IBM SG24-5131-00 manual Non-TCPIP Networks, Supported Non-TCP/IP Network Types

•SP Switch is a high-speed packet switching network, running on the RS/6000 SP system only. It runs bidirectionally up to 80 MBps, which adds up to 160 MBps of capacity per adapter. This is node-to-node communication and can be done in parallel between every pair of nodes inside an SP. The SP Switch network has to be defined as a private Network, and ARP must be enabled. This network is restricted to one adapter per node, thus, it has to be considered as a Single Point Of Failure. Therefore, it is strongly recommended to use AIX Error Notification to propagate a switch failure into a node failure when appropriate. As there is only one adapter per node, HACMP uses the ifconfig alias addresses for IPAT on the switch; so, a standby address is not necessary and, therefore, not used on the switch network. Hardware address swapping also is not supported on the SP Switch.

For IP Address Takeover (IPAT), in general, there are two adapters per cluster node and network recommended in order to eliminate single points of failure. The only exception to this rule is the SP Switch because of hardware limitations.

2.2.2 Non-TCPIP Networks

Non-TCP/IP networks in HACMP are used as an independent path for exchanging messages or heartbeats between cluster nodes. In case of an IP subsystem failure, HACMP can still differentiate between a network failure and a node failure when an independent path is available and functional. Below is a short description of the three currently available non-TCP/IP network types and their characteristics. Even though HACMP works without one, it is strongly recommended that you use at least one non-TCP/IP connection between the cluster nodes.

2.2.2.1 Supported Non-TCP/IP Network Types

Currently HACMP supports the following types of networks for non-TCP/IP heartbeat exchange between cluster nodes:

•Serial (RS232)

•Target-mode SCSI

•Target-mode SSA

All of them must be configured as Network Type: serial in the HACMP definitions.

14 IBM Certification Study Guide AIX HACMP