This is possible to do with the SNA*ps Gateway and SNA*ps 5250.
This is a complex configuration mostly because the IBM 5494 is very
different from all previous IBM mid-range controllers. The IBM 5494 is an
APPC LEN device (similar to that of a SNA*ps Gateway). It attaches to the
AS/400 using special code included with OS/400 V2R2M0, which requires the
IBM 5494 to connect to the AS/400 as a Token Ring or SDLC based APPC
controller. (X.25 connection for SDLC is just fine). The Twinax devices
on the physical IBM 5494 have to be associated with some remote Workstation
controller on the AS/400 which manages the LU 4-7 sessions used by the
Twinax ports. The connection between the APPC connection and the Remote
Workstation controller is done by an AUTOCONFIGURED APPC parallel session
between the APPC 5494 connection and the Remote workstation controller. If
the IBM 5494 configuration is setup to support downstream PU 2.1 and
passthru to the AS/400, (such as a SNA*ps APPC gateway), then there is just
an APPC controller passing through the IBM 5494 to an APPC controller on
the AS/400. The IBM 5494 just provides the pipeline to the AS/400. This
is quite similar to how a SNA*ps Gateway in 3270 environments is a PU 2.0
downstream from IBM 3174 Cluster Controller.
Through all of this you need to know AS/400 Network IDs, Remote LUs, and
Local LUs for the SNA*ps APPC connection, and use known Mode descriptions.
That is all very basic information to a knowledgeable APPC system manager.
The most difficult to understand in the configuration of the SNA*ps Gateway
in this setup were the XIDs to be used. The Gateway XID in the SNA*ps
Gateway config can be anything, we used 050╩00000. BUT the XID for the
Partner (the IBM 5494 in this case) HAS to be 073╩00000, which is the
default value given the IBM 5494 if it is configured with downstream
support for PU 2.1 on Token Ring. Also, the Link address in the SNA*ps
config is the Token Ring address of the IBM 5494 controller which is placed
in the IBM 5494 when customization is done. The IBM 5494 does not care
about the Token Ring address of the SNA*ps Token Ring card (the address in
the Apple Token Ring Control Panel).
We would suggest that you carefully read the IBM 5494 documentation, and
get a copy of the current IBM RedBook on configuring 5494 to AS/400 - P/N
GG24-3828-00. We found it to be very helpful.