MKPDU Back to Index page
 
Prolog 
Control Block Contents 
   MKPDU 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.


  MKPDU Prolog Top of page
 
 NAME       : HCPMKPDU
 DESCRIPTION: LinkAG Marker Protocol-Data-Unit (PDU)
              Control Block
 DSECT      : MKPDU
 FUNCTION   : This control block maps the IEEE 802.3ad-2000
              version 1 Marker PDU and Marker Response
              PDU structure.
              The Marker protocol allows LinkAG Logic to
              request the transmission of a Marker PDU on a
              given port.  The Marker PDU is received by the
              connected switch and a Marker Response PDU is
              returned on the same port back to our LinkAG
              logic.  When our LinkAG logic requests
              transmission of a Marker PDU on a given port
              and does not transmit any further MAC Client
              PDUs that relate to a given set of
              conversations until the corresponding Marker
              Response PDU is received from that link, then
              it can be certain that there are no MAC Client
              PDUs related to those conversations still to
              be received by the connected switch.  The use
              of the Marker protocol can therefore allow our
              LinkAG logic a means of determining the point
              at which a given set of conversations can
              safely be reallocated from one port to another
              without the danger of causing frames in those
              conversations to be misordered.
  Destination Address (DA):
    The DA in all Marker and Marker Response PDUs is the
    Slow_Protocols_Multicast address (01-80-C2-00-00-02).
  Source Address (SA):
    The SA in Marker and Marker Response PDUs is the
    individual MAC address associated with the port from
    which the PDU is transmitted.
  Length/Type:
    Marker and Marker Response PDUs are always Type
    encoded, and carry the Slow Protocol type field.  The
    encoding of this type field is 0x8809.
  Subtype:
    The Subtype field identifies the specific Slow
    Protocol being encapsulated.  Both Marker and Marker
    Response PDUs carry the Marker_subtype value 0x02
  Version number:
    This identifies the Marker protocol version;
    implementations conformant to IEEE 802.3ad of the
    standard carry the value 0x01.
  TLV_type:
    This indicates the nature of the information carried
    in this TLV-tuple.  Marker Information is encoded as
    the integer value 0x01; Marker Response Information is
    encoded as the integer value 0x02.
  Marker_Information_Length:
    This field indicates the length (in octets) of this
    TLV-tuple.  Both Marker and Marker Response
    information use a length value of 16 (0x10).
  Requester_Port:
    The port number assigned to the port by the Requester
    (the System sending the initial Marker PDU), encoded
    as an unsigned integer.
  Requester_System:
    The Requester's System ID, encoded as a MAC address.
  Requester_Transaction_ID:
    The transaction ID allocated to this request by the
    requester, encoded as an integer.
  Pad:
    This field is used to align TLV-tuples on 16-byte
    memory boundaries.  It is transmitted as zeroes in
    Marker PDUs; in Marker Response PDUs, this field may
    be transmitted as zeroes, or with the contents of this
    field from the Marker PDU triggering the response.
    The field is ignored on receipt in all cases.
  TLV_type:
    This field indicates the nature of the information
    carried in this TLV-tuple.  Terminator (end of
    message) information carries the integer value 0x00.
  Terminator_Length:
    This field indicates the length (in octets) of this
    TLV-tuple.  Terminator information uses a length value
    of 0 (0x00).
  Reserved:
    These 90 octets are reserved for use in future
    extensions to the protocol.  It is transmitted as
    zeroes in Marker PDUs; in Marker Response PDUs, this
    field may be either transmitted as zeroes, or with the
    contents of this field from the Marker PDU triggering
    the response.  The field is ignored on receipt in all
    cases.
  FCS:
    This field is the Frame Check Sequence, typically
    generated by the underlying MAC.
    VM will create the packet without the FCS, as it
    will be added/removed by OSA.
 CREATED BY - The LinkAG logic (HCPSWA), when generating
              or responding to a Marker PDU.  The DSECT
              is used to map data sent or received on
              a QDIO input or output queue.
 DELETED BY - The LinkAG logic (HCPSWA) or VSWITCH real
              OSA Port output queue handler.
 RELOCATION CONSIDERATIONS - None
 ANCHORED   - None
 
