Prefix Precedence Label
::1/128 50 0
::/0 40 1
2002::/16 30 2
::/96 20 3
::ffff:0.0.0.0/96 10 4
Restriction: Only one DEFADDRTABLE block should appear in a configuration data set. Any subsequent DEFADDRTABLE blocks are ignored, and an informational message is displayed. If a syntax error is encountered when this statement is processed, an error message is displayed, and the entire DEFADDRTABLE block is ignored (no entries are processed).
Guideline: The order of the entries in the policy table is not important. When the policy table is used during address selection, all entries in the table are searched to locate the entry with the prefix that best matches (longest prefix match) the address for which precedence and label values are needed.
For more information about the policy table for default address selection and the precedence and label values, see z/OS Communications Server: IPv6 Network and Application Design Guide.
.------------------. V | >>-DEFADDRTable----| Policy Entry |-+--ENDDEFADDRTable--------->< Policy Entry .-----------------------------------------. V | |----prefix/prefix_length--precedence--label-+------------------|
If duplicate prefix entries are specified in the same DEFADDRTABLE block, the first prefix entry is used, the remaining duplicate prefix entries are ignored, and messages are displayed.
An integer value in the range 0 - 65530 that specifies the precedence that is used to sort destination addresses.
The following considerations apply when you modify the DEFADDRTABLE block:
DEFADDRTABLE ENDDEFADDRTABLE
Issue
the VARY TCPIP,,OBEYFILE command; the default policy table replaces
the previously configured values.The default policy table contains the following values:
DEFADDRTABLE
; Prefix Precedence Label
::1/128 50 0
::/0 40 1
2002::/16 30 2
::/96 20 3
::ffff:0.0.0.0/96 10 4
ENDDEFADDRTABLE
This default table specifies the following behavior:
Guideline: IPv4-compatible addresses have been deprecated by RFC 4291, but are shown here because they are part of the default policy table defined by RFC 3484.
To specify that IPv4 network transport should be preferred over IPv6 network transport, change the precedence of the ::ffff:0.0.0.0/96 prefix to 100.
DEFADDRTABLE
; Prefix Precedence Label
::1/128 50 0
::/0 40 1
2002::/16 30 2
::/96 20 3
::ffff:0.0.0.0/96 100 4
ENDDEFADDRTABLE
All other considerations being equal, a destination address whose label does not match the label of any of the possible source addresses prefers an IPv4 source address because the precedence value for the ::ffff:0.0.0.0/96 prefix is higher than the precedence value of all the other entries.
The destination address selection rules give preference to destinations of smaller scope. For example, a link-local destination is sorted before a global scope destination when the two are otherwise equally suitable. To sort global destinations before link-local destinations, change the policy table to reverse the existing preference.
DEFADDRTABLE
; Prefix Precedence Label
::1/128 50 0
::/0 40 1
fe80::/10 33 1
2002::/16 30 2
::/96 20 3
::ffff:0.0.0.0/96 100 4
ENDDEFADDRTABLE