IBM AIX HACMP, Hardware User Manual

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IBM Certification Study Guide AIX HACMP
service label (address) instead of the boot label. If the
node should fail, a takeover node acquires the failed
node’s service address on its standby adapter, thus
making the failure transparent to clients using that specific
service address.
During the reintegration of the failed node, which comes
up on its boot address, the takeover node will release the
service address it acquired from the failed node.
Afterwards, the reintegrating node will reconfigure its
adapter from the boot address to its reacquired service
address.
Consider the following scenario: Suppose that Node A
fails. Node B acquires Node A’s service address and
services client requests directed to that address. Later,
when Node A is restarted, it comes up on its boot address
and attempts to reintegrate into the cluster on its service
address by requesting that Node B release Node A’s
service address. When Node B releases the requested
address, Node A reclaims the address and reintegrates it
into the cluster. Reintegration, however, fails if Node A has
not been configured to boot using its boot address.
The boot address does not use a separate physical
adapter, but instead is a second name and IP address
associated with a service adapter. It must be on the same
subnetwork as the service adapter. All cluster nodes must
have this entry in the local /etc/hosts
file and, if
applicable, in the nameserver configuration.
2.4.3.4 Defining Hardware Addresses
The hardware address swapping facility works in tandem with IP address
takeover. Hardware address swapping maintains the binding between an IP
address and a hardware address, which eliminates the need to flush the ARP
cache of clients after an IP address takeover. This facility, however, is
supported only for Ethernet, Token-Ring, and FDDI adapters. It does not work
with the SP Switch or ATM LAN emulation networks.
Note that hardware address swapping takes about 60 seconds on a
Token-Ring network, and up to 120 seconds on an FDDI network. These
periods are longer than the usual time it takes for the Cluster Manager to
detect a failure and take action.