 
  MKPDU Control Block Content Top of page
 

 MKPDU DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure MKPDU LinkAG Marker Protocol-Data-Unit (PDU) Destination Address 0000 0 Bitstring 6 MKPDEST Destination Address 0MKPDEST MKPSPMAH X'0180C200' MKPSPMAH Slow-Protocol-Multicast MSB .... ..1. MKPSPMAL X'0002' MKPSPMAL LSB Bytes 0006 6 Bitstring 6 MKPSOURC Source Address 000C 12 Bitstring 4 MKPVID (0) Marker Verification Fields 000C 12 Bitstring 2 MKPLEN Length/Type Field 00MKPLEN MKPSPTF X'8809' MKPSPTF Slow-Protocol-Type Field 000E 14 Bitstring 1 MKPSTYPE Slow Protocol Type .... ..1. MKPMARK X'02' MKPMARK Marker PDU 000F 15 Bitstring 1 MKPVER Marker Protocol Version .... ...1 MKPVER1 X'01' MKPVER1 IEEE 802.3ad Version 1 0010 16 Bitstring 1 MKPTLV TLV_type Information .... ...1 MKPMINFO X'01' MKPMINFO Marker Information Encoded .... ..1. MKPRINFO X'02' MKPRINFO Marker Response Encoded 0011 17 Bitstring 1 MKPMILEN Marker Information Length ...1 .... MKPMISIZ X'10' MKPMISIZ Marker Information length 0012 18 Signed 2 MKPORT Requester's Port Number 0014 20 Bitstring 6 MKPREQID Requester's System ID 001A 26 Bitstring 4 MKPTRNID Requester's Transaction ID 001E 30 Signed 2 * Reserved for Future Use 0020 32 Signed 2 MKPTLVT TLV_type Terminator .... .... MKPTLVEN X'0000' MKPTLVEN End of TLV_type information 0022 34 Bitstring 90 * Reserved for Future Use Frame Check Sequence will be added/removed by OSA MKPFCS DS F Frame Check Sequence 007C 124 Bitstring 1 MKP$END (0) The end Notes : The following assembler equates are defined and can be used but do not appear in the control block expansion because they are in the PLX section and PRINT OFF, NOGEN are in effect.
 
 
  MKPDU Storage Layout Top of page
 
          
*** MKPDU - LinkAG Marker Protocol-Data-Unit (PDU)
*
*     +-----------------------------------------+-------------+
*   0 |                MKPDEST                  |   (006)-    |
*     +---------------------------+-------------+------+------+
*   8 |        -MKPSOURC          |   MKPLEN    |:STYPE|MKPVER|
*     +------+------+-------------+-------------+------+------+
*  10 |MKPTLV|:MILEN|   MKPORT    |        MKPREQID-          |
*     +------+------+-------------+-------------+-------------+
*  18 |   -(014)    |         MKPTRNID          |/////////////|
*     +-------------+---------------------------+-------------+
*  20 |  MKPTLVT    |/////////////////////////////////////////|
*     +-------------+/////////////////////////////////////////|
*  28 |///////////////////////////////////////////////////////|
*     =///////////////////////////////////////////////////////=
*     |///////////////////////////+---------------------------+
*     |///////////////////////////|
*     +---------------------------+
*
*** MKPDU - LinkAG Marker Protocol-Data-Unit (PDU)
 
 
  MKPDU Cross Reference Top of page
 
 
Symbol         Dspl Value
-------------- ---- -----
MKP$END        007C
MKPDEST        0000
MKPLEN         000C
MKPMARK        000E 02
MKPMILEN       0011
MKPMINFO       0010 01
MKPMISIZ       0011 10
MKPORT         0012
MKPREQID       0014
MKPRINFO       0010 02
MKPSOURC       0006
MKPSPMAH       0000 0MKPDEST
MKPSPMAL       0000 02
MKPSPTF        000C 00MKPLEN
MKPSTYPE       000E
MKPTLV         0010
MKPTLVEN       0020 00
MKPTLVT        0020
MKPTRNID       001A
MKPVER         000F
MKPVER1        000F 01
MKPVID         000C
 
This information is based on z/VM 7.3.0 Last updated on 22 Jun 2022 at 15:52:45 EDT.
Copyright IBM Corporation, 1990, 2022