Initializing a TCP stack for use with both IPv4 and IPv6 addresses

To use both IPv4 and IPv6 addresses, Db2 requires TCP/IP dual-mode stack support. Dual-mode stack support allows IPv4 address communication with IPv4 partners, and IPv6 address communication with IPv6 partners.

About this task

If you need only IPv4 address communication, an IPv4-only stack environment is sufficient because Db2 detects if the stack supports IPv6, and if not, Db2 allows communication with IPv4 addresses only.

Procedure

To enable TCP/IP for IPv4/IPv6 dual-mode stack:

Modify the BPXPRMxx member to define two NETWORK statements, one for AF_INET, and another for AF_INET6.

The following example shows two NETWORK statements in the BPXPRMxx member:

FILESYSTYPE TYPE(INET) ENTRYPOINT(EZBPFINI)
NETWORK DOMAINNAME(AF_INET)
        DOMAINNUMBER(2)
        MAXSOCKETS(12000)
        TYPE(INET)
NETWORK DOMAINNAME(AF_INET6)
        DOMAINNUMBER(19)
        MAXSOCKETS(13000)
        TYPE(INET)
SUBFILESYSTYPE NAME(TCPIP) ENTRYPOINT(EZBPFINI)
        TYPE(INET)

Separate MAXSOCKETS values are supported. The IPv6 default will be the IPv4 specified value.

To verify that TCP/IP is configured to support a dual-mode environment, enter a d tcpip,,netstat,home command on the z/OS® console. Look for the INTFNAME field that has a value of LOOPBACK6 and verify that the associated ADDRESS field has a compressed colon-hexadecimal IPv6 address of ::1.
The following example shows that TCP/IP is configured to support both IPv4 and IPv6:
```
d tcpip,,netstat,home
  EZD0101I NETSTAT CS V1R5 TCPIP 034
  HOME ADDRESS LIST:
  LINKNAME: CTC1LINK
    ADDRESS: 9.30.115.135
      FLAGS: PRIMARY
  LINKNAME: LOOPBACK
    ADDRESS: 127.0.0.1
      FLAGS:
  INTFNAME: LOOPBACK6
    ADDRESS: ::1
      TYPE: LOOPBACK
      FLAGS:
  3 OF 3 RECORDS DISPLAYED
```