First, consider really whether the SNA step is necessary any longer. tn3270 directly to the host is not the resource pig it used to be.
Second, there's two stages here: desktop to Linux (which needs only IP) and Linux to VTAM, which needs to be layer 2 clean (eg TYPE ETHERNET guest LAN). VLANs are a refinement to the plan. Crude picture: Client --IP-> Linux - SNA --> VTAM The first hop (client to Linux) can be a direct OSA connection or delivered via a virtual NIC connected to a VSWITCH connected to a VLAN-aware physical switch. The second hop is a different network segment (could be a different VSWITCH or layer 2 GLAN, or a different VLAN number on the same VSWITCH - -I'd suggest the first option). You don't care about the MAC address on the first hop. You care deeply about the MAC address of the second hop. I'd suggest: Set up the Linux guest and set the IP address on eth0. Define a second VSWITCH or layer 2 GLAN without giving it access to an OSA. Define and couple a second virtual nic on Linux to the second GLAN/VSWITCH. Make sure it has a fixed MAC address on the NICDEF in the directory entry for the Linux guest. Define and couple a second virtual NIC on VTAM to the second GLAN/VSWITCH. Make sure it has a fixed MAC addres in the NICDEF directory entry for VTAM (must be different than the other adapter above) Configure second adapter on Linux in the SNA software. Configure VTAM XCA and other members for the second adapter. Activate VTAM node Activate adapter in Linux At that point, the two SNA implementation should show connected and available. Once that's done and working, THEN configure the tn3270 server on Linux and allow it to start passing sessions to the SNA stack. > The solution I am thinking of now is to use real hardware to route my SNA > traffic back and > forth between VTAM and the z/LINUX SNA server on real OSA ports. > Is that right? Or have I missed something? Unnecessary. See above. Second repeat: seriously consider eliminating the front end and just run IP all the way into the other system, or switching to using the connection exit in the VM Telnet server to DIAL VTAM and go directly to SNA-land from there. This SNA server stuff is just way more complicated and costly than you need to support simple telnet functions.
