Msg File src/inet/linklayer/ethernet/common/EthernetMacHeader.msg

Name	Type	Description
EthernetMacAddressFields	class	This class represents the source and destination address fields of an IEEE 802.3 Ethernet MAC header as defined in the sections 3.2.3 Address fields, 3.2.4 Destination Address field, 3.2.5 Source Address field of the IEEE Std 802.3-2018, IEEE Standard for Ethernet.
EthernetTypeOrLengthField	class	This class represents the EtherType field of an IEEE 802.3 Ethernet MAC header as defined in the section 3.2.6 Length/Type field of the IEEE Std 802.3-2018, IEEE Standard for Ethernet.
EthernetMacHeader	class	This class represents an IEEE 802.3 Ethernet MAC header as defined in the section 3.2 Elements of the MAC frame and packet of the IEEE Std 802.3-2018, IEEE Standard for Ethernet.
EthernetPadding	class	This class represents the variable length padding part of an Ethernet frame as defined in the section 3.2.8 Pad field of the IEEE Std 802.3-2018, IEEE Standard for Ethernet.
EthernetFcs	class	This class represents an Ethernet FCS as defined in the section 3.2.9 Frame Check Sequence (FCS) field of the IEEE Std 802.3-2018, IEEE Standard for Ethernet.
EthernetFragmentFcs	class	This class represents an Ethernet fragment FCS as defined in the section 3.2.9 Frame Check Sequence (FCS) field of the IEEE Std 802.3-2018, IEEE Standard for Ethernet.

Source code

//
// Copyright (C) 2020 OpenSim Ltd.
//
// SPDX-License-Identifier: LGPL-3.0-or-later
//

import inet.common.INETDefs;
import inet.common.packet.chunk.Chunk;
import inet.linklayer.common.EtherType;
import inet.linklayer.common.FcsMode;
import inet.linklayer.common.MacAddress;

namespace inet;

//
// This class represents the source and destination address fields of an IEEE
// 802.3 Ethernet MAC header as defined in the sections 3.2.3 Address fields,
// 3.2.4 Destination Address field, 3.2.5 Source Address field of the IEEE Std
// 802.3-2018, IEEE Standard for Ethernet.
//
//  0                   1                   2                   3                   4
//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
// +-----------------------------------------------------------------------------------------------+
// |                                      Destination Address                                      |
// +-----------------------------------------------------------------------------------------------+
// |                                        Source Address                                         |
// +-------------------------------+---------------------------------------------------------------+
//
class EthernetMacAddressFields extends FieldsChunk
{
    chunkLength = B(12); // B(6) + B(6)
    // TODO rename to destinationAddress
    MacAddress dest; // The Destination Address field specifies the station(s) for which the MAC frame is intended. It may be an individual or multicast (including broadcast) address.
    // TODO rename to sourceAddress
    MacAddress src; // The Source Address field specifies the station sending the MAC frame.
}

//
// This class represents the EtherType field of an IEEE 802.3 Ethernet MAC header
// as defined in the section 3.2.6 Length/Type field of the IEEE Std 802.3-2018,
// IEEE Standard for Ethernet.
//
//  0                   1
//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
// +-------------------------------+
// |        EtherType/Length       |
// +-------------------------------+
//
class EthernetTypeOrLengthField extends FieldsChunk
{
    chunkLength = B(2);
    uint16_t typeOrLength; // This two-octet field takes one of two meanings, depending on its numeric value. For numerical evaluation,
                           // the first octet is the most significant octet of this field.
                           // a) If the value of this field is less than or equal to 1500 decimal (05DC hexadecimal), then the Length/
                           //    Type field indicates the number of MAC client data octets contained in the subsequent MAC Client
                           //    Data field of the basic frame (Length interpretation).
                           // b) If the value of this field is greater than or equal to 1536 decimal (0600 hexadecimal), then the
                           //    Length/Type field indicates the Ethertype of the MAC client protocol (Type interpretation).
}

//
// This class represents an IEEE 802.3 Ethernet MAC header as defined in the
// section 3.2 Elements of the MAC frame and packet of the IEEE Std 802.3-2018,
// IEEE Standard for Ethernet.
//
//  0                   1                   2                   3                   4
//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
// +-----------------------------------------------------------------------------------------------+
// |                                      Destination Address                                      |
// +-----------------------------------------------------------------------------------------------+
// |                                        Source Address                                         |
// +-------------------------------+---------------------------------------------------------------+
// |           EtherType           |
// +-------------------------------+
//
class EthernetMacHeader extends EthernetMacAddressFields
{
    chunkLength = B(14); // B(6) + B(6) + B(2)
    uint16_t typeOrLength; // This two-octet field takes one of two meanings, depending on its numeric value. For numerical evaluation,
                           // the first octet is the most significant octet of this field.
                           // a) If the value of this field is less than or equal to 1500 decimal (05DC hexadecimal), then the Length/
                           //    Type field indicates the number of MAC client data octets contained in the subsequent MAC Client
                           //    Data field of the basic frame (Length interpretation).
                           // b) If the value of this field is greater than or equal to 1536 decimal (0600 hexadecimal), then the
                           //    Length/Type field indicates the Ethertype of the MAC client protocol (Type interpretation).
}

cplusplus {{
    inline bool isEth2Header(const EthernetMacHeader& hdr) { return isEth2Type(hdr.getTypeOrLength()); }
    inline bool isIeee8023Header(const EthernetMacHeader& hdr) { return isIeee8023Length(hdr.getTypeOrLength()); }
}}

//
// This class represents the variable length padding part of an Ethernet frame
// as defined in the section 3.2.8 Pad field of the IEEE Std 802.3-2018, IEEE
// Standard for Ethernet.
//
//  0                   1
//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 ...
// +-------------------------------+
// |   Non-zero number of 0 bits   |
// +-------------------------------+
//
class EthernetPadding extends FieldsChunk
{
}

//
// This class represents an Ethernet FCS as defined in the section 3.2.9 Frame
// Check Sequence (FCS) field of the IEEE Std 802.3-2018, IEEE Standard for
// Ethernet.
//
//  0                   1                   2                   3
//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
// +---------------------------------------------------------------+
// |                              FCS                              |
// +---------------------------------------------------------------+
//
class EthernetFcs extends FieldsChunk
{
    chunkLength = B(4);
    uint32_t fcs; // actual value may be omitted depending on the selected fcsMode

    FcsMode fcsMode = FCS_MODE_UNDEFINED; // meta information, not represented directly in the frame
}

//
// This class represents an Ethernet fragment FCS as defined in the section 3.2.9
// Frame Check Sequence (FCS) field of the IEEE Std 802.3-2018, IEEE Standard for
// Ethernet.
//
//  0                   1                   2                   3
//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
// +---------------------------------------------------------------+
// |                              FCS                              |
// +---------------------------------------------------------------+
//
class EthernetFragmentFcs extends EthernetFcs
{
    bool mCrc; // meta information, not represented directly in the frame
}