bool

true

Enable/disable frame bursting mode in Gigabit Ethernet

allowNonstandardBitrate

bool

false

Allows any bitrate and uses the first larger bitrate specified parameters

mtu

int

1500B

fcsMode

string

stopOperationExtraTime

double

-1s

Extra time after the lifecycle stop operation finished

stopOperationTimeout

double

2s

Timeout value for the lifecycle stop operation

Properties

Name

Value

Description

class

EthernetCsmaMacPhy

display

i=block/rxtx

lifecycleSupport

Gates

Name

Direction

Size

Description

upperLayerIn

input

To EthernetEncapsulation or IMacRelayUnit

upperLayerOut

output

To EthernetEncapsulation or IMacRelayUnit

phys

inout

To the network

Signals

Name

Type

Unit

Description

backoffSlotsGenerated

long

SlotNumber value emitted

collision

long

packetDropped

Packet

packetReceivedFromLower

inet::Packet

packetReceivedFromUpper

inet::Packet

packetSentToLower

inet::Packet

packetSentToUpper

inet::Packet

receptionEnded

inet::physicallayer::EthernetSignalBase

receptionStarted

inet::physicallayer::EthernetSignalBase

receptionStateChanged

long

Enum=MacReceiveState

rxPausePkUnits

long

rxPkOk

inet::Packet

transmissionEnded

inet::physicallayer::EthernetSignalBase

transmissionStarted

inet::physicallayer::EthernetSignalBase

transmissionStateChanged

long

Enum=MacTransmitState

txPausePkUnits

long

Statistics

Name

Title

Source

Record

Unit

Interpolation Mode

Description

backoffSlotsGenerated

backoff

count,vector

none

collision

collision

count,vector

none

packetDropIncorrectlyReceived

packet drop: incorrectly received

packetDropReasonIsIncorrectlyReceived(packetDropped)

count,sum(packetBytes),vector(packetBytes)

none

packetDropInterfaceDown

packet drop: interface down

packetDropReasonIsInterfaceDown(packetDropped)

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

passedUpPk

packets passed to higher layer

packetSentToUpper

count,”sum(packetBytes)”,”vector(packetBytes)”

none

rxPausePkUnits

pause units received

count,sum,vector

none

rxPkOk

packets received OK

rxPkOk

count,”sum(packetBytes)”,”vector(packetBytes)”

none

txPausePkUnits

pause units sent

count,sum,vector

none

txPk

packets transmitted

packetSentToLower

count,”sum(packetBytes)”,”vector(packetBytes)”

none

Source code

//
// Ethernet MAC layer. MAC performs transmission and reception of frames.
// See the ~IEtherMac for the Ethernet MAC layer general information.
// Doesn't do encapsulation/decapsulation; see ~Ieee8022Llc and ~EthernetEncapsulation 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 the source 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 (~Ieee8022Llc and ~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 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, the 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 `packetCapacity` 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 ~EthernetMacPhy, ~EthernetInterface, ~IPacketQueue, ~EthernetEncapsulation, ~Ieee8022Llc
// @see ~EthernetMacHeader, ~Ieee8022LlcHeader, ~EthernetFcs
//
module EthernetCsmaMacPhy extends Module like IEtherMac
{
    parameters:
        string interfaceTableModule;   // The path to the InterfaceTable module
        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;                    // Selects full-duplex (true) or half-duplex (false) operation
        bool frameBursting = default(true); // Enable/disable frame bursting mode in Gigabit Ethernet
        bool allowNonstandardBitrate = default(false); // Allows any bitrate and uses the first larger bitrate specified parameters
        int mtu @unit(B) = default(1500B);
        string fcsMode @enum("declared","computed");
        @lifecycleSupport;
        double stopOperationExtraTime @unit(s) = default(-1s);    // Extra time after the lifecycle stop operation finished
        double stopOperationTimeout @unit(s) = default(2s);    // Timeout value for the lifecycle stop operation
        @class(EthernetCsmaMacPhy);
        @display("i=block/rxtx");

        @signal[rxPkOk](type=inet::Packet);
        @signal[txPausePkUnits](type=long);
        @signal[rxPausePkUnits](type=long);
        @signal[packetDropped](type=Packet);
        @signal[packetSentToLower](type=inet::Packet);
        @signal[packetReceivedFromLower](type=inet::Packet);
        @signal[packetSentToUpper](type=inet::Packet);
        @signal[packetReceivedFromUpper](type=inet::Packet);
        @signal[collision](type=long);
        @signal[backoffSlotsGenerated](type=long);    // SlotNumber value emitted
        @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[receptionStarted](type=inet::physicallayer::EthernetSignalBase);
        @signal[receptionEnded](type=inet::physicallayer::EthernetSignalBase);

        @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);
        @statistic[collision](title="collision"; record=count,vector; interpolationmode=none);
        @statistic[backoffSlotsGenerated](title="backoff"; record=count,vector; 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/EthernetCsmaMacPhy.ned