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From: comtst!mdv@uunet.uu.net (Mike Verstegen)
Newsgroups: comp.dcom.telecom
Subject: Re: References/Fixes Needed For "Slippage" on Dialins
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Date: 4 Oct 90 15:53:31 GMT
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X-Telecom-Digest: Volume 10, Issue 716, Message 3 of 12


decoste@iro.umontreal.ca (Ronald Decoste) writes:

>We are also experiencing transmission errors with are dialup lines
>since our new phone switch went into operation.  Things were so bad
>that we had to revert to direct lines from the CO until a solution is
>found.

>The switch (multiple Meridian SL1's) is connected to the DMS-100 by a
>fiber DS-3 link for aapprox. 350 trunks.

>Brian Kantor's article suggests that some jumpers must be set properly
>on some interface cards.  Does anyone know more about this ?  Which
>jumpers on what cards for the DMS and for the SL1 ?

I have experieced this problem when a T-1 has been loop timed at each
end of the circuit. In timing distribution, one end (the "better"
timing) must always be master and the other end loop (or "slave")
timed. By definition the telco will be the master timing source.

If your DS-3 is terminating into an external M13 multiplexer, check
the timing connection between the M13 and the T-1 terminations on the
SL-1. The telco fiber DS-3 should time the M13 mux and the M13 will in
turn provide master timing via the T-1 to the SL-1 which should be
loop timed. If the the SL-1 is master timed (or the T-1 side of the
M13 is loop timed) you will see slippages that will cause data
transmissions problems.

If the DS-3 terminates directly into the SL-1, the integrated
interface probably has the equivalent options settings, either in
hardware or software.


Mike Verstegen          Domain Systems, Inc           Voice +1 407 686-7911
 ..!uunet!comtst!mdv    5840 Corporate Way #100       Fax   +1 407 478-2542
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