oracle rac的网卡必须要支持多播，私有网卡不支持多播RAC搭建会有问题。

如果ifconfig命令看到MULTICAST关键字，基本可以确定该网卡是支持多播的

但是在极端情况下可能并不准确，这个时候就需要用到工具mcasttest.pl

在MOS:1212703.1中提供了检查多播的工具mcasttest.pl

加压好后运行命令就可以检查网卡是否支持多播

perl mcasttest.pl -n node1,node2  -i en0,en2

node1:节点名

en0：网卡名，有时会是eth0等

测试如下：

$ perl mcasttest.pl -n ntracd01,ntracd02 -i en0,en2
###########  Setup for node ntracd01  ##########
Checking node access 'ntracd01'
Checking node login 'ntracd01'
Checking/Creating Directory /tmp/mcasttest for binary on node 'ntracd01'
Distributing mcast2 binary to node 'ntracd01'
###########  Setup for node ntracd02  ##########
Checking node access 'ntracd02'
Checking node login 'ntracd02'
Checking/Creating Directory /tmp/mcasttest for binary on node 'ntracd02'
Distributing mcast2 binary to node 'ntracd02'
###########  testing Multicast on all nodes  ##########

Test for Multicast address 230.0.1.0

Sep 27 16:47:35 | Multicast Succeeded for en0 using address 230.0.1.0:42000
Sep 27 16:47:37 | Multicast Succeeded for en2 using address 230.0.1.0:42001

Test for Multicast address 224.0.0.251

Sep 27 16:47:38 | Multicast Succeeded for en0 using address 224.0.0.251:42002
Sep 27 16:47:39 | Multicast Succeeded for en2 using address 224.0.0.251:42003