Cabletron Systems FRM User Manual - page 126
9-2
Frame Relay Module 4. 0 User G uide, Rev 01
Each 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 transparent
mode (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 remote
connection over frame relay (via RFC1490) or X.25 (via QLLC) between two SNA
devices, one attached to a LAN and the other attached to either another LAN or a
frame relay-compliant SNA/APPN device. Each SNA host and terminal accessing the
FRM—via SDLC, LLC2, frame relay, or X.25—will appear to a local LLC2-attached
terminal 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):
●
Connection between a LAN-attached host/workstation and SNA devices, via
SDLC-to-LLC2 and LLC2-to-SDLC conversion, over a frame relay or X.25
network (example 1), or frame relay PVC (example 4).
●
Connection between LAN-attached workstations, over a frame relay or X.25
network (example 2), or a frame relay PVC (example 3).
●
Connection between workstations attached to different LANs on the same FRM.
Protocol conversion is accomplished by terminating an SDLC connection in the FRM
and 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 Examples
Required Configuration
To run SNA in an FRM, make sure the following are correctly configured:
1
PUs
SDLC
Host
PUs
Host
PUs
Frame Relay PVC
Router
Host
FRM 1
FRM 2
FRM 1
FRM 2
FRM
2
3
4
PUs
SDLC
FRM
FEP
Host