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# A Network Configuration Considerations

This appendix describes the network considerations for the Microsoft Windows software.

This appendix covers the following topics:

- Registering Host Names and IP Addresses

- Validating Proper Name Resolution in the Cluster

- Changing IP Addresses of Cluster Nodes

- Troubleshooting Problems with Improper Name Resolution

## A.1 Registering Host Names and IP Addresses

Each IP address and its corresponding host name must be registered in either the Hosts file (in the `system32\drivers\etc\` directory under the system directory) on each cluster node or in DNS regardless of whether or not WINS is used. You must register all of the following addresses:

- Cluster node addresses

- Cluster alias address

- Virtual server addresses

- Oracle Fail Safe Manager client systems

If you make changes in any of the name registries (DNS server or Host file), then use the following command to purge the local cache and make the changes effective:

    nbtstat -R

## A.2 Validating Proper Name Resolution in the Cluster

This section describes how to ping all systems to validate that you have properly registered the IP addresses and host names. The procedures described in this section ensure that the same IP address is echoed when you ping a host name from the host itself and from any other systems.

Suppose there is a cluster of two systems and a client system. The host name of the systems and the cluster alias are shown in the following table:

System | Host Name
--- | ---
Cluster system 1 | ClusterHost1
Cluster system 2 | ClusterHost2
Cluster alias | ClusterAlias
Client system | ClientHost

On each system, Cluster system 1, Cluster system 2, and Client system ping all four host names. For example, on Cluster system 1:

    ping ClusterHost1

    ping ClusterHost2

    ping ClusterAlias

    ping ClientHost

For each host name that you ping, the ping test must echo the same IP address. For example, if ClusterHost1 is registered to map to IP address 192.1.99.202, then pinging ClusterHost1 on Cluster system 1, Cluster system 2, and Client system must echo 192.1.99.202.

If all ping tests are successful, then your network is configured correctly.

If any ping tests do not return the proper IP address, then see Section A.4.

## A.3 Changing IP Addresses of Cluster Nodes

A Microsoft Windows cluster system is typically composed of two nodes and two networks: a public network, which is used by clients of the cluster, and a private network called the cluster interconnect, which is used internally by the cluster hardware and software to monitor the state of the two nodes during their operation.

Thus, each node has at least two IP addresses, one on the public network and one on the private network (for example, 192.168.10.1 could be the IP address on the public network and 10.10.0.1 could be the IP address on the private network).

These addresses are specified in the Microsoft Cluster Server software.

The following steps describe how to change the IP addresses of cluster nodes in a Microsoft Windows cluster. The steps assume that there are two cluster nodes: Node A and Node B. The following steps are performed on Node A unless otherwise noted.

1. Open Oracle Fail Safe Manager and take all of the groups offline except the Cluster Group. (In the tree view, right-click a group, then select Take Offline. Repeat until all groups except the Cluster Group have been taken offline.)

2. Close Oracle Fail Safe Manager.

3. Open MSCS Cluster Administrator and check that all of the groups are offline except the Cluster Group. Then follow these steps:

   1. In the tree view, select the Resources folder.

   2. Right-click Oracle Services for MSCS and select Take Offline.

   3. Right-click a group and select Move Group. Repeat until all groups are moved to Node B.

4. Change the Cluster IP address (for Node A) in MSCS Cluster Administrator, as follows.

   1. Select the Resources folder.

   2. Right-click Cluster IP Address.

   3. Select Properties.

   4. Change the IP Address.

   5. Click OK.

5. For each group, change its IP address in MSCS Cluster Administrator, as follows:

   1. Select the Resources folder.

   2. Right-click the Network Name IP address for a group and select Properties.

   3. Change the network Name on the General tab and change the IP address Name on the Parameters tab.

   4. Click Apply.

   5. Repeat steps b through d for all of the groups.

6. Change the IP Address of the network adapter on Node A. (For instructions, see Microsoft Article ID: Q230356 - Changing the IP Address of Network Adapters in Cluster Server, available on the Microsoft Corporation Web site.)

7. Restart Node A.

8. After Node A restarts, open MSCS Cluster Administrator.

9. Right-click a group and select Move Group. Repeat until all groups are moved to Node A.

10. Change the IP Address of the network adapter on Node B.

11. Restart Node B.

12. After Node B restarts, update the host file on both Node A and Node B (located in `winnt/system32/drivers/etc/host`).

13. Update the DNS Server if necessary.

14. Open MSCS Cluster Administrator and ensure that the Cluster Group and all resources are online.

15. Open Oracle Fail Safe Manager and then perform the following steps:

    1. Ensure that all resources are online.

    2. Select the cluster from the tree view, and on the Troubleshooting menu, select Verify Cluster. Ensure that no warnings are returned due to a problem with host name to IP address resolution.

    3. Select a group from the tree view, and on the Troubleshooting menu, select Verify Group. This will report a number of errors in Oracle Net configuration files and Microsoft Windows services and will ask if you want the errors to be fixed. Accept all fixes and rerun the Verify Group operation until no more fixes are suggested and no warnings are produced.

    4. Repeat step 15c for each group on the cluster.

    5. Test manual failover of each group on both nodes and then test connectivity from clients. (To test manual failover of a group, right-click the group in the Oracle Fail Safe Manager tree view, then select Move Group.)

## A.4 Troubleshooting Problems with Improper Name Resolution

If the ping test in Section A.2 does not return the correct addresses, then one of the following is probably causing the discrepancy:

- You have incorrectly registered the IP address, or the host name, or both in the Host file or with the DNS server.

  If you suspect this is the problem, then reexamine Section A.1 to ensure that you have registered the addresses correctly, or contact your network administrator to verify your IP addresses and host names.

- You have multiple network interface cards.

  On a system with multiple network interface cards, multiple IP addresses are assigned to the host name. For example, Cluster system 1 has two network interface cards. Each card is assigned an IP address on a different network or subnet, as follows:

  Network | IP Address
  --- | ---
  Net1 | 192.1.22.101
  Net2 | 192.1.99.202

  On system Cluster system 1, host name ClusterHost1 maps to both IP addresses, although the ping program echoes only one IP address. If the ping program does not echo the same IP address that is echoed on other systems, then it could mean that there is an ordering problem with the IP addresses for the host name.

  Refer to the Microsoft Windows documentation for information about correcting an ordering problem.