我想用 nodetool 我们的Cassandra产品数据库。但是，当我试图从本地机器针对cassandra生产集群启动nodetool时，我就遇到了一个异常。

S:\Apache Cassandra\apache-cassandra-1.2.3\bin>nodetool -h pdb.vip.phx.host.com compactionstats
Starting NodeTool
Error connecting to remote JMX agent!
java.io.IOException: Failed to retrieve RMIServer stub: javax.naming.CommunicationException [Root exception is java.rmi.ConnectIOException: error duri
ng JRMP connection establishment; nested exception is:
        java.net.SocketTimeoutException: Read timed out]
        at javax.management.remote.rmi.RMIConnector.connect(Unknown Source)
        at javax.management.remote.JMXConnectorFactory.connect(Unknown Source)
        at org.apache.cassandra.tools.NodeProbe.connect(NodeProbe.java:145)
        at org.apache.cassandra.tools.NodeProbe.<init>(NodeProbe.java:115)
        at org.apache.cassandra.tools.NodeCmd.main(NodeCmd.java:966)
Caused by: javax.naming.CommunicationException [Root exception is java.rmi.ConnectIOException: error during JRMP connection establishment; nested exce
ption is:
        java.net.SocketTimeoutException: Read timed out]
        at com.sun.jndi.rmi.registry.RegistryContext.lookup(Unknown Source)
        at com.sun.jndi.toolkit.url.GenericURLContext.lookup(Unknown Source)
        at javax.naming.InitialContext.lookup(Unknown Source)
        at javax.management.remote.rmi.RMIConnector.findRMIServerJNDI(Unknown Source)
        at javax.management.remote.rmi.RMIConnector.findRMIServer(Unknown Source)
        ... 5 more
Caused by: java.rmi.ConnectIOException: error during JRMP connection establishment; nested exception is:
        java.net.SocketTimeoutException: Read timed out
        at sun.rmi.transport.tcp.TCPChannel.createConnection(Unknown Source)
        at sun.rmi.transport.tcp.TCPChannel.newConnection(Unknown Source)
        at sun.rmi.server.UnicastRef.newCall(Unknown Source)
        at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
        ... 10 more
Caused by: java.net.SocketTimeoutException: Read timed out
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.read(Unknown Source)
        at java.io.BufferedInputStream.fill(Unknown Source)
        at java.io.BufferedInputStream.read(Unknown Source)
        at java.io.DataInputStream.readByte(Unknown Source)
        ... 14 more

谁能给我一些想法，为什么我会看到这个例外？任何帮助都将不胜感激。