FRMHDR | Back to Index page

| Prolog Control Block Contents FRMHDR 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.

FRMHDR Control Block Content | Top of page

     FRMHDR DSECT
    Top of page

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      FRMHDR         IEEE Ethernet Frame
    0000    0 Bitstring    2 FRMTYPE        Ethernet Type
              00000002       FRMDATA        * Frame data
          VLAN Tag Control Frame (ETHTYPE = x8100)
              00000002       VLANCTL        * Beginning of IEEE VLAN Tag
    0002    2 Bitstring    2 VLANTAG        +00 Priority||Canonical||VLANID
          Masks defined for VLANTAG
              0000E000       VLANPRMK       X'E000' Mask on VLANTAG Priority
                                            bits
              00001000       VLANCNMK       X'1000' Mask on VLANTAG Canonical
                                            bit
              00000FFF       VLANIDMK       X'0FFF' Mask on VLANTAG VLAN ID
                                            bits
    0004    4 Bitstring    2 VLANTYPE       +02 Type of next element
              00000006       VLANNEXT       * +04 Next element begins here
              00000004       VLANCTLN       *-VLANCTL Length of VLANCTL
          Ethernet 802.3 LLC Header (FRMTYPE <= 1500)
    0000    0 Bitstring    2 FRMETHLN       +00 FRMTYPE == 802.3 Data Length
    0002    2 Bitstring    3 FRMLLC (0)     +02 LLC fields (DSAP||SSAP||CNTL)
    0002    2 Bitstring    1 FRMDSAP        +02 DSAP
    0003    3 Bitstring    1 FRMSSAP        +03 SSAP
    0004    4 Bitstring    1 FRMCNTL        +04 Control
              00000005       LLCDATA        * LLC Frame Data begins here
    0005    5 Bitstring    3 SNAPOUI        +05 Organizational Unique
                                            Identifier
    0008    8 Bitstring    2 SNAPTYPE       +08 Ethernet Frame Type in SNAP
                                            HDR
              0000000A       SNAPDATA       * +0A Data following SNAP header
          ARP Frame (FRMTYPE = x'0806')
              00000002       ARPFRAME       * Beginning of ARP frame header
    0002    2 Bitstring    2 ARPHWTYP       +00 Hardware Type (Ethernet=0001)
    0004    4 Bitstring    2 ARPPRTYP       +02 Protocol Type (IP=0800)
    0006    6 Bitstring    1 ARPHWLEN       +04 Hardware Address Length (06)
    0007    7 Bitstring    1 ARPPRLEN       +05 Protocol Address Length (04)
    0008    8 Bitstring    2 ARPFUNC        +06 ARP function code
              .... ...1      ARPRQ          X'0001' ARPRQ - ARP Request
                                            function
              .... ..1.      ARPRP          X'0002' ARPRP - ARP Reply
                                            function
    000A   10 Bitstring    6 ARPHWSRC       +08 Hardware Source Address (MAC)
    0010   16 Bitstring    4 ARPPRSRC       +0E IPv4 Source Address
    0014   20 Bitstring    6 ARPHWTRG       +12 Hardware Target Address (MAC)
    001A   26 Bitstring    4 ARPPRTRG       +18 IPv4 Target Address
              0000001C       ARPFRMLN       *-ARPFRAME Length of ARP frame

FRMHDR Storage Layout | Top of page

    *** FRMHDR - IEEE Ethernet Frame
    *
    *     +-------------+
    *   0 |  FRMTYPE    | 2
    *     +-------------+
    *
    *** FRMHDR - IEEE Ethernet Frame

    *** Overlay for FRMDATA in FRMHDR
    *
    *                   +-------------+-------------+
    *   0 ...         2 |  VLANTAG    |  VLANTYPE   | 6
    *                   +-------------+-------------+
    *
    *** Overlay for FRMDATA in FRMHDR

    *** Overlay for FRMHDR in FRMHDR
    *
    *     +-------------+------+------+------+--------------------+
    *   0 |  FRMETHLN   |:DSAP |:SSAP |:CNTL |      SNAPOUI       |
    *     +-------------+------+------+------+--------------------+
    *   8 |  SNAPTYPE   | A
    *     +-------------+
    *
    *** Overlay for FRMHDR in FRMHDR

    *** Overlay for FRMDATA in FRMHDR
    *
    *                   +-------------+-------------+------+------+
    *   0 ...         2 |  ARPHWTYP   |  ARPPRTYP   |:HWLEN|:PRLEN|
    *     +-------------+-------------+-------------+------+------+
    *   8 |  ARPFUNC    |                ARPHWSRC                 |
    *     +-------------+-------------+---------------------------+
    *  10 |         ARPPRSRC          |        ARPHWTRG-          |
    *     +-------------+-------------+-------------+-------------+
    *  18 |   -(014)    |         ARPPRTRG          | 1E
    *     +-------------+---------------------------+
    *
    *** Overlay for FRMDATA in FRMHDR

FRMHDR Cross Reference | Top of page

    Symbol         Dspl Value
    -------------- ---- -----
    ARPFRAME       0008 00000002
    ARPFRMLN       001A 0000001C
    ARPFUNC        0008
    ARPHWLEN       0006
    ARPHWSRC       000A
    ARPHWTRG       0014
    ARPHWTYP       0002
    ARPPRLEN       0007
    ARPPRSRC       0010
    ARPPRTRG       001A
    ARPPRTYP       0004
    ARPRP          0008 02
    ARPRQ          0008 01
    FRMCNTL        0004
    FRMDATA        0000 00000002
    FRMDSAP        0002
    FRMETHLN       0000
    FRMLLC         0002
    FRMSSAP        0003
    FRMTYPE        0000
    LLCDATA        0004 00000005
    SNAPDATA       0008 0000000A
    SNAPOUI        0005
    SNAPTYPE       0008
    VLANCNMK       0002 00001000
    VLANCTL        0000 00000002
    VLANCTLN       0004 00000004
    VLANIDMK       0002 00000FFF
    VLANNEXT       0004 00000006
    VLANPRMK       0002 0000E000
    VLANTAG        0002
    VLANTYPE       0004

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