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 7.2.0 Last updated on 24 Jun 2020 at 09:28:39 EDT.
Copyright IBM Corporation, 1990, 2020