9-2 Frame Relay Module 4.0 User Guide, Rev 01Each SNA port can be configured to support SNA hosts (PU 2.1, 4.0 HPAD; NPAD)or terminals (PU 1.0, 2.0, 2.1 TPAD). A port can also be configured for a transparentmode (XPAD), which supports HDLC and any of its subset protocols, such as SDLC(IBM), LAPB (ISO), and BSC (bisync).LLC2 (Logical Link Control type 2) support in the FRM provides a local or remoteconnection over frame relay (via RFC1490) or X.25 (via QLLC) between two SNAdevices, one attached to a LAN and the other attached to either another LAN or aframe relay-compliant SNA/APPN device. Each SNA host and terminal accessing theFRM—via SDLC, LLC2, frame relay, or X.25—will appear to a local LLC2-attachedterminal or host as if it is directly connected to the local LAN.LLC2 support in the FRM includes the following scenarios, some of which are dia-grammed in Figure 9-1 (on page 9-2):l Connection between a LAN-attached host/workstation and SNA devices, viaSDLC-to-LLC2 and LLC2-to-SDLC conversion, over a frame relay or X.25network (example 1), or frame relay PVC (example 4).l Connection between LAN-attached workstations, over a frame relay or X.25network (example 2), or a frame relay PVC (example 3).l Connection between workstations attached to different LANs on the same FRM.Protocol conversion is accomplished by terminating an SDLC connection in the FRMand establishing an LLC2 connection to the SNA host.The following figure shows some examples of SDLC and LLC2 configurations.Figure 9-1 SDLC and LLC2 ExamplesRequired ConfigurationTo run SNA in an FRM, make sure the following are correctly configured:1PUsSDLC HostPUsHostPUs Frame Relay PVCRouterHostFRM 1 FRM 2FRM 1 FRM 2FRM234PUsSDLCFRM FEPHost
