6    Managing Networks in a Cluster

This chapter discusses the following topics:

See the Tru64 UNIX Network Administration: Connections and Network Administration: Services manuals for information about managing networks on single systems.

6.1    Providing Failover for Network Interfaces

The Redundant Array of Independent Network Adapters (NetRAIN) interface provides protection against certain kinds of network connectivity failures. NetRAIN integrates multiple network interfaces on the same LAN segment into a single virtual interface called a NetRAIN set. One network interface in the set is active while the others remain idle. If the active interface fails, one of the idle set members comes on line with the same IP address.

The Network Interface Failure Finder (NIFF) is an additional feature that monitors the status of its network interfaces and reports indications of network failures. You can use NIFF to generate events when network devices, including a composite NetRAIN device, fail. You can monitor these events and take appropriate actions when a failure occurs.

To configure NIFF in a cluster, you must enable the NIFF daemon, niffd, on each cluster member. For example, to enable startup of niffd and have NIFF monitor the tu network interface, log in to each cluster member (or use the -h to rcmgr) and enter the following commands: 

# rcmgr set NIFFD "YES"
# rcmgr set NIFFC_FLAGS "-a tu0"

For information about providing failover for applications that depend on network resources, see the TruCluster Server Cluster Highly Available Applications manual.

For more information about NIFF and NetRAIN, see the Tru64 UNIX Network Administration: Services and Network Administration: Connections manuals, niffd(8), niff(7), and nr(7). For more information on the rcmgr command, see rcmgr(8).

6.2    Running IP Routers

Cluster members can be IP routers, and you can configure more than one member as an IP router. However, the only supported way to do this requires that you use the TruCluster Server gated configuration. You can customize the gated configuration to run a specialized routing environment. For example, you can run a routing protocol such as Open Shortest Path First (OSPF).

To run a customized gated configuration on a cluster member, log on to that member and follow these steps:

  1. If gated is running, stop it with the following command: 

    # /sbin/init.d/gateway stop

  2. Enter the following command: 

    #  cluamgr -r start,nogated

  3. Modify gated.conf (or the name that you are using for the configuration file). Use the version of /etc/gated.conf.membern that was created by the cluamgr -r nogated,start command as the basis for edits to a customized gated configuration file. You will need to correctly merge the cluster alias information from the /etc/gated.conf.membern file into your customized configuration file.

  4. Start gated with the following command: 

    # /sbin/init.d/gateway start

The cluamgr -r start,nogated command does the following tasks:

The option to customize the gated configuration is provided solely to allow a knowledgeable system manager to modify the standard TruCluster Server version of gated.conf so that it adds support needed for that member's routing operations. After the modification, gated is run to allow the member to operate as a customized router.

For more information, see cluamgr(8)

Notes

The cluamgr option nogated is not a means to allow the use of routed.

Only gated is supported.

We strongly recommend that cluster members use routing only for cluster alias support, and that the job of general-purpose IP routing within the network be handled by general-purpose routers that are tuned for that function.

6.3    Configuring the Network

Typically, you configure the network when you install the Tru64 UNIX Version 5.1A software. If you later need to alter the network configuration, the following information might be useful. Use the sysman net_wizard command or the equivalent command, netconfig to configure the following:

You can run the nfsconfig command without any focus. In this case, the configurations that are performed are considered to be clusterwide, and all configurations are placed in the /etc/rc.config.common file.

If you specify a focus member, either on the command line or through the Sysman Menu, the configurations are performed for the specified member. All configurations are placed in the member-specific /etc/rc.config file.

The following configuration tasks require a focus member:

Starting and stopping network services also requires member focus.

The preceding tasks require focus on a specific member because they are member-specific functions. A restart or stop of network services clusterwide would be disruptive; therefore, these tasks are performed on one member at a time.

The following configuration tasks must be run clusterwide:

For information about configuring DHCP, see Section 7.1.