oracle rac的网卡必须要支持多播
If multicast based communication is not enabled as required either on the nodes of the cluster or on the network switches used for the private interconnect, the root.sh, which is called as part of a fresh installation of Oracle Grid Infrastructure 11.2.0.2, or the rootupgrade.sh (called as part of an upgrade to Oracle Grid Infrastructure 11.2.0.2) will only succeed on the first node of the cluster, but will fail on subsequent nodes with the symptoms shown below:
CRS-4402: The CSS daemon was started in exclusive mode but found an active CSS daemon on node
An active cluster was found during exclusive startup, restarting to join the cluster
Failed to start Oracle Clusterware stack
Failed to start Cluster Synchorinisation Service in clustered mode at /u01/app/crs/11.2.0.2/crs/install/crsconfig_lib.pm line 1016.
/u01/app/crs/11.2.0.2/perl/bin/perl -I/u01/app/crs/11.2.0.2/perl/lib -I/u01/app/crs/11.2.0.2/crs/install /u01/app/crs/11.2.0.2/crs/install/rootcrs.pl execution failed
检查方法：
1、ifconfig命令看到MULTICAST关键字，基本可以确定该网卡是支持多播的
2、使用官方工具mcasttest.pl(官方文档1212703.1)，下载工具包并解压后执行命令
perl mcasttest.pl -n <node1>,<node2>,<node_n...> -i <interface1>,<interface2><interface_n...>
例：perl mcasttest.pl -n ora11gdb1,ora11gdb2 -i eth1,eth2