Configuring the policy table for default address selection
You can configure the policy table for default address selection to better suit your environment by using the DEFADDRTABLE statement.
Before you begin
Perform the following steps to configure the policy table for default address selection:
- Take one of the following actions, depending on how you
want to configure the table:
- To configure a new policy table for IPv6 default address selection, add a DEFADDRTABLE block to your TCP/IP profile that contains the appropriate policy entries.
- To change the policy table that is currently being used for IPv6 default address selection, create a DEFADDRTABLE block that contains the existing set of policies (default or configured policies) and update the policy entries that you want to change.
- To remove all policies that are currently configured and revert
to the default entries, create a DEFADDRTABLE block that does not
contain any policies:
- Issue the VARY TCPIP,,OBEYFILE command to replace the existing or default policy entries and to activate the configuration changes.
To prefer IPv4 addresses over IPv6 addresses, you can change the precedence of the ::ffff:0.0.0.0/96 prefix to 100. This precedence value gives the IPv4-mapped IPv6 prefix (::ffff:0.0.0.0/96) a higher precedence than all IPv6 prefixes.
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
To sort global destinations before link-local destinations, you can add an entry to the table for the fe80::/10 prefix. This entry gives link-local destinations (which match the fe80::/10 prefix) a lower precedence than all global addresses (which match the ::/0 prefix).
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
For information about the DEFADDRTABLE statement, see z/OS Communications Server: IP Configuration Reference.