Visara FEP-4600 Planning Guide - Manual (Page 14)

Chapter 1. FEP-4600 Overview
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Ethernet LLC-attached PU 2.1 Platforms
PU 2.1 platforms are supported downstream from the FEP-4600 on Ethernet networks
using LLC2 protocol. Upstream, PU2 traffic is routed through an XCA connection to
VTAM. Using this method up to 255 downstream PU 2.1 platforms can be supported
through a single XCA communication pipe. Up to 8 XCA communication pipes may be
defined for use with a single Ethernet interface (total of 2048 downstream PUs). Each
XCA Major Node definition uses one of the available 256 subchannels provided by the
ESCON interface.
For older units supporting the Luminex ESCON interface card, you could also define a
Channel Attached Major Node PU TYPE=2 in the VTAM definitions and UNIT=3174 in
the CNTLUNIT and IODEVICE macros. You must code XID=YES in the VTAM PU
definitions. A separate VTAM definition is required for each PU 2.1 node supported
directly through this gateway. Each Channel Attached Major Node requires one of the
available 256 subchannels provided by the ESCON interface.
DLSw can be supported by passing the LLC traffic to a router supporting LLC2/DLSw
conversion. The FEP-4600 also supports internal DLSw conversion (see Ethernet DLSw-
attached PU2.1 Platforms).
Ethernet LLC-attached PU 4 Platforms
PU 4 platforms are supported downstream from the FEP-4600 on Ethernet networks
using LLC2 protocol. Upstream, the definition is for a Channel Attached Major Node PU
TYPE=4 in the VTAM definitions and UNIT=SCTC in the CNTLUNIT and IODEVICE
macros. PU 4 connections can be either same-network or SNI. Multiple PU 4 connections
are supported through the same Ethernet interface. If support for DLSw is required, a
switch/router must be used to provide the LLC2/DLSw protocol conversion.
Ethernet DLSw-attached PU 2.0 Platforms
PU 2.0 platforms can be supported downstream from the FEP-4600 across IP networks
through the use of DLSw (Data Link Switching). The upstream connection is through the
XCA gateway interface. Typically you need a device on each end of the IP network to
convert LLC or SDLC traffic to DLSw traffic (SNA over IP). The FEP-4600 offers
internal DLSw support eliminating the need to pass LLC traffic over the local network.
When using internal DLSw, only IP traffic emerges over the Ethernet interface. External
routing of the IP traffic is still required by the FEP-4600 to move traffic beyond the local
network. The FEP-4600 requires another DLSw capable platform to reside at the remote
location to convert the DLSw traffic back to either LLC or SDLC. When using the Visara
1174 (3174 compatible) controller on the remote end, it is possible to let the 1174
perform the DLSw function directly, eliminating the need to have LLC or SDLC traffic
on the remote network. The Visara 1174 supports direct attachment of coax displays and
printers as well as TN3270 clients.