If more than one network manager program is being run in a network, the various network managers on the servers can (and must for NetBIOS and for multiple resilience configurations) be given numbers to distinguish them. These numbers are allocated in the range 0 to 9999 (or 65535 for TCP/IP only).
In Multiple Resilience configurations the number should be between 1 and 99. Server number 0 has special significance to the multiple resilience software and must be avoided if multiple resilience is in use.
With NetBIOS networking the server number is used to construct a name such as DP4_NETBIOS_000, and clients are able to find the appropriate server automatically.
For other network protocols some form of address mapping is usually required, as described in Mapping of Server Numbers to Network Addresses.
The information in the following section applies strictly only to TCP/IP. However a very similar facility to the [tcpip_servers] section described there 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.
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]
dp4server=servername
dp4server01=servername01
..
..
dp4server09=servername09
dp4server10=servername10
..
..
dp4server99=servername99
dp4server100=servername100
..
dp4server65535=servername65535
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. 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.