If you are moving your PCs from token-ring to Ethernet, as some of us at MC are doing, you may not know that each network handles LAN addresses slightly differently. Both use 12 byte addresses, but they are transmitted in a different bit order. This affects how Client Access is configured; sometimes, the LAN address will need to be reversed to compensate for the differences. Client Access/400 for DOS Setup V3R1 (SC41-3556, CD-ROM QBKAK000), Appendix G, "Ethernet Address Considerations," has more information about when the address needs to be reversed and how to reverse them. Here's an overview.

Anytime you use Ethernet on the PC, the AS/400's address will need to be reversed when configuring Client Access. There are other circumstances in which the AS/400 or even the PC address will need to be reversed. You can either check the manual for the specifics or you can do as I do and reverse addresses one by one anytime you have a problem with a PC-to-AS/400 connection and can't find another problem. With the utility described below, it is much easier than trying to remember every rule.

The manual also lists a procedure that can be used to perform the reversal. A much simpler way is to get the DOS program REVERSE.EXE from the Client Access IWSTOOLs. Run program IWSTOOL in the QIWSTOOL shared folder and you will be prompted with a list of utilities and source code for Client Access. Select the one labeled "EXT2EPAC Token-Ring to Ethernet Address Conversion." Supply the destination path when prompted, and it will be extracted for you. The text file that is extracted with it can be deleted.

REVERSE.EXE can be run by supplying the address to be converted as a parameter. If no parameter is supplied, you will be prompted for one.

- Martin Pluth