The information in the following sections applies strictly only to TCP/IP. However a very similar facility to the [tcpip_servers] section below is also implemented for IPX/SPX. Therefore it is worth reading this section for IPX/SPX networking as well. The IPX/SPX notes will explain the differences.
Remember, that except for multiple resilience configurations, you don't usually need to use server numbers at all with TCP/IP. You can use the -server_name command tail and real TCP/IP names.
With DP4 TCP/IP networking the DP4 TCP/IP requester will generate a name for the server it tries to contact based on the server number as follows:
| Server Number | Generated name | Comments |
|---|---|---|
| 0 | dp4server | This number must not be used in a multiple resilience configuration |
| 1-9 | dp4server01-dpserver09 | A leading zero is added to the number for servers 1 to 9 only, for compatibility with older releases. |
| 10-99 | dp4server10-dp4server99 | |
| 100-65535 | dp4server100-dp4server65535 | These numbers must not be used in a multiple resilience configurations. They are intended to be used in large networks where machines have a preallocated number that is available in the environment. Numbers in this range were not supported prior to release 4.520. |
Except on Windows platforms, the names used for servers must be resolvable by TCP/IP itself. You can either add entries to the hosts file, where this is in use, or you can use a name server (DNS) to add CNAME records for the names you need, which point to the real server names, or you can use DHCP and Dynamic DNS or, on Windows only, DHCP + WINS. DNS and DHCP make it much easier to manage a network, and you should use them if possible.
If you are using a hosts file it should contain entries of the
form
192.168.100.1 ntworkstation dp4server09
This entry indicates that DP4 server 9 is running on a machine identified as ntworkstation having the IP-address 192.168.100.1.
If absolutely necessary you can specify IP addresses for servers by specifying -address options on the command line for the tcp requester. For server number 0 (normally only used in simple client-server and local resiliency configurations), specify -address a.b.c.d . For other server numbers specify -address_n a.b.c.d , where n is the same as for the corresponding dp4serverN name. You are strongly urged not to use this method. It did not work properly in some earlier versions of DP4 networking.
On Windows (all versions) you can add a special section to the DP4 configuration file which maps these names to the real names that TCP/IP uses to reach the servers. You cannot use IP addresses in these entries. The syntax of this as follows:
[tcpip_servers]When looking for server number NN, tcpw first constructs the dp4serverNN name in the normal way, and then looks for a translation of this name by looking for a corresponding entry in the [tcpip_servers] section of the DP4 configuration file.
When multiple resilience is in use it is important that you number your servers consistently. For example, it is perfectly possible to accidentally configure different clients so that they use the same server number for different DP4 servers (for example one has dp4server01=fred, and the other has dp4server01=jim), or to use different server numbers for the same DP4 server. This may potentially lead to unforeseen problems, because the multiple resilience software passes the "online" status of the various servers around the network based on DP4 server numbers. (See Network Status Table with Multiple Resilience for details).