Ref: 03250402
Title: Configuring T1 Links with Avanti AccuPac 1.5 CSU/DSU
Date: 5/9/88

Copyright 3Com Corporation, 1991.  All rights reserved.

QUESTION:  We are bringing up a couple T1 links with an IB/3
using the Avanti AccuPac-1.5, which is a recommended 3Com CSU/
DSU.  We want to verify the configuration settings for channel
address and data rate.  What configurations have you used?  We
are going by the manual and believe everything is correct.

ANSWER:  We have seen only one problem with the AccuPac's.  There
is a plastic tag on a cable which runs above the top board in the
AccuPac which may be lodged into the backplane connector, thus
insulating some of the fingers from the backplane connector. This
should be checked if problems arise.  We have seen no other
problems, and we were able to set it up following the manual.  We
ran it at 1536 Kbps.  For this data rate, I believe it would be
set up with:

    S5: 10 = ON                 S2: 1,-2,-3,-4,-5,-9 = ON
                                S2: 6,-7,-8,-10 = OFF
    S3: = All OFF               S5: 2,-3,-5,-6,-7,-9,-10 = ON
                                S5: 1,-4,-8 = OFF
    S1: 1,-2,-3,-4,-5,-6,-9,-10 = OFF
    S1: 7,-8 = ON

These switch setting were for the AccuPac 1.5 ONLY.  An ISU
(Integral Service Unit) is required to interface the AccuPac 1.5
to the T1 span.  This device is described in an appendix to the
AccuPac 1.5 manual.  I haven't worked with the ISU, as a result,
our switch settings for S5 and S1 were different from those
above.  (We were unable to get a clock source from a TelCo line
as we weren't connected to one.)

If the switch settings above do not work, see the manual.  Differences
between these settings and those for back-to-back may be meaningful.
The following are the back-to-back settings we used to test Avanti's.

   Loopback Settings (AccuPac-1.5's back-to-back):

   S1:      1-3,6,8,9 up            1-6,8,9 up
            4,5,7,10 down           7,10 down

   S2:      1-5,9 up
            6-8,10 down             SAME

   S3:      All down                SAME

   S5:      1,3,7-9 up              1,3,7,8 up
            2,4-6,10 down           2,4-6,9,10 down

