| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1480.1 | | 56821::STEFANI | Have the # for the Mars Observer? | Thu Oct 20 1994 14:20 | 22 |
| >>One of our customers noted that we had a partnumber chang from DEFEA-UB
>>to DEFEA-UA. Now he realy wants to know what the difference is between
>>both.
DEFEA-UB is FCC Class A certified and DEFEA-UA is FCC Class B
certified. Confusing, isn't it? :-)
>>Second question: does UTP-PMD and STP-PMD use the same MLT3 coding ?
>>I'm confused about this because in this conference I found that they
>>both use MLT3 but my customer who I realy respect for his technical
>>knowledge in this field told me the inverse. According to him:
>> UTP-PMD uses MLT3 and
>> STP-PMD uses NRZI.
>>Who is right ?
If the controller supports the ANSI TP-PMD standard, then it uses the
MLT3 encoding. I don't believe anyone makes a distinction between a
UTP or STP PMD. The NRZ encoding was the older Crescendo CDDI
equipment, which we've never supported in our hub products. Is there a
particular Digital networking product that's in question?
- Larry
|
| 1480.2 | | BIS5::RUTTENS | | Fri Oct 21 1994 05:19 | 17 |
| Many thanks larry.
Concerning my second question.
The real problem is that we want to connect a FDDI-Turbochannel 700-c
controller to a DECconcentrator 900MX. AS you know the 700-c has a
BNC and a STP (DB-9) output. So, we want to connect the STP output of
the 700-c to the UTP of the DC900MX.
My concern with this appart from the impedance difference (wich can be
solfed with a balum) is the encoding of both PMD's. If their is a
difference in encoding we can't get arround with or without balum.
If their is no differnce in the encoding can you tell me what cable we
have to use to make this work.
Rgds.....P.
|
| 1480.3 | | 56821::MELARAGNI | | Fri Oct 21 1994 08:47 | 13 |
| You cannot connect a DEFZA-Cx to a TP-PMD card and expect it to work.
Why?
1) The DEFZA uses simple NRZI encoding, 900MX uses MLT-3
2) The DEFZA uses a coax cable that supports bidirectional data
flow, the 900MX does not (uses a duplex scheme)
3) DEFZA does not use scrambled data, 900MX does
4) Voltage levels are different and cannot be fixed w/ a simple
balun
We do not support coax FDDI on any new products, only TP-PMD.
bill
|
| 1480.4 | slight modification to .3 | 56821::MELARAGNI | | Fri Oct 21 1994 09:08 | 5 |
| ... i didn't read .2 carefully enough. The proposal was to connect the
STP port of the DEFZA to a TP-PMD port. That means item 2) can be
ignored. The other three are still correct.
bill
|
| 1480.5 | | BIS5::RUTTENS | | Mon Oct 24 1994 04:25 | 3 |
| thanks Bill.
|