Network Links User Guide

6 Using multipleEthernet driver units

Ethernet networks carry data using one of a number of different network protocols in their data packets. The 'frametype' header of each packet indicates which protocol the data uses.

Aleph One's Network Links software allows the PC Card to share a singleEthernet interface in the computer with RISC OS networking software. Itdoes this by directing packets to the relevant processor according tothe frame type. So long as different network protocols are being used bythe two systems this is straightforward; if the same protocol isrequired by both systems then more setup is required.

To allow the same protocol to be used twice a special technique knownas 'multiple driver units' or 'virtual Ethernet interfaces' is used. In thiscase the Ethernet driver software makes the Ethernet interface appear tobe two separate units, as if there were actually two Ethernet interfacesfitted to the computer.

Only some manufacturer's Ethernet drivers can do this, so you must havethe appropriate kind of card (see below). Of course, you could also havemultiple units by actually installing multiple/virtual Ethernet cards inone machine; a similar principle would apply.

6.1 - How to decidewhether multiple driver units are required
6.2 - Setting upmultiple units
6.3 - Setting up the!PC application to use the correct interface unit
6.4 - Testing yourmultiple/virtual driver setup