network definition from HACMP.
To remove a network from the HACMP cluster definition:
1. Enter smit hacmp
2. In SMIT, select Extended Configuration > Extended Topology Configuration >
Configure HACMP Networks > Remove a Network from the HACMP Cluster and
press Enter.
SMIT displays the Select a Network to Remove panel.
3. Select the network to remove.
SMIT displays Are you sure?
4. Press Enter to remove the network. All of this network’s subnets and their interfaces are
removed from the HACMP configuration.
5. On the same node, synchronize the cluster configuration.
If the Cluster Manager is running on the local node, the synchronization triggers a dynamic
reconfiguration event. See Synchronizing the Cluster Configuration for more
information.
Converting an HACMP Network to use IP Aliasing
If you want to change the cluster network configuration to use IPAT via Aliases instead of the
previous IPAT via IP Replacement scheme for a specific network in the cluster, you should stop
the cluster services on all nodes to make the change. This change is not allowed during a
dynamic reconfiguration (DARE) of cluster resources.
Note: If you have an SP Switch network that has been configured in your
cluster in HACMP prior to version 5.1, and want to convert the SP
Switch to use the IP aliasing in HACMP, see the section Converting
an SP Switch Network to an Aliased Network.
To convert an HACMP network to use IP Aliasing:
1. Stop the cluster services on all cluster nodes.
2. Verify that no HACMP interfaces are defined with HWAT on that network.
3. Verify that the network is configured to support gratuitous ARP in HACMP, by checking
the Extended Configuration > Extended Topology Configuration > Configure an
HACMP Network Module > Show a Network Module SMIT panel for the Gratuitous
ARP setting for that network type.
Network Type Valid types are RS232, tmssa, tmscsi, diskhb.
Managing the Cluster Topology
Changing the Configuration of an HACMP Network
Administration Guide 399
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4. To change the cluster network to use IPAT via IP Aliases instead of IPAT via IP
Replacement, see the steps in this chapter in the section Changing Network Attributes.
5. Verify and synchronize the cluster.
6. Restart the cluster services.
For more information on IPAT via IP Aliases see the relevant chapters in the Concepts and
Facilities Guide and in the Planning Guide.
Establishing Default and Static Routes on Aliased Networks
If you are setting up or converting to an IP aliased network and require establishing the default
route, and possibly, other static routes that have to be established on the IP aliased service
subnet, these routes will fail to be established automatically when the rc.net file runs at boot
time. This is because there is no address on that subnet in the Configuration Database.
To ensure that these routes are established at boot time, we recommend that you also configure
a persistent address on that subnet. After configuring the persistent address, HACMP
configures the routes.
If you do not configure persistent addresses, then you should use your own scripts that will
configure routes on aliased service subnets. For more information on the rc.net file see Chapter
1: Administering an HACMP Cluster and Chapter 9: Starting and Stopping Cluster
Services.
Converting an SP Switch Network to an Aliased Network
When you migrate your cluster to HACMP 5.4 from a version prior to HACMP 5.1, your
previously configured SP Switch network configuration remains valid. However, after
migration, HACMP by default treats your network as non-aliased, although in reality it
functions as an aliased network. Therefore, you may consider reconfiguring the existing SP
Switch network configuration.
To change the cluster configuration to use IPAT via IP Aliases instead of the standard IPAT via
IP Replacement scheme for the SP Switch network, stop the cluster services on all nodes and
make the following changes to the communication interface definitions. Such changes are not
allowed during a dynamic reconfiguration (DARE) of cluster resources.
To convert the SP Switch network to an aliased network, perform the following steps on all
cluster nodes:
1. Stop the cluster services.
2. Enter smit hacmp
3. In SMIT, select Extended Configuration > Extended Topology Configuration >
Configure HACMP Communication Interfaces/Devices > Remove Communication
Interfaces/Devices and press Enter.
4. Remove the non-service interfaces on the SP Switch network.
5. Remove the boot label that you had previously configured within HACMP for your SP
switch network.
Managing the Cluster Topology
Changing the Configuration of an HACMP Network
400 Administration Guide
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6. Go back to the Extended HACMP Verification and Synchronization option and
synchronize the cluster. If the cluster network meets all the requirements of an aliased
network, the following message appears: “Setting attribute for network
7. In SMIT, select the Extended Configuration > Extended Topology Configuration >
Configure HACMP Communication Interfaces/Devices and configure the base
interface address on the SP Switch network as a boot IP label/address in HACMP.
8. Put the service IP-based communication interface on a different subnet than the boot
interface to avoid errors during the verification process. If you have multiple service
addresses they should all be on a different subnet than the boot interface.
9. Verify that HWAT is disabled for all communication interfaces on this network.
10. Verify that the network is configured to support gratuitous ARP in HACMP, by checking
the Gratuitous ARP setting for that network type. See instructions in the section Changing
the Tuning Parameters to Custom Values.
11. In the Change/Show a Network in the HACMP Cluster SMIT panel, set the Enable IP
Address Takeover via IP Aliases field to Yes for this network.
12. Synchronize the cluster. HACMP verifies the configuration.
13. Restart the cluster services.
For more information on the SP Switch considerations, see Chapter 3: Planning Cluster
Network Connectivity in the Planning Guide.
For more information on IPAT via IP Aliases see Concepts and Facilities and Chapter 3 in the
Planning Guide.
Disabling IPAT via IP Aliases
If the network supports gratuitous ARP, you can configure the network in the HACMP cluster
to use IPAT via IP Aliases during fallover.
There are subtle differences between the operation of a network using IP aliasing and one that
does not. If you need to troubleshoot problems with external network equipment, clients, or
applications, you may want to disable IPAT via IP Aliases on the network and use IPAT via IP
Replacement instead.
To disable IPAT via IP Aliases facility for the entire network type:
1. In the SMIT Change/Show a Network in the HACMP Cluster panel, set the Enable IP
Address Takeover via IP Aliases field to No for this network.
2. Change the service IP labels to be on different subnets.
3. Press Enter to accept the changes.
4. Synchronize the cluster configuration.
Controlling Distribution Preferences for Service IP Label Aliases
To control the placement of the service IP label aliases on the cluster node physical network
interface cards, you can configure a distribution preference for the aliases of the service IP
labels that are placed under HACMP control.
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