Ref: 22340009
Title: Configuring Black Box Protocol Converter for GS/X.25-(IP/XNS/OSI)
Date:   3/29/91

Copyright 3Com Corporation, 1991.  All rights reserved.

To set up a Black Box Protocol converter, V.35 (RS-232), for use with a
GS/X.25-(IP/XNS/OSI), follow these rules:

Set the shunt for the Black Box Protocol converter according to DTE/DCE
configurations.  If the RS-232 cable goes to a DTE configuration (no clocking
provided), the shunt on the RS-232 side must be set to DCE, and the V.35
shunt must be set as DTE and connect to a DCE source (providing clock).

The configuration would look like this:

         DTE <------>(RS-232)<--->DCE - DTE<--->(V.35)<------>DCE
    (no clocking)     cable  Protocol Converter  cable    (clocking)

                                    or

         DTE <------>(V.35)<--->DCE - DTE<--->(RS-232)<------>DCE
    (no clocking)    cable  Protocol Converter  cable    (clocking)


To set the protocol converter with RS-232 as DCE, set shunts like this:

     RS-232 = DCE XW1A & XW2A  V.35 = DTE XW3B & XW4B

To set the protocol converter with V.35 as DCE, set shunts like this:

     RS-232 = DTE XW1B & XW2B  V.35 = DCE XW3A & XW4A

Note:  When using a GS/X.25, the DTE/DCE Level 2 and Level 3 configurations
are not an issue.


For back-to-back setups, the modem eliminator cable must be on the
same cable interface that is providing the clock.  For example, if the GS
box that provides clock has the V.35 interface, the V.35 cable must be a
modem eliminator cable and the RS-232 cable must be straight-through to the
GS that does not provide clocking.

