There are two configuration requirements for participation in the campus IPX internetwork: standard IPX network numbers and Ethernet_II frametypes on NetWare servers and clients.

IPX Network numbers:
Your server is configured with internal and "external" IPX network numbers. Throughout the campus IPX network numbers two rules must be followed regarding IPX networks:

1. Different networks must be assigned different numbers.

2. The servers and routers on the same network must assign it the same number.

In order to guarantee that these rules are followed, DCNS developed an IPX network numbering scheme based on the IP address of the NetWare servers and the address of subnetworks:

A NetWare server's internal IPX network should be the hexadecimal conversion of its entire IP address. Convert each portion of the IP address (in dotted decimal notation) to hexadecimal. Concatenate the portions. E.g., convert each portion of the server's IP address (equal to 128.32.152.38): 128 decimal is 80 hexadecimal, 32 decimal is 20 hexadecimal, 152 is 98, 38 is 26. Concatenate the four hexadecimal numbers: 80209826. This is the server's internal IPX network number. This guarantees that all NetWare servers will use a unique internal IPX network number (Rule No. 1.)

Similarly convert the subnet network address to obtain the external IPX network number. There are actually two conventions for this, the original assumed our standard subnet mask (255.255.255.0) and a more recent convention accounts for variable length subnet masks. For example, we used to assign subnets strictly by the third byte, i.e., 128.32.136.0/24. But now we might use a longer subnet mask and split the subnet into 2 or 4 or more subnets, i.e., two subnets: 128.32.136.0/25 and 128.32.136.128/25. The /X denotes the number of bits in the subnet mask, 25 = 8 + 8 + 8 + 1, or 255.255.255.128.

In the case of a /24 subnet mask the external IPX network number is the hexadecimal conversion of the first three bytes of the IP address. E.g., 128.32.152 would be 802098. In this way, all NetWare servers will agree on the IPX network number for subnet 128.32.152 (Rule No. 2). It also guarantees that no external network numbers will collide with internal network numbers.

In the case of /25 or /26 (or other longer subnet masks) the IPX external number is the hexadecimal conversion of all four bytes of the IP address of the network. E.g., 128.32.136.0/25 converts to 80208800 while 128.32.136.128/25 converts to 80208880. Thus the two subnets created out of the space previously used by one, still have unique IPX network numbers. The IP address of the network is the same as an "all zero's" broadcast address and is usually one less than the router or default gateway address.

Ethernet Frametypes:
NetWare servers version 3.x and greater support four separate Ethernet framing schemes (version 2.x servers support two.) Two devices framing IPX packets in different Ethernet frame types will not be able to communicate. In order to minimize the number of Ethernet frametypes that servers must load, and to maintain compatibility with other protocols, DCNS requires standardizing on the Ethernet_II frame for IPX in both your NetWare server and its clients.

For more information see The IPX networking FAQ.