Cluster in private network

In the above example, the client host and cluster hosts are in same network. Also, the remote executable programs which execute on the cluster node hosts are activated directly for the client host. In the case in which the cluster and client host are in different networks, programs can communicate to the client host from a cluster node host.

But, as the number of node hosts increases, so do the clusters connected to the local-address network. In this situation, only the server host has a global IP address; the node hosts have local IP addresses. For OmniRPC, the cluster node host must communicate with the client host, but in this situation the cluster node host cannot communicate directly with the client host outside the cluster's network.

In this situation, there are 2 ways to use the cluster.

1. Set NAT to communicate with outside networks from the cluster node hosts. Programs can connect to anonymous ports on the client node from each cluster node. For the setting of NAT, please refer to NAT documents.

2. By using the agent function of multiplex communication, the agent relays communications between remote executable programs, which are executed on the cluster node host and client host.

We show an example hostile.xml which is based on the second way to use the cluster.

<?xml version="1.0" ?>
<OmniRpcConfig>
   <Host name="hpc-serv.hpcc.jp" arch="i386" os="linux">
   <Agent invoker="rsh" mxio="on" />
   <JobScheduler type="rr" maxjob="4" />
   </Host>
</OmniRpcConfig>

You should set the mxio attribute on the agent element with "on." In this case, because we assume that the cluster server host and client host are in same network, we use "rsh." If you want to invoke the agent with SSH, set "ssh". If you want to do this with the Globus gate keeper, use "globus."

Using this option, the relationship is shown in the figure below.

The agent relays communications between every rex which is executed on the remote node host and the client.