Beatrice,
As Yatin suggested, if you keep your SNA traffic in one VLAN it should work fine.
I would add, see if you can transition the application to TCP/IP somehow. I have had a lot of customers who have done this with their AS400's over the years, with much success. It keeps things simpler on the networking side.
If you must run SNA across VLANs, then you're probably looking at additional Cisco IOS routers running Data Link Switching (DLSw) or Data Link Switching Plus (DLSw+) to push the SNA traffic through IP tunnels, so it can bridge via the IP routed network. I have had a few customers do this because they couldn't keep all the SNA traffic in one VLAN, and did not want to bridge their VLANs. (They are looking into migrating the applications to IP, though.)
You could bridge SNA traffic between VLANs; but bridging non-routed traffic could end up passing a lot of undesirable traffic between VLANs. I suppose you could filter the bridged traffic so that only SNA traffic that gets bridged; but this would require detailed knowledge about SNA. I have done this for DEC LAT, which is also a non-routable protocol, and for DECNet; maybe there's a way to do it with SNA too. I just never had the chance to figure out how: every time I've run into SNA, it's been handled as outlined above (single VLAN, DLSW/DLSW+, or migration to TCP/IP).
Hope this helps.
