IP4HDR Back to Index page
 
Prolog 
Control Block Contents 
   IP4HDR 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.

 
  IP4HDR Control Block Content Top of page
  




 IP4HDR DSECT
Top of page


Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      IP4HDR         IP (Internet Protocol) Header
      IP Header for IPv4 (ETHTYPE = x'0800').
0000    0 Bitstring    1 IP4VER         +00 IP Version || header length
          00000045       IP4VHDRL       X'45' IP4VHDRL - IPv4 and header
                                        length of 5
0001    1 Bitstring    1 IP4TOS         +01 Type of service
0002    2 Bitstring    2 IP4TOTLN       +02 Total Length
0004    4 Bitstring    2 IP4ID          +04 Identification
0006    6 Signed       2 IP4FIELD (0)   Flags (3 bits || Frag 13 bits)
0006    6 Bitstring    1 IP4FLAGS       +06 Flags (Bits 0,1,2)
          00000040       IP4DF          X'40' IP4DF - Pv4 "Don't Fragment
                                        Flag
0007    7 Bitstring    1 *              +07 Fragment offset (partial)
0008    8 Bitstring    1 IP4TTL         +08 TTL Counter
0009    9 Bitstring    1 IP4PROT        +09 Protocol
          00000001       IP4ICMP        1 IP4ICMP - ICMP
          00000002       IP4IGMP        2 IP4IGMP - IGMP
          00000006       IP4TCP         6 IP4TCP - TCP
          00000011       IP4UDP         17 IP4UDP - UDP
000A   10 Bitstring    2 IP4CKSUM       +0A IP Header only Checksum
000C   12 Bitstring    4 IP4SRC         +0C IPv4 Source Address
0010   16 Bitstring    4 IP4DEST        +10 IPv4 Destination Address
          00000014       IP4NEXT        * +14 Start of next element
          00000014       IP4LENTH       *-IP4HDR Length of IPv4 header in
                                        bytes
          00000007       IP4ICPWD       (IP4LENTH+8)/4 IPv4 ICMP payload
                                        in words
          0000001C       IP4ICPBT       (IP4LENTH+8) IPv4 ICMP payload in
                                        bytes
      IPv6 - Internet Protocol Header
 
 
  IP4HDR Storage Layout Top of page
  
          
*** IP4HDR - IP (Internet Protocol) Header
*
*     +------+------+-------------+-------------+------+------+
*   0 |IP4VER|IP4TOS|  IP4TOTLN   |   IP4ID     |:FLAGS|//////|
*     +------+------+-------------+-------------+------+------+
*   8 |IP4TTL|:PROT |  IP4CKSUM   |          IP4SRC           |
*     +------+------+-------------+---------------------------+
*  10 |         IP4DEST           | 14
*     +---------------------------+
*
*** IP4HDR - IP (Internet Protocol) Header
 
 
  IP4HDR Cross Reference Top of page
  
 
Symbol         Dspl Value
-------------- ---- -----
IP4CKSUM       000A
IP4DEST        0010
IP4DF          0006 00000040
IP4FIELD       0006
IP4FLAGS       0006
IP4ICMP        0009 00000001
IP4ICPBT       0010 0000001C
IP4ICPWD       0010 00000007
IP4ID          0004
IP4IGMP        0009 00000002
IP4LENTH       0010 00000014
IP4NEXT        0010 00000014
IP4PROT        0009
IP4SRC         000C
IP4TCP         0009 00000006
IP4TOS         0001
IP4TOTLN       0002
IP4TTL         0008
IP4UDP         0009 00000011
IP4VER         0000
IP4VHDRL       0000 00000045
 
This information is based on z/VM 7.3.0 Last updated on 22 Jun 2022 at 15:51:36 EDT.
Copyright IBM Corporation, 1990, 2022