Cabletron Systems Netlink FRX4000 User Manual - page 144
9-2
FRX4000/FRX6000 4.0 User Guide, 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 FRX4000/6000 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 FRX4000/6000—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 FRX4000/6000 includes the following scenarios, some of which
are diagrammed in
Figure 9-1
(on page 9-3):
●
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
FRX4000/6000.
Support of end-to-end LLC2 connections in an FRX4000 requires that the
full LLC2 protocol (not LLC2-R) be configured and loaded in the RLP file,
as described in
Chapter 5
. (LLC2-R does support conversion.)
Protocol conversion is accomplished by terminating an SDLC connection in the
FRX4000/6000 and establishing an LLC2 connection to the SNA host.
The following figure shows some examples of SDLC and LLC2 configurations. Note
that the LANs shown are all Token Ring. The same examples can be presented with
Ethernet LANs.