11.2.0.2 HAIP

早期的RAC，可能会出现因为private IP所用的网卡有问题，导致节点脱离集群，或者因为受网卡带宽的限制，影响集群的性能。11.2.0.2版本开始，最多可支持4个冗余的private IP。防止单点故障的同时，也同时进行网络传输的负载均衡。

You can define multiple interfaces for Redundant Interconnect Usage by classifying the interfaces as private either during installation or after installation using the oifcfg setif command. When you do, Oracle Clusterware creates from one to four (depending on the number of interfaces you define) highly available IP (HAIP) addresses, which Oracle Database and Oracle ASM instances use to ensure highly available and load balanced communications. The Oracle software (including Oracle RAC, Oracle ASM, and Oracle ACFS, all 11g release 2 (11.2.0.2), or later), by default, uses these HAIP addresses for all of its traffic, allowing for load balancing across the provided set of cluster interconnect interfaces. If one of the defined cluster interconnect interfaces fails or becomes non-communicative, then Oracle Clusterware transparently moves the corresponding HAIP address to one of the remaining functional interfaces.