If the DVIPA is an IPv6 DVIPA, or is an IPv4 DVIPA that was originally
configured with MOVEABLE IMMEDIATE, the following events occur:
- The DVIPA ownership is immediately transferred to the restarting
stack which adds the DVIPA to its HOME list and the routers are dynamically
notified. The restarted stack receives all new connections for that
DVIPA. The stack also can receive packets for existing connections,
and it routes these to the backup stack to preserve those connections.
- At the same time, the backup stack notifies the routers that it
no longer is the owner of the DVIPA.
- If there are no current connections to the DVIPA, it is removed
from the HOME list on the backup stack and it reverts to backup status.
- If there are any existing connections, the DVIPA remains in the
HOME list of the backup stack and the DVIPA is put into Moving status
until the last existing connection is terminated. At that time, the
DVIPA is removed from the HOME list and reverts to backup status.
IBM® recommends this form
of a planned DVIPA takeback occur only during low periods of connection
activity. This gives the attached routers time to update their routing
tables and avoid connections being reset due to receiving an ICMP_HOST_UNREACH
or ICMP6_DST_UNREACH from the router.
Tip: If OMPROUTE is used, it is recommended that GLOBALCONFIG
SYSPLEXMONITOR DELAYJOIN be configured. This causes DVIPA takeback
to be delayed until OMPROUTE is active and able to advertise DVIPAs
on the takeback stack. For more information on using DELAYJOIN, see
Sysplex problem detection and recovery.
Notes: - To ensure preservation of existing connections on the prior owning
stack, you must define DYNAMICXCF on both stacks, on the IPCONFIG
statement for IPv4 dynamic VIPAs or on the IPCONFIG6 statement for
IPv6 dynamic VIPAs.
- MOVEABLE IMMEDIATE is the default for IPv4 DVIPAs, and the only
behavior for IPv6 DVIPAs.