Defining at least one static VIPA is required by VTAM® to access the IP network. Because VTAM does not move within a sysplex,
a dynamic VIPA cannot be used. Enterprise Extender supports the use
of multiple static VIPA addresses, and a VIPA address is chosen as
follows:
- VTAM uses the IPADDR value
specified on the Enterprise Extender XCA major node GROUP definition
statement, or the VIPA address obtained when name-to-address resolution
is performed on the HOSTNAME value specified on the Enterprise Extender
XCA major node GROUP definition statement.
- If the GROUP definition statement specifies neither IPADDR nor
HOSTNAME, VTAM uses the static
VIPA address specified on the VTAM IPADDR
start option, or the static VIPA address returned by the resolver
when name-to-address resolution is performed on the value of the VTAM HOSTNAME start option.
- If neither the IPADDR nor the HOSTNAME start option is specified, VTAM uses the first IPv4 static
VIPA in the HOME list.
If remote APPN nodes use a host name and not a host address to
define the destination of an Enterprise Extender connection, the domain
name server must return the VIPA address used by VTAM for the host name. Alternatively, if the
Enterprise Extender endpoints are behind a firewall or for another
reason require network address translation, the domain name server
should return a network address translation (NAT) address. This NAT
address should in turn map, on the destination side, to the static
VIPA address of the intended target VTAM host.
Rule: If you plan on using IPv4 protocols
for your Enterprise Extender communication, you must define DEVICE,
LINK, and optionally HOME statements for IUTSAMEH, or specify IPCONFIG
DYNAMICXCF in the appropriate TCPIP profile data set. If you plan
on using IPv6 protocols for your Enterprise Extender communication,
you must define an INTERFACE statement for IUTSAMEH or specify IPCONFIG6
DYNAMICXCF in the appropriate TCPIP profile data set.
For more information about using Enterprise Extender, see z/OS Communications Server: SNA Network Implementation
Guide.