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Conference noted::decnis

Title: DEC Network Integration Server (DECNIS)
Notice:Please read note 1 to use this conference effectively
Moderator:MARVIN::WELCH
Created:Wed Sep 18 1991
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3660
Total number of notes:15082

3538.0. "Clock setting when using HS w622 card" by PATS::NETWORK () Wed Feb 12 1997 20:28

We have a problem using Hs W622 card at 6meg. When we loose one T1 out
of the 4, we loose the hole circuit.
The clock is setted to reflected.
The circuit provider is telling us to set the clock to 3dinverted ? Have
anyone used this option unknow to me ?
Have anyone used DigitalLink 3800 MUX with DECnis and Hs W622 card?

Thank you,
/lillemor
T.RTitleUserPersonal
Name
DateLines
3538.1Use reflected clocks at 6MMARVIN::HIGGINSONPeter Higginson DTN 830 6293, Reading UKThu Feb 13 1997 06:2739
I've no idea what 3dinverted is - if it's a reference to some encoding
(like HDB3) then thats between the 3800 and the lines and nothing to do
with the DECNIS.

If it works at 6M then the DECNIS end is probably ok.

In all cases, particularly when it fails, what does the DECNIS measure
the "actual speed" as and what are the error counters (ncl sho mod conn
lin * all).

Does it fail when any T1 is removed or only the first one (a customer did
have that problem in the 3800)?

===============================================================================

From my reply to your previous posting, discussing the clocks between
3800 and the DECNIS and the only use of inverted I've come accross:


In normal circumstances, with fixed speed clocks, it only matters
to find a stable part of the clock to trigger off. A common trick
is to use inverted clocks to sample one half bit late in order to
get a stable part of the data signal.

With variable speed clocks late sampling is a disaster because if
it works at 6M, it will be exactly wrong at 3M (because half a bit
is now a bit time).

Hence you must use short cable lengths and reflected clocks at 6M.

Apart from really making sure that it is a 622HS card - see if it
can measure the clock speed accurately don't trust the label - all
the other problems we have had have been down to Digital Link.

Were the T1 lines all ordered together? (clock and/or analogue/digital
mixtures have caused problems).

Peter
3538.2only problem at 4.5 megPATS::NETWORKThu Feb 13 1997 12:518
    The DECnis gets the right speed but the circuit is not passing data
    when we have lost one T1. We have no problem running with 3 T1s, 2 T1s and
    1 T1.
    You said that there were another case like this, what did you do to fix
    it ? Shorter cables ?
    Thank you,
    /lillemro
    
3538.3MARVIN::HIGGINSONPeter Higginson DTN 830 6293, Reading UKThu Feb 13 1997 16:2915
There is (or should be) no difference from the DECNIS point of view
between 3 T1's and 4 T1's with one down.

Hence this is a DL 3800 problem.

2nd hand from a customer went something like "The DL 3800 takes it's
clock from the 1st T1 and wasn't able to cope when other T1's had
clocks from different sources or the first T1 was lost"

(Anyone from the CSC remember any more about this??)

Is the actual speed in the cases "3 T1's" and "4 T1's with one down" the same?

Peter
3538.4PATS::NETWORKThu Feb 13 1997 20:012
    We had a problem when any of the 4 T1 was down. The circuit is fine at
    6meg,3meg, 1.5 meg, problem only at 4.5 meg.
3538.5MARVIN::HIGGINSONPeter Higginson DTN 830 6293, Reading UKThu Feb 13 1997 20:236
But an earlier reply says that 3 T1's is ok - that's 4.5M. I don't see
how the DECNIS can tell the difference - what does it think the speed is?

Peter

3538.6PATS::NETWORKFri Feb 14 1997 12:0510
The problem we have is that the decnis do not pass data over the circuit
when 1 T1 out of the 4 T1s is down. The DECnis show the actual speed 4.5
but are not passing data, and after a few minuts we lose adjacency.

We have no problem when we have lost 2 T1s out of 4, actual speed 3meg
and passing data fine, no problem when we have lost 3 T1s out of 4, actual
speed 1.5 meg and passing data.

/lillemor