IPX/SPX basics

by Johannes Helmig [Published on 7 June 1998 / Last Updated on 7 June 1998]

Ethernet Network cards communicate using the MAC-addressing: the Ethernet address programmed into the network card by the manufacturer. You can view the Ethernet-address using the configuration program of the Network card (if it has one), like in this example for the 3C509:

If you have the TCP/IP protocol installed, you can use "WINIPCFG" to display the MAC-address (start it via the RUN-menu):

The first 6 digits of the Hexadecimal MAC-address indicate the manufacturer (large manufactures have several ID-codes), the last 6 digits are a unique number assigned by the manufacturer for each card.

This MAC/Ethernet-address is UNIQUE world-wide !

To understand now some of the requirements on setting up and configuring the IPX/SPX network protocol, it helps to understand the history of this protocol:

It was developed by NOVELL for for its PC-based fileserver product called "Netware". Multiple network boards can be installed in a Netware server, which is often done to improve network performance.

For EACH network-card with its attached network-cable, a NET-number is assigned on the Netware server (in addition, each Netware server requires an internal NET-number for itself).
These NET-numbers must be UNIQUE on the complete network.

The complete Network-address of a system using IPX/SPX-protocol is now the combination of NET-number and MAC-address (example for PC#1 on NET=2 using the 3C509 card listed above: 2.0060086DD3EE, for the PC#3 on NET=3 using the NE2000 listed above: 3.080000060560).

Since the original specification of the IPX/SPX-protocol by NOVELL, changes had to be made to the protocol, so that there are now MULTIPLE versions of the IPX/SPX-protocol, which differentiate by the FRAME-type:

- Ethernet 802.3
- Ethernet 802.2
- Ethernet_II

(When loading the NOVELL-drivers on a DOS-system, the FRAME-type MUST be defined in the NET.CFG file).

When using IPX/SPX-protocol on a Windows95 or Windows NT4 system to connect to a NOVELL-Netware or Windows NT server, it is very easy:

When installing a Network card, Windows95 installed a default set of Clients and protocols, which includes the IPX/SPX protocol.

If you are ONLY connecting to a NOVELL-Netware server, you can delete the not required components.

In this case, I started on my system, which is already configured with a Modem and TCP/IP for Internet connection. I am now loading the IPX/SPX Protocol.

Let's now look at the Configuration (=Properties) of the IPX/SPX protocol :

Tab: Advanced tem: Frame-Type: By default, the value is: AUTO.

When connecting to a Novell Netware server or Microsoft Windows NT server, leave the Frame-Type on AUTO: your System will sense on the network the appropriate Frame-Type and will use it them automatically.

But what, when you are using IPX/SPX to communicate between Windows95 systems in a PC-to-PC network and there is NO Novell or NT server on the network?

Since there is no server, the IPX/SPX-Frame-Type is not NOT defined on the network, so the default FRAME-Type setting of AUTO will NOT work! So, in such cases, you MUST configure yourself the Frame-type:

Select now a Frame-Type.

I usually select the Frame-Type: "Ethernet 802.3".

Please, also make sure, that on ALL systems, the IPX/SPX Network-address is the SAME.

See Also

The Author — Johannes Helmig

Dr.Johannes Helmig is working as Director, Technical Knowledge Management in the Belgium office of Gerber Technology where he is involved in Customer Service and internal training, with special interest in Networking.


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