ETHBK | Back to Index page

| Prolog Control Block Contents ETHBK DSECT Storage Layout Cross Reference (Contains links to field and bit definitions) |
Programming Interface Information: This information is NOT intended to be used as Programming Interfaces of z/VM.

ETHBK Prolog | Top of page

     NAME       : HCPETHBK
     DESCRIPTION: IEEE Ethernet Frame
     DSECT      : ETHBK
     FUNCTION   :
                  The ETHBK maps the fields in an Ethernet Frame for a
                  layer 2 datagram as defined by IEEE Architecture.
     CREATED BY : Not Applicable
     DELETED BY : Not Applicable
      NCHORED   - Not Applicable
     RELOCATION CONSIDERATIONS : None
     COMMENTS   :
                  - This control block does NOT represent a CP object.
                  Instead, it maps the IEEE Ethernet Frame for a
                  layer 2 LAN data transmission.

ETHBK Control Block Content | Top of page

     ETHBK DSECT
    Top of page

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      ETHBK          IEEE Ethernet Frame
    0000    0 Bitstring    6 ETHDEST        +00 Destination MAC Address
    0006    6 Bitstring    6 ETHSRC         +06 Source MAC Address
              0000000C       ETHMACLN       *-ETHBK Length of ETHBK MAC
                                            addresses
    000C   12 Bitstring    2 ETHTYPE        +0C Type of next element
              0000000E       ETHNEXT        * +0E Next element begins here
              0000000E       ETHBKLN        *-ETHBK Length of ETHBK
          Ethernet Extension for 802.1q VLAN Tag.
    000E   14 Bitstring    2 ETHXTAG        +0E Priority||Canonical||VLANID
    0010   16 Bitstring    2 ETHXTYPE       +10 Type of next element (after
                                            TAG)
              00000004       ETHVLANB       *-ETHXTAG Length of VLAN TAG Info
              00000012       ETHXNEXT       * +12 Next element begins here
          The value of 1536 was chosen by the IETF to denote a TYPE
          to provide the ability to distinguish between Ethernet v2
          (DIX) from the 802.3 Ethernet encapsulations. The value
          1536 or higher in a LENGTH/TYPE field of an Ethernet
          classifies the field as a TYPE (Ethernet v2).
              00000600       ETHV2          1536 MIN Length/TYPE for Ethernet
                                            v2
          Generic Frame Header (starts with Ethernet type).

ETHBK Storage Layout | Top of page

    *** ETHBK - IEEE Ethernet Frame
    *
    *     +-----------------------------------------+-------------+
    *   0 |                ETHDEST                  |   (006)-    |
    *     +---------------------------+-------------+-------------+
    *   8 |         -ETHSRC           |  ETHTYPE    |  ETHXTAG    |
    *     +-------------+-------------+-------------+-------------+
    *  10 |  ETHXTYPE   | 12
    *     +-------------+
    *
    *** ETHBK - IEEE Ethernet Frame

ETHBK Cross Reference | Top of page

    Symbol         Dspl Value
    -------------- ---- -----
    ETHBKLN        000C 0000000E
    ETHDEST        0000
    ETHMACLN       0006 0000000C
    ETHNEXT        000C 0000000E
    ETHSRC         0006
    ETHTYPE        000C
    ETHVLANB       0010 00000004
    ETHV2          0010 00000600
    ETHXNEXT       0010 00000012
    ETHXTAG        000E
    ETHXTYPE       0010

This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:28:05 EDT.
Copyright IBM Corporation, 1990, 2020