A virtual IP address (VIPA) is an internet address on a z/OS® host that is not associated
with a physical adapter. A VIPA removes the adapter as a single point
of failure by providing an IP address that is associated with a stack
without associating it with a specific physical network attachment.
Procedure
Perform the following steps to configure a static VIPA
address in one stack:
- When configuring static VIPAs for the IPv4 network, add an INTERFACE statement of type VIRTUAL for each static VIPA to
be defined. Alternatively, add DEVICE, LINK, HOME, and optionally
BSDROUTINGPARMS statements for each static VIPA to be defined. When
configuring static VIPAs for the IPv6 network, add INTERFACE statements
of type VIRTUAL6 for each static VIPA to be defined.
Notes: - A VIPA link or VIPA interface cannot be coded on a static route
in the BEGINROUTES statement.
- If you want to add a static VIPA in an IPv4 network with an address
that already exists in the HOME list, you must first delete the existing
address using the VARY TCPIP,,OBEYFILE command with the existing address
omitted from the HOME list. Then use the VARY TCPIP,,OBEYFILE command
with a new and complete HOME list.
- For IPv4 networks, if tolerance of device and adapter failures
is wanted for connection requests that originate at a z/OS TCP/IP stack, specify the SOURCEVIPA option
on the IPCONFIG statement.
Tips: - For the SOURCEVIPA option to work properly, the receiving nodes
in the network must be configured to recognize the SOURCEVIPA addresses
using the static or dynamic routing protocols. Otherwise, timeouts
for the connection or request responses will occur as a result of
the VIPA addresses being network unreachable.
- If TCPSTACKSOURCEVIPA
is specified on the IPCONFIG statement, it overrides SOURCEVIPA for
outbound IPv4 TCP connections. If the SRCIP profile statement block
is defined to establish one or more job-specific or destination-specific
source IPv4 addresses, these IP addresses override TCPSTACKSOURCEVIPA
or the VIPAs in the HOME list for IPCONFIG SOURCEVIPA, or both, for
the specified job names and destinations. For information about the
hierarchy of various ways that the source IP address of an outbound
connection is determined, see Source IP address selection.
For more information on configuring IPv4 SOURCEVIPA
or TCPSTACKSOURCEVIPA addresses on the IPCONFIG statement, or SRCIP addresses in the SRCIP statement block, see z/OS Communications Server: IP Configuration Reference.
- For IPv6 networks, if tolerance of device and adapter failures
is wanted for connection requests that originate at a z/OS TCP/IP stack, specify the following option
or keyword:
- The SOURCEVIPA option on the IPCONFIG6 statement.
- The SOURCEVIPAINT keyword with a VIPA interface name on the INTERFACE
statements of the real (physical) interfaces, or on the DYNAMICXCF
specification on the IPCONFIG6 statement.
Tips: - For the SOURCEVIPA option to work properly, the receiving nodes
in the network must be configured to recognize the SOURCEVIPAINT addresses
using the static or dynamic routing protocols. Otherwise, timeouts
for the connection or request responses will occur as a result of
the VIPA addresses being network unreachable.
- If the TCPSTACKSOURCEVIPA parameter is specified on the IPCONFIG6
statement, it overrides the SOURCEVIPA value for outbound IPv6 TCP
connections. If the SRCIP profile statement block is defined to establish
one or more job-specific or destination-specific source IPv6 addresses,
these IP addresses override the TCPSTACKSOURCEVIPA value, the SOURCEVIPAINT
value, or both, for the specified job names and destinations. For
information about the hierarchy of various ways that the source IP
address of an outbound connection is determined, see Source IP address selection.
For more information on configuring IPv6 SOURCEVIPA
or TCPSTACKSOURCEVIPA addresses on the IPCONFIG6 statement, or SRCIP addresses in
the SRCIP statement block, see z/OS Communications Server: IP Configuration Reference.
- For host name resolution of a VIPA address, configure the
domain name servers to associate the host name with the VIPA.
- Configure the routing daemon to advertise the presence
of the VIPA. As described in prior steps, remember that
the VIPA to be advertised can be determined by the SOURCEVIPA or TCPSTACKSOURCEVIPA
parameters on the IPCONFIG and IPCONFIG6 statements, or by the SRCIP statement. For more information, see z/OS Communications Server: IP Configuration Reference.
Results
Figure 1 illustrates a simple
configuration showing multiple network attachments using a single
static VIPA address. Because any other network interface can be used
with static VIPA's, see Setting up physical characteristics in PROFILE.TCPIP for
descriptions of other network interfaces. The simple configuration
will be used as the TCPCS6 system throughout this information.
Figure 1. Static VIPA configuration
