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 7.3.0 Last updated on 22 Jun 2022 at 15:50:18 EDT.
Copyright IBM Corporation, 1990, 2022