You do not need to configure a private network for a single-host global cluster. The scinstall utility automatically assigns the default private-network address and netmask, even though a private network is not used by the cluster.
Sun Cluster software uses the private network for internal communication among nodes and among non-global zones that are managed by Sun Cluster software. A Sun Cluster configuration requires at least two connections to the cluster interconnect on the private network. When you configure Sun Cluster software on the first node of the cluster, you specify the private-network address and netmask in one of the following ways:
Accept the default private-network address (172.16.0.0) and default netmask.
On the Solaris 10 OS, the default netmask is 255.255.240.0. This IP address range supports a combined maximum of 64 voting nodes and non-global zones, a maximum of 12 zone clusters, and a maximum of 10 private networks.
On the Solaris 9 OS, the default netmask is 255.255.248.0. This IP address range supports a combined maximum of 64 nodes and a maximum of 10 private networks.
The maximum number of voting nodes that an IP address range can support does not reflect the maximum number of voting nodes that the hardware or software configuration can currently support.
Specify a different allowable private-network address and accept the default netmask.
Accept the default private-network address and specify a different netmask.
Specify both a different private-network address and a different netmask.
If you choose to specify a different netmask, the scinstall utility prompts you for the number of nodes and the number of private networks that you want the IP address range to support. On the Solaris 10 OS, the utility also prompts you for the number of zone clusters that you want to support. The number of global-cluster nodes that you specify should also include the expected number of unclustered non-global zones that will use the private network.
The utility calculates the netmask for the minimum IP address range that will support the number of nodes, zone clusters, and private networks that you specified. The calculated netmask might support more than the supplied number of nodes, including non-global zones, zone clusters, and private networks. The scinstall utility also calculates a second netmask that would be the minimum to support twice the number of nodes, zone clusters, and private networks. This second netmask would enable the cluster to accommodate future growth without the need to reconfigure the IP address range.
The utility then asks you what netmask to choose. You can specify either of the calculated netmasks or provide a different one. The netmask that you specify must minimally support the number of nodes and private networks that you specified to the utility.
Changing the cluster private IP-address range might be necessary to support the addition of voting nodes, non-global zones, zone clusters, or private networks.
To change the private-network address and netmask after the cluster is established, see How to Change the Private Network Address or Address Range of an Existing Cluster in Sun Cluster System Administration Guide for Solaris OS. You must bring down the cluster to make these changes.
However, on the Solaris 10 OS the cluster can remain in cluster mode if you use the cluster set-netprops command to change only the netmask. For any zone cluster that is already configured in the cluster, the private IP subnets and the corresponding private IP addresses that are allocated for that zone cluster will also be updated.
If you specify a private-network address other than the default, the address must meet the following requirements:
Address and netmask sizes – The private network address cannot be smaller than the netmask. For example, you can use a private network address of 172.16.10.0 with a netmask of 255.255.255.0. But you cannot use a private network address of 172.16.10.0 with a netmask of 255.255.0.0.
Acceptable addresses – The address must be included in the block of addresses that RFC 1918 reserves for use in private networks. You can contact the InterNIC to obtain copies of RFCs or view RFCs online at http://www.rfcs.org.
Use in multiple clusters – You can use the same private-network address in more than one cluster, provided that the clusters are on different private networks. Private IP network addresses are not accessible from outside the physical cluster.
For Sun Logical Domains (LDoms) guest domains that are created on the same physical machine and that are connected to the same virtual switch, the private network is shared by such guest domains and is visible to all these domains. Proceed with caution before you specify a private-network IP address range to the scinstall utility for use by a cluster of guest domains. Ensure that the address range is not already in use by another guest domain that exists on the same physical machine and shares its virtual switch.
IPv6 – Sun Cluster software does not support IPv6 addresses for the private interconnect. The system does configure IPv6 addresses on the private-network adapters to support scalable services that use IPv6 addresses. But internode communication on the private network does not use these IPv6 addresses.