Use any type of communications media in your clustering environment as long as it supports Internet Protocol (IP).
Cluster resource services uses only TCP/IP protocols to communicate between nodes. Local area networks (LANs), wide area networks (WANs), OptiConnect system area networks (SANs), or any combination of these connectivity devices are supported. Your choice should be based on the following factors:
You can use these same considerations when determining the connection media to be used to connect primary and backup locations of resources. When planning your cluster, it is recommended that you designate one or more of your backup nodes in remote locations in order to survive a site loss disaster.
To avoid performance problems that might be caused by inadequate capacity, you need to evaluate the communication media that is used to handle the volumes of information that is sent from node to node. You can choose which physical media you prefer to use such as token ring, Ethernet, asynchronous transfer mode (ATM), SPD OptiConnect, High-Speed Link (HSL) OptiConnect, or Virtual OptiConnect (a high-speed internal connection between logical partitions).
HSL OptiConnect is a technology provided by OptiConnect for i5/OS™ software (i5/OS Option 23 - i5/OS OptiConnect). It can be used to construct highly available solutions. HSL OptiConnect is a system area network that provides high-speed, point-to-point connectivity between cluster nodes by using High Speed Link (HSL) Loop technology. HSL OptiConnect requires standard HSL cables, but no additional hardware.
For switchable hardware, also referred to as resilient device CRGs, you need to have an independent disk pool that is switchable in your environment. In a logical partition environment, this is a collection of disk units that are on the bus that is being shared by the logical partitions, or that are attached to an input/output processor that has been assigned to an I/O pool. For a multi-system environment, this is one or more switchable expansion units (towers) properly configured on the HSL loop also containing the systems in the recovery domain. The switchable tower can also be used in an LPAR environment. For more planning information about switchable hardware and independent disk pools, see Plan for independent disk pools.