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Dynamic IP Addressing for LSF Hosts

This chapter describes how to use dynamic IP addressing with an LSF cluster.

Contents

About Dynamic Host Configuration Protocol (DHCP)

DHCP (Dynamic Host Configuration Protocol) enables individual computers on an IP network to extract their configurations from particular machines (DHCP servers) that have no exact information about the individual computers until they request the information. This reduces the work necessary to administer a large IP network. The most significant piece of information distributed in this manner is the IP address.

How LSF works with dynamic IP addressing

LSF hosts running Windows can be configured as DHCP clients, which means their IP address is dynamic. Users who dial in or connect from a remote location might be assigned a different IP address with each connection.

The DHCP server issues an IP address to the LSF host, but LSF gets the IP address from DNS (Domain Name System). A WINS (Windows Internet Naming Service) server synchronizes information between the DHCP and DNS servers.

The IP address should not be changed while there are active TCP/IP connections with the host, for example, while installing LSF or running LSF commands. Normally, the IP address is maintained until the host is restarted or until the network connection is broken.

If an LSF client host is assigned a new IP address, you should wait for WINS to update DNS before you use that host to run LSF.

LSF client hosts

LSF client hosts can be DHCP clients and can change their IP addresses anytime in a running cluster.

LSF server hosts

Installing dynamic hosts on Windows allows support for dynamic IP addressing for LSF server hosts using DHCP.

LSF server hosts can be DHCP clients and can change their IP addresses anytime in a running cluster. The master host also saves the slave host IP address.

Setup

To run LSF on hosts that are DHCP clients, take these steps.

  1. Make sure your system uses DHCP, DNS, and WINS. See Requirements.
  2. Configure a short cache timeout value on the WINS server. See Configuring WINS.
  3. Enable dynamic IP addressing for the LSF cluster. See Configuring dynamic IP addressing.

Requirements

To use DHCP with LSF, your system must include all of the following:

Configuring WINS

The Cache Timeout Value for the WINS Lookup of the DNS should be as short as possible (the 10-minute default may be acceptable, but this should not be increased).

When an LSF client host is assigned a new IP address, you should wait this long before you use the client host to run LSF. This prevents possible conflicts by allowing time for the DNS to be updated.

Configuring dynamic IP addressing

By default, dynamic IP addressing is not enabled. To enable dynamic IP addressing for the cluster:

  1. Configure the following parameter in lsf.conf: LSF_DHCP_ENV=Y
  2. Reconfigure the cluster:
  3. lsadmin reconfig
    badmin reconfig 
    
  4. LSF checks for any configuration errors. If no fatal errors are found, you are asked to confirm reconfiguration. If fatal errors are found, reconfiguration is aborted.

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