Network-Configuration Files

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Network-Configuration Files

This section identifies and explains the use of network-configuration files on TCP/IP and IPX/SPX networks.

TCP/IP Connectivity Files

When you configure the database server to use the TCP/IP network protocol, you use information from the network-configuration files hosts and services to prepare the sqlhosts information.

The network administrator maintains these files. When you add a host, or a software service such as a database server, you need to inform the network administrator so that person can make sure the information in these files is accurate.

The hosts file needs a single entry for each network-controller card that connects a computer running an IBM Informix client/server product on the network. Each line in the file contains the following information:

Internet address (or ethernet card IP address)
Host name
Host aliases (optional)

Although the length of the host name is not limited in the hosts file, Informix limits the host name to 256 characters. Table 7 includes a sample hosts file.

The services file contains an entry for each service available through TCP/IP. Each entry is a single line that contains the following information:

Service name
IBM Informix products use this name to determine the port number and protocol for making client/server connections. The service name can have up to 128 characters.
Port number and protocol
The port number is the computer port, and the protocol for TCP/IP is tcp.
Aliases (optional)

The service name and port number are arbitrary. However, they must be unique within the context of the file and must be identical on all computers that are running IBM Informix client/server products. The aliases field is optional. For example, a services file might include the following entry for a database server:

server2      1526/tcp

This entry makes server2 known as the service name for TCP port 1526. A database server can then use this port to service connection requests. Figure 12 includes a sample services file.

For information about the hosts and services files, refer to your operatingsystem documentation.

On UNIX, the hosts and services files are in the /etc directory. The files must be present on each computer that runs an IBM Informix client/server product, or on the NIS server if your network uses Network Information Service (NIS).

Warning:

On systems that use NIS, the /etc/hosts and /etc/services files are maintained on the NIS server. The /etc/hosts and /etc/services files that reside on your local computer might not be used and might not be up to date . To view the contents of the NIS files, enter the following commands on the command line:

ypcat hosts
ypcat services

Multiple TCP/IP Ports

To take advantage of multiple ethernet cards, take the following actions:

Make an entry in the services file for each port the database server will use, as in the following example:
```
soc1         21/tcp
soc2         22/tcp
```
All ports in use for a single IP address must be unique. Separate ethernet cards can utilize the same or different port numbers. You might want to use the same port number on each ethernet card because you are connecting to the same database server. (In this scenario, the service name is the same.)
Put one entry per ethernet card in the hosts file with a separate IP address, as in the following example:
```
192.147.104.19          svc8
192.147.104.20          svc81
```
In the ONCONFIG configuration file, enter DBSERVERNAME for one of the ethernet cards and DBSERVERALIASES for the other ethernet card. The following lines show sample entries in the ONCONFIG file:
```
DBSERVERNAME chicago1
DBSERVERALIASES chicago2
```
In the sqlhosts file, make one entry for each ethernet card. That is, make an entry for the DBSERVERNAME and another entry for the DBSERVERALIAS.
```
chicago1 onsoctcp svc8 soc1
chicago2 onsoctcp svc81 soc2
```

Once this configuration is in place, the application communicates through the ethernet card assigned to the dbservername that the INFORMIXSERVER environment variable provides.

IPX/SPX Connectivity Files

To configure the database server to use the IPX/SPX protocol on a UNIX network, you must purchase IPX/SPX software and install it on the database server computer. Your choice of IPX/SPX software depends on the operating system that you are using. For some operating systems, the IPX/SPX software is bundled with software products based on NetWare for UNIX or Portable NetWare. In addition, for each of the UNIX vendors that distributes IPX/SPX software, you might find a different set of configuration files.

For advice on how to set configuration files for these software products, consult the manuals that accompany your IPX/SPX software.